1544504_clarity

t h e m a g a z i n e o f C t • s p r i n g 2 0 0 9

clarityC T

introducing Discovery Ct750 hD A Moment in Timepage 42

ge takes a Leadership role in pediatric Ct imagingpage 55

CT Marches to the Front Lines of Trauma Imagingpage 30

taking Dose out of the pictureHow new GE HD technology dramatically cuts dose while boosting image definition.

GE Healthcare

imagination at work

FREE Procedure-Based Protocols Poster Inside!

372912_01_EP.indd 1 2/26/09 12:17:24 PM

2 A GE Healthcare CT publication • Spring 2009

C o n T E n T St a b l e o f

GE Healthcare News

Welcome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Calendar of events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

World’s First High Definition CT Scanner Sets new CT Image Clarity Standard . . . . . . . . . . . . . . . . . . . . . . .6

Simplifying Cardiovascular Ct . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Marketing Tools Help Customers Succeed . . . . . . . . . . . . . . . . . .8

new Toolkit Helps Increase Cardiac CTA Interpretation Skills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Introducing the LightSpeed VCT XTe,* Powered with HD Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Clinical Value

Setting new Standards in Computed Tomography . . . . . . . . 10

Low-dose Cardiac Cta: Five-month old with History of Apnea . . . . . . . . . . . . . . . . . . . . 16

Maximizing CT Perfusion Coverage for “Whole Territory” Stroke Assessment . . . . . . . . . . . . . . . . . . . . . 19

CT Simulation Advances Proton Beam Therapy by Helping overcome Challenges with Tumor Motion . . . . . . . . 24

a Promising new Tool for Myocardial Evaluation . . . . . . . . . . 27

CT Marches to the Front Lines of Trauma Imaging . . . . . . . . 30

Compact, Multi-detector CT Answers the Imaging Challenges for Japan’s Most Modern Hospitals . . . . . . . . . . . 34

low-dose Aorta, Iliac and Femoral Angiography with Prospective ECG-gated CT . . . . . . . . . . . . . . . . . . . . . . . . . . 37

GE Healthcare News: Introducing the LightSpeed VCT XTe,* Powered with HD Technologies page 9

© 2009 General Electric Company, doing business as GE Healthcare. All rights reserved. The copyright, trademarks, trade names and other intellectual property rights subsisting in or used in connection with and related to this publication are, the property of GE Healthcare unless otherwise specified. Reproduction in any form is forbidden without prior written permission from GE Healthcare.

LIMITATION OF LIABILITY: The information in this magazine is intended as a general presentation of the content included herein. While every effort is made by the publishers and editorial board to see that no inaccurate or misleading data, opinion or statements occur, GE cannot accept responsibility for the completeness, currency or accuracy of the information supplied or for any opinion expressed. nothing in this magazine should be used to diagnose or treat any disease or condition. Readers are advised to consult a healthcare professional with any questions. Products mentioned in the magazine may be subject to government regulation and may not be available in all locations. nothing in this magazine constitutes an offer to sell any product or service.

Clinical Value: Setting new Standards in Computed Tomography page 10

*A premium configuration of LightSpeed VCT.

TOCclarity_1.indd 2 2/17/09 9:04:40 AM

Publications Team:

J. Eric Stahre General Manager Global Computed Tomography

Nilesh Shah General Manager Global CT Marketing

John Allenstein Marketing Communications Manager CT and Advantage Workstation

Andrew Ackerman CT Cardiology Segment Manager

Mary Beth Massat Editorial Consultant

GE Contributors:

Andrew Ackerman CT Cardiology Segment Manager

Olivier Adda Cardiac CT Clinical Leader Marketing Europe

Bob Beckett CT Global Product Manager

Mark Bowman CT Advanced Applications Manager

David Dobson Academic and Children’s Hospitals Segment Manager

DeAnn Haas Global Cardiac CT Marketing Manager

Olga Imas, PhD Product Development Specialist CT Neurology Applications

Kelley Knutson CT Education Manager

Gina Larkin Cardiovascular CT Marketing Manager

Christoph Obermeier Cardiovascular Strategic Product Manager

Paula Pingel CT Segment Manager

Linda M. Pucek Oncology and Specialty CT Marketing

Saad Sirohey, PhD Neurology Product Manager

Shohei Takeuchi CT Marketing Manager

Jodi Young CT Education Manager

Weiwei Zheng Global CT Marketing Manager

3A GE Healthcare CT publication • Spring 2009

C O N T E N T ST A b L E O f

Beyond the Scan

Ultra-low Radiation Dose, Prospectively Gated Coronary CT Angiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Grassroots Campaign Creates Awareness for Lowering Pediatric Dose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Marketing your Radiology Practice . . . . . . . . . . . . . . . . . . . . . . . 67

Learn from the Experts: GE Healthcare’s CT Masters Series . . . . . . . . . . . . . . . . . . . . . . . 70

Technical Innovation

A Moment in Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

CT Sampling Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Solving the High Image Quality with Low Radiation Dose Paradox . . . . . . . . . . . . . . . . . . . . . . . . 50

Re-inventing the CT Imaging Chain . . . . . . . . . . . . . . . . . . . . . . . 53

GE Takes Leadership Role in Pediatric CT Imaging . . . . . . . . . 55

Technical Innovation: A Moment in Time page 42

Beyond the Scan: Ultra-low Radiation Dose, Prospectively Gated Coronary CT Angiography page 59


Gene Saragnese Vice President and General Manager, Computed Tomography, GE Healthcare

WelcomeSee more, know more, less dose. A catchy phrase, but what does it really mean? For GE Healthcare, it means re-examining the entire CT imaging chain in search of new methods and materials to deliver improved image quality. It means taking a leadership role to pursue a fundamental change in technology; one that answers today’s clinical needs but also tackles tomorrow’s challenges.

At GE Healthcare, we embrace the concept of “healthcare re-imagined” and think “what if.” What if we can let clinicians see more in a CT image or study than ever before? What if the system could bring new image clarity to CT? What if we could do this and also lower dose?

Well, we believe we have delivered on the “what if.” The culmination of 10 years of research, engineering innovation, and investment is the Discovery™ CT750 HD, a system that boldly takes CT imaging to a new level. It offers clinicians a competitive edge like no other imaging system before it . They see more through new levels of resolution and clarity.

G E H E A lT H C A r E n E W S W E l C O M E

They know more, applying more user-selectable energies and more views per rotation. They require less dose, scanning any part of the body in patients of all ages, including pediatrics.

Please join us and see for yourself as we unfold the Discovery CT750 HD story in the pages of CT Clarity. From a clinical perspective, Jean-louis Sablayrolles, MD, Chief of the CT and MrI Department, Centre Cardiologique du nord (CCn) talks about his experience as the first installed site in Europe to use the Discovery CT750 HD. After conducting over 2,500 studies, he sees first hand the great potential of this new imaging platform.

Also in this issue of CT Clarity, our engineers share their story on how they reevaluated the CT subsystems. The result is the Gemstone™ detector, the first new scintillator material in 20 years; the new Performix® HD X-ray tube that is the cornerstone to seeing more with less dose; a new data acquisition system that lets clinicians conduct studies

with the speed they need in today’s competitive and cost-constrained healthcare market; and, a new

reconstruction technique that reduces image noise and improves low contrast

detectability and image quality.

This issue is also loaded with information on existing applications and techniques on our lightSpeed® VCT series, from SnapShot™ Pulse for cardiac to Perfusion™ 4 for neuro to setting new standards in

pediatric imaging and dose optimization.

As you turn each page, you will experience our commitment to you – clinicians,

technologists, administrators, and patients – and our belief that by working together with

you, we can see a bright future in healthcare imaging. For us at GE Healthcare, this is the

meaning behind CT re-imagined. n



E V E N T S G E H E A lT H C A r E N E w S

GE looks forward to seeing you at the following events.

Calendar of Events

Date Conference Site City/State Country Web Link

Mar. 1-6Society of Computed Body Tomography & Magnetic resonance (SCBT-Mr)

Eden roc resort and Spa Miami Beach, Fl USA www.scbtmr.org

Mar. 6-10European Society of radiology (ECr)

Austria Center Vienna Vienna Austria www.myesr.org

Mar. 15-20Abdominal radiology Course

Grand Wailea Resort Hotel and Spa

Maui, HI USA www.uroradiology.org

Mar. 29-31American College of Cardiology (ACC)

Orange County Convention Center

Orlando, Fl USA http://acc09.acc.org

April 21-25The Society for Pediatric radiology (SPr)

la Costa resort and Spa Carlsbad, CA USA www.pedrad.org

April 25-30American Urological Association (AUA)

McCormick Place Chicago, Il USA www.aua2009.org

April 26-May 1American roentgen ray Society (ArrS)

John B. Hynes Veterans Memorial Convention Center

Boston, MA USA www.arrs.org

May 16-21American Society of Neuroradiology (ASNr)

Vancouver Convention and Exhibition Centre

Vancouver, BC Canada www.asnr.org/2009

May 19-22Stanford 11th Annual International Symposium on Multidetector-row CT

Hyatt regency San Francisco

San Francisco, CA USAhttp://radiologycme. stanford.edu/2009mdct/

May 29-June 2American Society of Clinical Oncology (ASCO)


Orlando, Fl USA www.asco.org

June 25-28radiation Therapy Oncology Group (rTOG)

Chicago Marriott Downtown

Chicago, Il USA www.rtog.org

July 16-19Society of Cardiovascular Computed Tomography (SCCT)

walt Disney world Dolphin Resort

Orlando, Fl USA www.scct.org

July 22-244th Annual Outpatient Imaging Center Conference (OIC)

JW Marriott washington, DC USA www.gehealthcare.com

Aug. 9-13AHrA by the Association for Medical Imaging Management

Mandalay Bay las Vegas, NV USA www.ahraonline.org

Sept. 10-12ESI 7th Annual Cardiovascular and Peripheral CT 2009

Bellagio las Vegas, NV USA www.edusymp.com

Sept. 21-26Transcatheter Cardiovascular Therapeutics (TCT)

Moscone Center San Francisco, CA USA www.tctconference.com

Oct. 2-6North American Society for Cardiovascular Imaging (NASCI)

Omni Orlando resort at ChampionsGate

Orlando, Fl USA www.nasci.org

Oct. 26-28The 10th Annual International Symposium on Virtual Colonoscopy

Hyatt regency reston reston, VA USAwww.bu.edu/cme/ calendar/calendar_home.html

Nov. 1-5American Society for radiation Oncology (ASTrO)

McCormick Place Chicago, Il USA www.astro.org

Nov. 14-18American Heart Association (AHA)


Orlando, Fl USA www.americanheart.org

Nov. 29-Dec. 4radiological Society of North America (rSNA)

McCormick Place Chicago, Il USA http://rsna2009.rsna.org

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G E H E A lT H C A r E n E w S A n n o u n C E m E n T S

world’s First High Definition CT Scanner Sets new CT Image Clarity Standard

The Discovery™ CT750 HD sets a new standard for CT clarity, delivering the vision and tools that allow clinicians to diagnose quickly and confidently. At its heart is the first new detector material in 20 years; one that is, quite literally, a gem. GE engineers discovered that, by replicating the molecular structure of a real garnet, they could develop a scintillator which is 100 times faster with up to 33% greater detail throughout the body and up to 47% greater detail in the heart. They had unlocked the secret. The proprietary GE Gemstone™ detector boasts the fastest primary speed in the CT industry and is the driving force behind the first of its kind “Gemstone Spectral Imaging” process.

To improve image quality, the laws of physics typically demand an increase in dose. GE Healthcare has engineered the exception. using Adaptive Statistical Iterative reconstruction (ASIr) on the Discovery CT750 HD improves image quality while reducing dose by up to 50% across the entire body for patients of all ages. The Discovery CT750 HD brings faster,

clearer images into today’s demanding healthcare environment and delivers the element patients and clinicians demand most: radiation dose reduction.

In addition to providing fine detail, allowing clinicians to see objects as small as a grain of sand, the improved spatial resolution of Discovery CT750 HD also reduces calcium blooming artifacts. Because of this, accurate stenosis quantification in coronary and vascular vessels is possible. The new CT system provides improved low contrast detectability (lCD) by up to 40% for improved visualization of low contrast structures down to 2 mm in size.

what began as a bold vision for the future of CT imaging has now become a reality. By providing high definition, low dose imaging, GE enables clinicians to discover the leading edge of CT clarity – the Discovery CT750 HD. n(note: Specifics regarding Gemstone Spectral Imaging are included in the CT Sampling Technology article on pages 45-49 in this issue).

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Simplifying Cardiovascular CTAutomation is the key to successful workflow


A n n o u n C e m e n T S g e h e A lT h C A r e n e w S

CardIQ™ Xpress 2.0 and CardIQ Function Xpress now offer new pre-processing and auto launch features that simplify workflow so clinicians can efficiently read cardiac CT studies. After acquiring single and multiphase data from a cardiac CT exam, the images are transferred to the workstation and data is placed in a queue. The application automatically computes the coronary vessel analysis, 3D angiographic, vessel tree, heart views, and functional data. With the new auto launch feature, a typical cardiac exam containing 3,000 or more images will load immediately, eliminating any waiting time and dramatically improving workflow.

CardIQ Xpress 2.0 also features a relative perfusion tool for users to visualize a diseased vessel and determine if there is a correlative rest perfusion defect. By utilizing

the IVuS-like feature, the clinician highlights the calcium and non-calcified plaque in the lumen with a volume rendered view to determine patency.

The new CardIQ Function Xpress software offers the benefit of left ventricular function analysis and also automatically calculates right ventricular function and right and left atrial volumes for a complete picture of the patient’s cardiac profile.

Implementation of CardIQ Xpress 2.0 and CardIQ Function Xpress software brings workflow and throughput to new levels of efficiency. n

Implementation of CardIQ Xpress 2.0 and CardIQ Function Xpress software brings workflow and throughput to new levels of efficiency.

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Marketing Tools Help Customers Succeed

G E H E A lT H C A r E n E w S A n n O U n C E M E n T S

new Toolkit Helps Increase Cardiac CTA Interpretation Skills

recognizing that most healthcare facilities engage in marketing and advertising, GE provides a vast assortment of marketing tools for customers to market their CT system to their referring physicians, communities and patients.

Tools specific to each CT system are designed to build awareness and drive patient volume – without the time and big-budget investment needed to create marketing tools from scratch. All marketing materials are available to GE CT customers via the GetCreative web site. Materials are in high-resolution, print ready formats and are ready to use as-is, including an extensive library of clinical images. Pieces can also be customized with customer logos and branding.

Target referring physicians and patients with customizable, print-ready marketing materials, such as:

Patient brochures;•

Print ads;•

Billboards;•

web banner ads;•

Posters;•

referring Physician direct mailers, postcards, • letters and emails;

Event invitations.•

The GetCreative web site includes a Knowledge Center with how-to guides, basic marketing tips and more to help customers get the most from their marketing materials.

To find out more about how you can access marketing materials online to announce and market your new GE CT system, contact your local GE sales representative or visit www.getcreative.gehealthcare.com. n

Designed for radiologists and cardiologists who want to learn how to interpret cardiac CT angiography (CTA) images, Interpreting the Heart: A visual guide using CardIQ™ Xpress is an educational toolkit containing 50 cardiac CTA case studies on DVD. Physicians will be able to develop their expertise with hands-on manipulation of a broad mix of exams, including 30 cases with cath correlations.

All cases include cardiac CTA impressions as well as a detailed description of findings under each reference image, which are provided by an expert interpreter. This toolkit enables physicians to gain confidence in their CTA interpretations in a cost-effective manner at their convenience. These 50 cases can be used toward level 1 and level 2 Cardiac CT credentials based on criteria established by the Society of Cardiovascular Computed Tomography (SCCT). Visit www.gehealthcare.com/cardiactoolkit for more information. n

The kit may be ordered by calling GE Healthcare at 1-800-886-0815. Outside the US, please contact your local GE sales representative.

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A n n o u n C E m E n T S

Introducing the LightSpeed VCT XTe,* Powered with HD Technologies

Building on the proven, clinical foundation of the LightSpeed® VCT, GE Healthcare introduces the LightSpeed VCT XTe* featuring advanced HD technologies from GE’s ultra premium CT scanner, the Discovery™ CT750 HD. The new LightSpeed VCT XTe* addresses several important clinical challenges including:

Improving patient care with dose reduction features such • as Adaptive Statistical Iterative Reconstruction (ASIR) and SnapShot™ Pulse;

Enhancing cardiac scan reliability through fast acquisitions • that enable short breath-hold for stable heart beat (5-Beat Cardiac™);

Extending the range for dynamic CTA and functional • assessment with VolumeShuttle™ and the new Volume Helical Shuttle;

Increasing throughput with faster reconstructions speeds; • and,

Providing an upgrade path for new and future capabilities.•

“The LightSpeed VCT XTe* brings advanced HD technologies to our largest installed base of CT customers,” says Dusty majumdar, marketing manager – Premium CT, GE Healthcare.

“These customers can be assured that they will not be left behind with their existing investment as GE continues to develop its CT platform.”

ASIR reduces image noise and improves low contrast detectability by up to 30%, and enables clinicians to reduce radiation dose by up to 40% without sacrificing image quality. Dose is also reduced by up to 83% in cardiac studies with SnapShot Pulse.

VolumeShuttle delivers twice the coverage in one acquisition and reduces dose up to 24% with a single contrast injection. The newly released Volume Helical Shuttle extends z-coverage to provide up to 312.5 mm for 4D CT angiography exams and up to 140 mm for perfusion analysis.

Robust cardiac scanning is made possible through adaptive ECG gating and real-time adaptive scan control with the 5-Beat Cardiac feature, further improving overall scan reliability for prospectively gated cardiac exams. Clinicians will experience greater levels of productivity and faster clinical throughput with Xtream™ HD, which nearly doubles reconstruction speed. n


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10

c l i n i c a l v a l u e

A GE Healthcare CT publication • Spring 2009

Centre Cardiologique du Nord (CCN) in Paris was the first hospital in Europe to install GE’s new generation Discovery CT750 HD. Jean-Louis Sablayrolles, MD, Chief of Cardiovascular CT and MRI, spoke with GE Healthcare about his clinical experience with the new scanner.

An interview with Jean-Louis Sablayrolles, MD, Chief of the CT and MRI Department, Centre Cardiologique du Nord (CCN)

Clinical Experience with the Discovery™ CT750 HD

Setting New Standards in Computed Tomography

D I S C O V E R Y C T 7 5 0 H D

Q: How long have you been using the Discovery CT750 HD scanner? How many and what type of studies have you performed?

Within the first five months of clinical use, we have scanned more than 2,500 patients. For an evaluation system, the new CT750 HD has been extremely reliable from day one of service. Right from the start, we scheduled all of our cardiac and vascular exams on the CT750 HD. However, we have performed routine diagnostic procedures on the system with excellent results, including neuro, abdomen, pelvis, virtual colonoscopy, etc.

Q: Can you describe your experience with the scanner?

Our hopes have become reality with this new generation of high-definition CT imaging. The extensive redesign of the image chain from generator, tube, detector, and new reconstruction algorithm has resulted in a new standard in imaging excellence. We can confirm that image quality is improved across the whole body, while at the same time we are continuously reducing dose.

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11

name of author

info about clinic, etc.




Jean-Louis Sablayrolles, MD, is a radiologist at Centre Cardiologique du Nord (CCN) in Saint-Denis, France, where he has been chief of the CT and MRI Department since 1988.

About the facility

CCN is a private clinic created by a cardiology group in 1973 in Saint-Denis, North of Paris, France, that is dedicated to the treatment of cardiovascular pathologies.With more than 180 beds, CCN performs over 1,000 cardiac interventions each year and is considered one of the finest cardiovascular centers in the world. The facility has performed CT cardiac exams since March 2000, and acquired a LightSpeed® VCT in December 2004, the LightSpeed VCT XT configuration in October 2006 and the Discovery™ CT750 HD in July 2008.

With the improved spatial resolution, we see more details than we have seen previously. For example, stents are imaged with more detail due to less blooming artifacts; higher contrast and spatial resolution enables us to visualize fine vessels and structures that we could not analyze with previous multi-slice CT systems.

Remarkably, using Adaptive Statistical Iterative Reconstruction (ASIR), dose reduction is achieved at the same time by lowering acquisition parameters such as 100 kVp with reduced mA as a standard protocol for heart imaging. Yet even with these dose reductions, we see improved image quality versus non-HDCT exams.

Q: Based upon your experience, are you able to see more and know more about the patient’s condition? And if so, how does this impact your clinical confidence/decision-making?

Clearly we can see more detail of the lesions, which improves our diagnostic confidence. In the example of stent visualization, we can analyze these challenging elements with more confidence than before. Coronary CTA has a strong negative predictive value, and we have high hopes that with this new generation of CT we may see improvements in regard to sensitivity and specificity. Better visualization of plaque will also have an increased role for treatment planning, such as coronary stenting of complex lesions. We already started using the CT750 HD for this purpose in our institution with good results.

Q: What in your opinion is the most important benefit of this new scanner? What previously unmet clinical needs has it fulfilled?

I can comfortably say this is the most versatile system I have ever used in my practice. Currently, I have benefited from the vast improvement in image quality and my patients have benefited from the lower radiation exposure compared to previous scanners.

The outstanding performance of the CT750 HD has already shown us in a short time the great potential of this platform. HDCT imaging will set new standards across applications and extend diagnostic confidence in computed tomography, whether that be in cardiology, oncology, neurology, or other clinical disciplines.

“ HDCT imaging will set new standards across applications and extend diagnostic confidence in computed tomography…”

– Dr. Jean-Louis Sablayrolles

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c l i n i c a l v a l u e D I S C O V E R Y C T 7 5 0 H D

Clinical images

CCN case studies

A 51-year old man was diagnosed with an occlusion of the femoral arteries. Figures 1 to 3 demonstrate full body high-resolution imaging capabilities with a 39 sec acquisition time and 163 cm of coverage on the Discovery™ CT750 HD. Note the outstanding high resolution detail of the peripheral vessels.

“ I can comfortably say this is the most versatile system I have ever used in my practice. Currently, I have benefited from the vast improvement in image quality and my patients have benefited from the lower radiation exposure compared to previous scanners.”

– Dr. Jean-Louis Sablayrolles

Figure 1

Figure 2 Figure 3

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D I S C O V E R Y C T 7 5 0 H D C l I n I C A l V A l u E

13

A 62-year old man had a follow-up scan after several interventions in the left coronary artery. low dose acquisition with prospective gating (SnapShot™ Pulse mode) delivered outstanding high resolution detail of the vessels along with instant visualization using only 1.9 mSv* (Figures 4 and 5).

A 52-year old woman was referred after a transthoracic ultrasound exam detected an abnormal mass in the left atrium. A retrospective-gated helical exam using the High Definition acquisition with ASIR reconstruction delivered high resolution detail of the coronary arteries along with complete functional and morphologic information of the myxoma using only 5 mSv* (Figures 6 to 8).

A 65-year old man had a follow-up scan after bypass surgery. low dose acquisition with prospective gating (SnapShot™ Pulse mode) delivered outstanding high resolution detail of the bypass for a coverage of 240 mm using only 4.5 mSv* (Figure 9). n

*Obtained by EuR-16262 En, using a chest factor of 0.017*DlP.

Figure 4

Figure 5

Figure 9

Figure 6

Figure 7 Figure 8

372912_10-13_EP.indd 13 2/17/09 9:10:18 AM

VR tree view with stents

Cross-section view in-stentVR view with stentCurved view LAD stent

Curved view stent

Discovery™ CT750 HD clinical images

Clarity without compromiseAn enhanced vision of care … across every anatomy.

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VR sinus Coronal sinus

Non-HDCT imageAbdomen CT750 HD image

VR neurovascular system

Clarity without compromiseAn enhanced vision of care … across every anatomy.

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Low-dose Cardiac CTA: Five-month Old with History of ApneaBy Christopher Dory, MD, Pediatric Radiologist, RADY San Diego Children’s Hospital and San Diego Imaging Medical Group

C L i n i C A L v A L u e P E d i A T r i C – L o w d o S E C A r d i A C

Patient history

A five-month old patient with a history of apnea and a family history of mitral valve prolapse was referred for evaluation. A prior echocardiogram indicated an inconclusive medical diagnosis of a congenital anomaly necessitating follow-up. A CT examination was ordered to rule out if the patient had a vascular ring and/or airway obstruction.

Acquisition protocol

Scanner ..............................LightSpeed® VCT with SnapShot™ Pulse

Slice thickness ................................................................... 64 x 0.625 mm

Rotation time ................................................................................... 0.35 sec

mA .................................................................................................................100

kVp ....................................................................................................................80

Travel distance ..........................................................................2 rotations

recon kernel .................................................................................. Standard

Heart rate .........................................................................................129 bpm

Calculated dose

Total exposure time .........................................................................0.8 sec

Total scan time ......................................................................................2 sec

dLP (using 32 cm phantom body) ............................... 6.99 mGy-cm

dLP (using 16 cm phantom body) .............................15.12 mGy-cm

CTDivol ................................................................................................1.00 mGy

effective dose .............................................................................. 0.59 mSv*

* obtained by iCrP newborn chest factor of 0.039 * dLP (using 16 cm phantom). reference: Annals of the iCrP, Volume 37, issue 1, March 2007.

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P E d i A T r i C – L o w d o S E C A r d i A C c l i n i c a l v a l u e

Clinical findings

The vascular ring demonstrated no abnormalities.

The patient was found to have an aberrant right subclavian artery and an atrial septal defect with an otherwise normal heart.

The development of SnapShot Pulse adds new possibilities to decrease radiation dose and obtain the same anatomic patient data.

– Dr. Christopher Dory

Christopher dory, Md, joined San diego imaging Medical Group in June 2006. He had previously practiced at the Children’s Hospital of the King’s daughters’ in Norfolk, Virginia where he served as chief of radiology and at the Children’s Hospital in Minneapolis, Minnesota. At the Children’s Hospital of the King’s daughters’ he was voted teacher of the year. His expertise includes pediatric interventional radiology, musculoskeletal imaging, and pediatric neuroimaging.

dr. dory graduated with honors from the US Naval Academy and subsequently served as a surface warfare officer before attending medical school. He completed medical school at the University of Utah School of Medicine.

His internship was at Mercy Hospital in San diego and residency in diagnostic radiology at the University of California, San diego. He served as chief resident while at the University of California, San diego. His fellowship in pediatric radiology was at the University of California, San diego and Children’s Hospital San diego. He is board certified in diagnostic radiology from the American Board of radiology and holds a certificate of Additional Qualification in Pediatric radiology.

Professional memberships:

• Alpha omega Alpha Medical Honor Society

• Society for Pediatric radiology

• Society for Pediatric Neuroradiology

• American roentgen ray Society

Follow-up diagnosis

As a result of the CT study, we were able to rule out the necessity for a surgical follow up. The patient and family were not subjected to an unnecessary surgical procedure and/or catheterization in order to diagnose this cardiovascular abnormality. The infant was treated for reflux disease and sent home.

Advantages of the scanner and application in this exam

due to the rapid scan time and non-invasive nature of CT, i chose to have the CT assessment performed to rule out mitral valve disease.

CT was a more attractive alternative for the patient’s family and the referring physician because of the dose lowering capabilities of the LightSpeed® VCT with SnapShot™ Pulse. with the assistance of GE Healthcare, i was able to set-up a new protocol specific to the patient’s age and size that significantly reduced dose versus a multi-phase examination.

This 64-slice LightSpeed VCT scanner is a quantum leap above and beyond what we were using a few years ago. The development of SnapShot Pulse adds new possibilities to decrease radiation dose and obtain the same anatomic patient data. n

Abnormal right subclavian artery

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c l i n i c a l v a l u e P E d i A T r i C – L o w d o S E C A r d i A C

Oblique MIP image of the chest Curved reformat of the LAD

VR depicting aberrant right subclavian Oblique image of the LAD/Cx

Coronal view of the chest with trachea and bronchi

This 64-slice LightSpeed® vcT scanner is a quantum leap above and beyond what we were using a few years ago.

– Dr. Christopher Dory

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C T P E r f u S i o n 4 & V o l u m E S H u T T l E C l i n i C A l V A l u E

Introduction

GE Healthcare CT Perfusion™ 4 software offers robust automated post-processing, tissue classification (visualization of infarct core and salvageable penumbra), and reliable quantification of blood

flow, blood volume, mean transit time, and contrast arrival delay or T0, over an extended 80-mm coverage when used with GE VolumeShuttle™ CT perfusion acquisition mode.

in addition to up to 24% less radiation dose, VolumeShuttle provides twice the brain coverage for a single bolus of contrast, which is both necessary for effective

stroke work up, and sufficient for triage to available approved therapies and clinical trials.1

massachusetts General Hospital has been successfully implementing a simple yet complete stroke work up consisting of:

1. unenhanced head CT to exclude hemorrhage or large completed infarct;

2. CT angiogram (CTA) of the head, neck, arch, and heart (optional in patients presenting with atrial fibrillation) to assess for vessel occlusion, stenosis, or left atrial/ventricular thrombus; and,

3. “Whole territory” CT perfusion using VolumeShuttle acquisition mode.

mri is typically also obtained, when time permits, for sensitive evaluation of infarct core with diffusion-weighted imaging. CTA is performed prior to

CT perfusion to identify the precise level of occlusion, which serves as a guide to accurately center the VolumeShuttle imaging coverage for the

CT perfusion portion of the scan. VolumeShuttle provides 80 mm of vertical (“z-direction”) coverage, which is optimized by accurate centering, and allows

for imaging of the entire anterior or posterior circulation territory, with overlap. This coverage is sufficient for accurate clinical diagnosis and therapy, and is achieved

at up to 24% less radiation dose than a 40 mm CT perfusion acquisition.

maximizing CT Perfusion Coverage for “Whole Territory” Stroke AssessmentBy Michael H. Lev, MD, Director, Emergency Neuroradiology and Neurovascular Lab; Shahmir Kamalian, MD, Research Fellow, Neuroradiology; and Frederick McNulty, RT (R) (CT) , Emergency Radiology CAT Scan, Massachusetts General Hospital

1. Schaefer PW, Barak Er, Kamalian S, Gharai lr, Schwamm l, Gonzalez rG, lev mH. Quantitative Assessment of Core/Penumbra mismatch in Acute Stroke. CT and mr Perfusion imaging Are Strongly Correlated When Sufficient Brain Volume is imaged. Stroke. 2008 nov;39 (11): 2986-92. Epub 2008 Aug 21 .

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c l i n i c a l v a l u e C T P E r f u S i o n 4 & V o l u m E S H u T T l E

Case 1

Patient history

74-year old female with past medical history of atrial flutter presented with right-sided weakness, severe aphasia, and left gaze deviation. iV tPA was given two hours after symptoms onset, with improvement in aphasia, although CTA showed persistent occlusion of the left middle Cerebral Artery (superior division, see arrow in figure 1) following treatment. Based on the CTA level of occlusion, CT perfusion scan was performed throughout the entire anterior circulation territory (see scout image in figure 2) using VolumeShuttle mode for complete 80-mm coverage.


Scan types performed: unenhanced CT, CT angiogram (CTA) of extracranial • carotid arteries and Circle-of-Willis (CoW), anterior circulation CT perfusion, mri, follow-up unenhanced CT

GE advanced applications used to diagnose: CT Perfusion• ™ 4 multi-organ – Brain Stroke Automatic protocol (post-processing used a pixel spatial averaging default value of 10)

Scanner ......................................................................................................... lightSpeed® vcT XT*

Scan protocol ...................................................................................................................... Perfusion

Scan type/slice thickness ......................................VolumeShuttle/16 images per 5 mm

Coverage .................................................................................................................................... 80 mm

rotation time .............................................................................................................................0.4 sec

Total elapsed time ....................................................................................................................90 sec

Total X-ray exposure time ....................................................................................................24 sec

mAs ............................................................................200 (500 mA at 0.4 sec gantry rotation)

kVp ...........................................................................................................................................................80

recon kernel .........................................................................................................................Standard

SfoV .................................................................................................................................................Head

DfoV .......................................................................................................................................................25

*A premium lightSpeed VCT configuration.

michael H. lev, mD, is a staff neuroradiologist, director of Emergency neuroradiology, neuro-CT, and director of the radiology neurovascular laboratory at massachusetts General Hospital, and associate professor of radiology at Harvard medical School. He is board certified in both internal medicine (1989) and radiology (1994), with a Certificate of Added Qualification in neuroradiology (CAQ, 1996).

His major research interests are in the field of neurovascular imaging, with special emphasis on CT angiography and CT/mr perfusion imaging of acute stroke and carotid occlusive disease. He serves on the editorial board of the American Journal of neuroradiology (http://www.asnr.org/ajnr/), and is a reviewer for numerous other radiology journals. He is neuroimaging project leader on the Partners HealthCare, niH funded, Special Program of Translational research in Acute ischemic Stroke (SPoTriAS) grant.

m. Shahmir Kamalian, mD, is a research fellow in the Department of neuroradiology at massachusetts General Hospital. He received his medical degree from Tehran university of medical Sciences, where he also completed his internship. His experience includes nearly two years in the Emergency Department at mehrad General Hospital (Tehran) and recently, a residency at Staten island university Hospital.

Dr. Kamalian is a member of the rSnA, American Heart Association/American Stroke Association, iranian American medical Association, the international Brain research organization, and the medical Council of i.r. of iran.

CT CTA

Figure 1

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Case 2

Patient history

49-year old male presented with acute onset of aphasia and face/arm weakness. Admission niHSS was 10. CTA showed a left middle Cerebral Artery m1 occlusion (arrow, figure 4) one and one-half hours after ictus. Based on the level of occlusion seen on the CTA, CT perfusion was performed throughout the entire anterior circulation using VolumeShuttle mode lightSpeed® VCT XT* scanning for 80 mm of vertical coverage (scout image, figure 5). mri was performed 15 minutes later.


Scan types performed: unenhanced CT, CTA of extracranial • carotids and CoW, CT perfusion, mri, follow-up unenhanced CT

GE advanced applications used to diagnose: CT Perfusion• ™ 4 multi-organ – Brain Stroke Automatic protocol (post- processing used a pixel spatial averaging default value of 10)

Scanner .....................................................................lightSpeed VCT XT*

Scan protocol ............................................................................... Perfusion

Scan type/slice thickness ......VolumeShuttle/16 images per 5 mm

Coverage ............................................................................................. 80 mm

Rotation time ......................................................................................0.4 sec

Total elapsed time .............................................................................90 sec

Total X-ray exposure time .............................................................24 sec

mAs .....................................200 (500 mA at 0.4 sec gantry rotation)

kVp ....................................................................................................................80

recon kernel ..................................................................................Standard

SfoV ..........................................................................................................Head

DfoV ................................................................................................................25

Contrast protocol

Contrast ....................................................................370 mg/ml strength

Contrast injection rate ............................................................... 7 ml/sec

Total contrast amount ......................................................................45 cc

Saline injection rate ..................................................................... 4 ml/sec

Total saline amount ............................................................................45 cc

Contrast protocol






Findings and outcome

Admission CBV and CBf maps show a small infarct core with markedly decreased contrast delivery, and a matched admission DWi lesion. There is a moderately larger region of abnormal but less severely deranged CBf and mTT, consistent with ischemic penumbra (figure 2). Because there was no vascular recanalization in this case, the infarct has progressed in size on the follow-up unenhanced CT scan, more closely matching in extent the admission penumbral lesion (figure 3).


Figure 2

CBV

CBF

MTT

Figure 3

DWI Follow-up CT

372912_19-23_EP.indd 21 2/17/09 9:22:59 AM


c l i n i c a l v a l u e C T P E r f u S i o n 4 & V o l u m E S H u T T l E

Findings and outcome

admission cBv and cBF maps show a small deep infarct core with markedly decreased contrast delivery and a matched admission DWi lesion. There is a larger region of abnormal but less severely deranged CBf and mTT, consistent with ischemic penumbra (figure 5).

Perfusion mismatch and proximal large vessel occlusion seen on CTA necessitated intra-arterial (iA) thrombolysis. Successful recanalization of the left m1 occlusion, with residual cutoff

Figure 6. Angiography

in addition to up to 24% less radiation dose, VolumeShuttle™ provides twice the brain coverage for a single bolus of contrast…

at the post rolandic branch, was achieved four-and-one-half hours after stroke onset (figure 6). The patient was discharged to a rehabilitation hospital with niHSS of five after four days. With recanalization there was no lesion growth; final infarct size, as shown in the follow-up CT, was similar to that of the admission mr DWi lesion (figure 7), but less than that of the admission CBf/mTT penumbral lesions. incidental note is made of small deep post-recanalization hemorrhage on follow-up cT.

Figure 4

CT CTA

Figure 5

MTTCBV CBF

Figure 7

DWI Follow-up CT

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Figure 8

CT

Figure 9

CBF

CBV

MTT

Figure 10

DWI Follow-up CT

Case 3

Patient history

46-year old male with history of hypertension presented with sudden onset of severe vertigo, nausea, and vomiting. He was brought to the hospital 2 hours and 15 minutes after symptom onset with an niHSS of three. CTA showed probable dissec-tion of the dominant distal extracranial left vertebral artery (figure 8). unenhanced CT showed early ischemic hypoden-sity. Based on the CTA results, CT perfusion was performed throughout the entire posterior fossa using VolumeShuttle mode lightSpeed® VCT XT* scanning for 80 mm of vertical coverage (scout image, figure 9).


Scan types performed: unenhanced CT, CTA of extracranial • carotids and CoW, CT perfusion, mri, follow-up unenhanced CT

GE advanced applications used to diagnose: CT Perfusion• ™ 4 multi-organ – Brain Stroke Automatic protocol (post- processing used a pixel spatial averaging default value of 10)

Scanner .....................................................................lightSpeed VCT XT*

Scan protocol ............................................................................... Perfusion

Scan type/slice thickness ......VolumeShuttle/16 images per 5 mm

Coverage ............................................................................................. 80 mm

rotation time ......................................................................................0.4 sec

Total elapsed time .............................................................................90 sec

Total X-ray exposure time .............................................................24 sec

mAs .....................................200 (500 mA at 0.4 sec gantry rotation)

kVp ....................................................................................................................80

recon kernel ..................................................................................Standard

SfoV ..........................................................................................................Head

DfoV ................................................................................................................25

Contrast protocol






Findings and outcome ischemic lesions of both cerebellar hemispheres are present on the CBf, mTT and CBV maps (figure 9), without a significant degree of mismatch. Given the low niHSS and early ischemic signs on the unenhanced CT, thrombolytic therapy was deferred. The admission mr DWi and follow-up unenhanced CT findings matched the admission CT perfusion findings (figure 10). n


372912_19-23_EP.indd 23 2/17/09 9:28:11 AM


CT Simulation Advances Proton Beam Therapy by Helping Overcome Challenges with Tumor Motion

c l i n i c a l v a l u e L i G H T S P E E d R T 1 6

Making state-of-the-art proton therapy available to more cancer patients is the goal of ProCure Treatment Centers, inc., headquartered in Bloomington, iN. The company partners with hospitals and radiation oncology practices to develop and operate proton therapy centers, using a standardized model that ProCure says may improve both the clinical practicality and cost effectiveness of this complex and expensive radiation treatment technique.

372912_24-26_EP.indd 24 2/17/09 9:28:56 AM


L i G H T S p E E d R T 1 6 c l i n i c a l v a l u e

proton therapy is a form of external beam radiation that uses non-electromagnetic ionizing radiation to treat solid tumors. Because it can be targeted more precisely at the tumor, the proton beam can deliver an increased dose of radiation with less damage to normal tissue than other forms of external beam radiation. Among the cancers treated with this technique are: prostate cancer, base of skull tumors, ocular melanoma, paranasal sinus tumors, non-small-cell lung cancer, and certain pediatric tumors.

A greater need for precision

“precision in tumor imaging and treatment planning is critical to proton therapy,” says Niek Schreuder, MSc (med) dABR, proCure’s senior vice president of medical physics and technology. “The whole process of proton therapy begins with imaging. it is much more dependent on excellent image quality and accurate density information when compared to other traditional radiation treatment techniques using electromagnetic ionizing radiation.”

For that and other reasons, proCure selected the LightSpeed® RT16 wide bore CT simulator system from GE Healthcare to assist in proton therapy planning. The system was installed in February 2008 in proCure’s Training and development Center, the first facility in the world to provide proton therapy training using real life size equipment and simulators. in addition to training personnel for its partnership sites, the Center is also used for training radiation therapy students from the local state college.

proton therapy works by harnessing the unique ability of protons to release the majority of their energy directly at the tumor site. Unlike photons, protons stop at a certain depth. “With protons, if you go too shallow, you’ll miss some of the target. if you go too deep, you may hit critical structures beyond the target,” explains Ben Harris, MS, dABR, proCure’s director of medical physics at the Training and development Center.

“The high resolution and tissue representation provided by the LightSpeed RT16 wide bore CT simulator images are critical factors in helping the radiation oncologist determine the exact treatment parameters to avoid those problems,” he says.

Overcoming the challenge of tumor motion with 4D imaging capabilities

“Accounting for tumor motion is another critical aspect of proton therapy planning,” says Schreuder. “A moving target for protons is a significant challenge because of the sensitivity of the beam path to density changes. A proton beam calibrated to deliver a high dose of radiation to a lung tumor when it reaches a certain depth in the lung, will release that load far deeper in the patient’s body if the tumor shifts out of the beam due to respiration motion.”

For that reason, the Center configured both the LightSpeed RT16 system and their Oncology Workstation with Advantage 4d® respiratory gating capabilities, GE’s exclusive tumor motion assessment software. “We have to know how the tumor is moving on a day-to-day basis. The only way to do that is through 4d analysis,” says Schreuder.

Improved workflow

Tumor motion assessment is one of many treatment planning tools available to the Center on their Oncology Workstation software platform, according to Lead Radiation Therapist John Smith, RTT. They also use AdvantageSim™ Md, GE Healthcare’s leading simulation and localization software.

“Advantage SimMd is a time saver and allows us to efficiently perform all of the front-end work in the treatment planning process up to dose calculation and plotting the isodose curves,” says Smith.

“Having such a productive workflow tool is critical in proton therapy,” says Schreuder. “The Oncology Workstation helps the Center use the proton therapy system more efficiently. We draw tumor volumes on the 4d workstation and send them to the planning system, which is then used to generate the treatment plan.”

The Center’s workflow is completely paperless, says Harris. The data from the LightSpeed RT16 and Advantage SimMd workstation feeds directly and seamlessly into the Center’s oncology RTpS and pACS environment. “There’s no paper involved because paper slows down the treatment process and is always at risk of getting lost,” he says. “Even the notes made by the radiation physicist on the characterization of the scan are captured electronically so they are always available wherever you are – even across the globe.”

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c l i n i c a l v a l u e L i G H T S p E E d R T 1 6

“proCure’s mission is to expand the availability of proton therapy worldwide by reducing the time, cost, and effort necessary to create these facilities,” says James Jarrett, vice-president of clinical partnerships. This is accomplished by providing a comprehensive solution for the design, construction, financing, staffing, training, and day-to-day operations of each center, including best-in-class diagnostic, treatment planning, facility management, and imaging integration systems and software.

“The development of a proton therapy center is a huge undertaking,” says Jarrett. “people want advice and expertise on what works and what doesn’t. We believe that working with companies like GE Healthcare can help us answer those questions and show our customers the pathway to cutting-edge cancer treatment.”

He says that proCure is especially interested in tapping into GE’s transformational resources, like the performance Solutions group, for assistance in optimizing facility design, workflow processes, technology utilization, and staff development. “The most important assets at any Center are the people who work there,” says Jarrett. “We see performance Solutions as providing tools and methodologies for continuous improvement.”

Gaining insights into GE’s vision for the future of imaging and radiation oncology will also be an advantage, says Jarrett. “it’s always nice to run to where the ball is going to be,” he says. “Knowing where things are heading will be helpful to proCure going forward as we continue to develop innovations in proton therapy.” n

Flexibility to position patients accurately

proton therapy planning also requires greater precision in patient positioning, says Schreuder. The large bore of the 16-slice LightSpeed RT16 system helps in that regard. during treatment, the proton beam aperture is placed approximately 2 to 5 cm from the patient’s skin, much closer than the 40 cm distance used in conventional radiation therapy. With the greater potential for interference between the equipment and the patient and the greater beam alignment sensitivity, the patient has to be imaged in the exact profile that will be used for treatment.

“We need the large bore scanner,” Schreuder says, “because it provides more free space to position the patient so that the same form and shape can be reproduced accurately on the treatment bed a few days later.”

A softer learning curve

Smith is in charge of developing and implementing the training protocols that will be used to train radiation therapists for all proCure proton Therapy Centers nationwide. He particularly appreciates the simplicity of operating the LightSpeed RT16 system. “it’s a great machine. The menus are where you need them and the information you want to see most readily is always available on the main screen. it’s very easy to teach people – the system softens the learning curve quite a bit.”

The pathway to cutting edge cancer care

proCure’s first proton therapy center is being built in Oklahoma City, OK and is scheduled to open in 2009. proCure has three additional proton therapy centers under development. At present, there are only five proton therapy facilities in the United States, treating about 5,000 patients each year. The company says that there are long waiting lists at these facilities and that upwards of 100,000 patients annually might benefit from the therapy if they had access to it.

“ The high resolution and tissue representation provided by the LightSpeed RT16 wide bore CT simulator images are critical factors in helping the radiation oncologist determine the exact treatment parameters…”

– Ben Harris, MS, DABR

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27


A GE Healthcare MR publication • Spring 2009

C A R d i A C C T A – L o w d o S E

A Promising New Tool for Myocardial evaluation By Erasmo de la Peña-Almaguer, MD, FACC, Director, Cardiovascular Imaging Center, Cardiac and Vascular Diseases Institute, Hospital San José, Tec de Monterrey

Patient history

The patient presented with atypical chest pain six months after having undergone a dual stent placement for a chronic total occlusion of the RCA.

An acute obstruction of the LAd with presence of thrombus was also present.

A moderate lesion of the first diagonal was also present but treated with medical therapy.

A coronary CT angiography (CTA), 3T Stress MR Perfusion using Fiesta and MdE, and a rest-stress MiBi was performed.

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28

c l i n i c a l v a l u e C A r d i A C C T A – L o w d o S E


Scanner .............................................................................LightSpeed® vcT

Slice thickness ................................................................... 64 x 0.625 mm

Pitch .............................................................................................................0.2:1

rotation time ................................................................................... 0.35 sec

mA ..................................................................................................................739

kVp .....................................................................................................................12

recon kernel ..........................................................................................Detail

SFoV ..........................................................................................................Large

Heart rate ............................................................................................55 bpm

Contrast protocol

injection rate .....................................................................................5 cc/sec

Contrast amount .... 60 cc with a Saline flush of 30 mls at 5 cc/sec

Background

To assess viability and detect ischemia in the area of the first diagonal, a comparison study was done with rest-stress MiBi and stress Mr.

in addition, the patient underwent a prescribed contrast-enhanced coronary CTA on a GE Healthcare LightSpeed VCT scanner. The exam was immediately processed and reviewed on a GE Advantage workstation® equipped with CardiQ™ Xpress 2.0 Elite.

Erasmo de la Peña-Almaguer, Md, FACC, director, Cardiovascular imaging Center, Cardiac and Vascular diseases institute, Hospital San José, Tec de Monterrey, Mexico is a clinical cardiologist with post-doctoral training in cardiovascular imaging. He is trained in multiple areas of cardiovascular imaging, including nuclear medicine, Mr, and CT. He studied at the Brigham and women’s Hospital, Harvard Medical School, and Stanford University Medical Center. He co-chairs the Latin American Chapter of the Society of Cardiovascular Mr (SCMr) and is a reviewer for the international Journal of Cardiovascular imaging (North American Society of Cardiac imaging).

Figure 1. Rca Figure 2. laD

Clinical findings

The rest perfusion tool helped us identify a non-transmural Mi on the anterior wall as well as on the inferior wall in the area surrounding the LAd stent. This correlates well with the clinical data received from the Mri study.

Advantages of using CardIQ Xpress 2.0 Elite

The application was used to assess the CTA data to analyze rest perfusion, a capability once available only via Mri and nuclear imaging. As this case demonstrates, CT rest perfusion is a promising technique for assessing areas of hypo-perfused myocardial tissue using a low-dose prospective technique. n

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29A GE Healthcare MR publication • Spring 2009

C A R d i A C C T A – L o w d o S E c l i n i c a l v a l u e

Figure 3. Tesla rest perfusion MR using 3d FiESTA sequence. The MR shows a non-transmural Mi in the inferior wall, combined with a small zone in the center of the anterior wall, underneath the zone of the stent (LAd Territory).

Figure 4. Rest MiBi perfusion showing the inferior wall and small anterior wall defects.

Figure 5. CT rest perfusion image obtained with CardiQ Xpress 2.0 Elite, showing region of interest as compared to MR and rest MiBi with delayed contrast enhanced MiBi.

…CT rest perfusion is a promising technique for assessing areas of hypo-perfused myocardial tissue using a low-dose prospective technique.

– Dr. Erasmo de la Peña-Almaguer, FACC

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30



Battlefield wounds are complex cases that often test the limits of man and machine. These limits continue to expand as advancements in medicine and technology enable today’s soldiers to survive injuries that were often fatal in prior wars.

T r a u m a i m a g i n g

cT marches to the Front lines of Trauma ImagingBy Irwin Feuerstein, MD, Co-director of Cardiovascular CT and Director of Peripheral Vascular Imaging, Walter Reed Army Medical Center

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About the facility

The Walter Reed Health Care System (WRHCS) provides comprehensive healthcare for more than 150,000 soldiers, other service members, family members, and retirees in and around Washington, DC. Its hub is Walter Reed Army Medical Center, the clinical center of gravity of American military medicine.

WRHCS provides a full range of services for patients, from routine primary care to the most sophisticated, high-tech specialty care. It is patient-focused and dedicated to streamlining each patient’s passage to the appropriate level of care they need. Each facility within the system is a valuable partner and brings its unique expertise to bear on healthcare delivery.

The system’s staff of 6,000 includes more than 600 Army physicians. Half of them are in training in more than 40 graduate medical specialty programs. Walter Reed trains the majority of the Army’s physician subspecialists. In addition, it conducts training for many nursing and enlisted medical specialties. Its status as a worldwide referral center for patients with the most complex and challenging illnesses supports the high quality of its educational missions, and sustains the capabilities of its clinical staff.

WRHCS is also the Army’s leading center of clinical research and innovation, attracting annual research support for such efforts as prostate disease, coronary artery disease reversal, comprehensive breast care, therapy of traumatic brain injury, amputee care and limb salvage, advanced diabetes management, technical advances in robotic surgery, nursing care delivery, evaluation of balance disorders, telemedicine, treatment of chronic viral hepatitis, and many other programs.


American soldiers are brought back to Walter Reed Army Medical Center (WRAMC) in Washington, DC, for advanced diagnosis and surgery. We see a range of injuries, from complex fractures to blast and penetrating trauma. Many have been stabilized with fixation devices or casts as a result of their initial evaluation on the battlefield, in the cache, or at Landstuhl Regional Medical Center in Germany, and a large number have had initial surgery to control acute bleeding, including arterial injuries.

Accurately detailing the complexity of injuries on a patient surrounded by or containing metal is a challenge we face weekly. Under the careful leadership of COL Michael P. Brazaitis, MD, Chairman of the Department of Radiology, CT scanning now plays a crucial and growing role in the diagnosis and treatment of injured soldiers.

Today, at WRAMC, we rely on GE Healthcare’s LightSpeed® VCT XT,* 64-slice CT scanner for advanced diagnosis of battlefield wounds. The subtleties we look for include vascular flaps, stenoses, transections and occlusions, bony fractures, and soft tissue injuries. Many of our patients have had arterial repairs, often including graft reconstructions. So we also evaluate the grafts to see if they are patent and whether they need to be revised. Armed with this information, our surgeons have a greater opportunity for surgical success. Yet, not all patients require additional surgery, and the advanced imaging allows identification of patients for conservative management with greater confidence that occult vascular injury will not contribute to long-term complications.

“With our 64-slice CT scanner, we can add a tremendous amount of information to the patient assessment with pictures that are truly amazing,” Dr. Brazaitis says.

Take it to the limit

Overall, our team is quite impressed with the capability of the LightSpeed VCT XT* on a number of fronts. One clear advantage is that we can perform a complete head-to-toe angiogram when needed. With GE’s 2000 mm table, I can image from the skull to the toes and generate beautiful diagnostic images all the way through. Examinations with multi-extremity injuries as well as tall or large-sized patients are potentially difficult imaging studies to conduct, but can be completed with persistence and a little creativity.

When performing a CT angiogram (CTA) on our 64-slice scanner, we can image the neck, chest, abdomen, pelvis, both legs, and usually one but sometimes both arms with just a few cc more contrast than required for a CT study of only one leg. To conduct a similar study in the cath lab, where nearly all patients were sent prior to installation of the 64-slice CT scanner, patients could receive 200 to 300 cc of contrast to visualize all of the vascular structures.

These scans are interesting and fun to conduct because of the variety of parameters we can manipulate to optimize the acquisition. Most of the patients are aggresively hydrated with large circulating volumes, and with leg injuries there is often fast or asymmetrical flow. Timing is therefore a challenge, as is the imaging of multiple body parts. GE’s 40 mm detector delivers 0.35 mm isotropic resolution in all scan modes and at all scan speeds so that we can scan the total patient faster than before. And speed is important when scanning soldiers with fast flow and who are in pain.

*A premium LightSpeed VCT configuration.

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With the LightSpeed® VCT XT,* we can image through almost all reasonably sized metallic objects, such as bilateral external fixation devices and intramedullary rods, and still generate amazing images. When we have to, we can increase to 140 kVp and compensate with a denser contrast material or faster injection rate. Even at this rate, the 8 MHU tube does not overheat. When coupled with the scanner’s 100 kW generator, the scanner enables faster gantry rotations and greater anatomical coverage.

The LightSpeed VCT XT* helps us balance radiation dose with diagnosis. The system’s Smart mA feature adjusts the mA to changes in body size and helps us utilize dose-saving features, particularly to reduce dose when imaging extremities such as the legs. With the ability to reach 800 mA, we can slice through thick body parts or large-sized patients with the same contrast injection. This system provides excellent image quality along with dose-saving features.

Even with the presence of shrapnel, the system captures excellent images of the neck and allows for the detection of pseudoaneurysms, which is a challenging diagnosis. Yet, we can scan through drains or suction devices to identify numerous injuries such as flaps, intimal damage, transections from bones, and missile trajectories.

Ninety percent of the time or more, we get the information that our surgeons need to manage their patients, and with a CTA on the LightSpeed VCT XT,* we can obtain the right diagnosis.

Every picture tells a story

The wounded soldiers at WRAMC typically have numerous residual fragments from various dense objects embedded in their wounds. On older scanners, the dense objects might have resulted in an uninterpretable or falsely negative imaging study. Prior to leaving WRAMC, COL David L. Gillespie, MD, FACS, who was Chief and Program Director, Vascular Surgery Service, preferred CTA for diagnostic work-up over angiography. He explains, “We can image through many different types of metal and view other substances like rocks and dirt with minimal artifacts.

We can retrace images, view 3D reconstructions, and generate transverse views, such as MIPs and MPRs, to view anatomic detail in a more relaxed mode versus performing the evaluation on-the-fly in the cath lab.”

Patients benefit as well with a noninvasive CTA. Compared to angiography, they experience less pain, receive less contrast, and endure a shorter procedure – often 15 minutes on the CT scanner rather than one hour in the cath lab. Plus, there are no catheter related complications.

T R A U M A I M A G I N G

Today at WRAMC, we perform the majority of diagnostic vascular work-ups on the 64-slice CT scanner. Dr. Gillespie believes that CTA is a remarkable single assessment tool. “We have more angles and views with CTA; therefore, I find it incredibly useful for image evaluation and interventional planning,” he says. In the end, better images result in a more complete and accurate patient assessment.

Breaking new ground

Advanced visualization and 3D reconstruction is performed on GE’s Advantage Workstation.® An outstanding workstation that I’ve used for working with these patients, it makes the hard things easy and the seemingly impossible possible. Although the workstation reconstructs images automatically, we can turn off certain features like the automatic tracking to work around shrapnel, pins, and clips.

Figure 1. Curved multiplanar reformat of the posterior tibial artery shows a patent vessel after reconstruction of the artery with an interposition graft. Despite large and dense metallic external fixation pins, the artery is clearly demonstrated all the way down to the toes.


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33




In particular, curved MIPs are most useful for viewing difficult injuries, such as an artery that is pulled into a wound or one that endures missile trauma. It is not unusual for a single study to contain 5,000 individual slices after numerous reconstructions. For these studies, the Advantage Workstation® is invaluable; I can do things I can’t do on different workstations. Seeing things in 3D really does make a difference. Even though all the information is theoretically on the 2D images, it is more obvious and easier to understand on the curved miPs or slab MIPs. With the vascular mapping provided by this advanced scanner, our surgeons can plan multiple flaps to a wound that fails to heal or follow the vascular supply in a leg that has most of the small vessels destroyed.

At WRAMC, we are using the LightSpeed® vcT XT* to visualize areas with extensive damage and break new ground with CT imaging. The trauma cases here are extraordinary – I’ve never seen them anywhere else. Yet, through all of these imaging challenges we don’t lose sight of the end result. Our goal is to manage the patient acutely and use the imaging data for reconstructive surgery while sparing them from unnecessary interventions or additional surgeries. n

Figure 2. Volume rendered image of the lower extremities demonstrates the complex nature of the injuries with external fixation devices, drains, antibiotic beads, casting material, and complex fractures and soft tissue injuries. Despite extensive metal and other interventions, with 140 kVp scanning the arteries are clearly depicted and the relationships of the vessels to the other structures can be clearly understood and transmitted to the surgeons for management.

Figure 3. Curved multiplanar image through the superficial femoral artery shows two separate small pseudoaneurysms, one from each side of the artery that was penetrated by shrapnel. This was not suspected by clinical examination. Note that despite the presence of metallic fixation devices externally and shrapnel internally, there is no difficulty seeing and interpreting the vascular anatomy. The artery was subsequently surgically repaired.

Patients benefit as well with a noninvasive CTA. Compared to angiography, they experience less pain, receive less contrast, and endure a shorter procedure…

– Dr. Irwin Feuerstein


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compact, Multi-detector cT Answers the Imaging Challenges for Japan’s Most Modern Hospitals

b r I G H T S p E E d S E l E C T

“ We are seeing a tremendous clinical benefit as our technologists can now provide 3d Mpr images immediately after the exam by accessing applications right on the operator’s console.”

– dr. Masaki Matsusako

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About the facility

Japan’s first modern hospital, St. Luke’s International Hospital (Tokyo) was founded in 1902 by a dedicated missionary, Dr. Rudolph Bolling Teusler. A statement attributed to Dr. Teusler explains the philosophy of St. Luke’s as, “This hospital is a living organism designed to demonstrate in convincing terms the trans-muting power of Christian love when applied in relief of human suffering.”

There are three major segments for medical care at St. Luke’s International Hospital.

1. Comprehensive Centralized Services: St. Luke’s is proud to be the first hospital in Japan to develop a centralized approach to radiology, anesthesiology, pathology, and clinical laboratory, thereby achieving optimum efficiency in the delivery of diagnostic and therapeutic services.

2. Ward Residency and Attending Doctor System: St. Luke’s residency and attending doctor system affords invaluable opportunities for onsite learning. Under the supervision of attending doctors, full-time residents stationed in the wards of internal medicine, surgery, pediatric, and obstetrics and gynecology are directly responsible for the care of inpatients. Specialized training and mentoring are available from chief and senior residents in each ward.

3. Clinical Preventive Service: One of St. Luke’s core beliefs surrounding patient care is that prevention is just as important as the treatment of disease or injury, and that clinicians can and should exercise leadership in the ongoing improvement of public health services. In 1954, St. Luke’s became the first hospital in Japan to provide preventive examinations for company workers. Since then, these services have expanded, from one-week, three-day in-hospital examinations to one-day ambulatory check-ups, brain scans, lung cancer screening, prenatal education and post-partum care for mothers and infants, including Well Baby Clinics.

In 2002, St. Luke’s celebrated its 100th anniversary and today continues to explore the cutting edge of medicine and technology.

B R I G H T S P E E D S E L E C T

For many hospitals, space is at a premium. Replacing older systems with newer technology is often hampered by the fact a site does not have the additional space needed for a larger system.

Recognizing this, GE Healthcare introduced a new family of CT systems that provide the power of advanced imaging capabilities with a compact footprint and easy-to-use interface. With LightSpeed® VCT technology inside, the BrightSpeed® Select family of CT systems delivers exceptional images, fast-paced productivity and remarkable reliability of GE’s industry-leading LightSpeed scanners.

So when it was time for St. Luke’s International Hospital (Tokyo, Japan) to upgrade a GE Healthcare HiSpeed® NX/i CT scanner, the facility sought a system with advanced technology that could fit into the existing CT room without undergoing reconstruction. According to Masaki Matsusako, MD, Katsunori Oikado, MD, and Takayuki Suyama, RT, the facility examined several 16-slice scanners based upon image quality, ease of use, and dose performance.

The answer became clear after evaluation of the BrightSpeed Elite Select, a 16-slice CT system. Requiring less than 234 square feet (12'11" x 19'3") St. Luke’s discovered they could install the system into the existing space of the two-slice HiSpeed NX/i CT scanner.

Clinical capability and patient throughput were additional considerations. The facility already had a LightSpeed16. Dr. Matsusako knew that any significant difference in clinical capability between two scanners could compromise the facility’s ability to handle its high patient volume.

Again, the BrightSpeed Elite Select rose to the challenge. With the same easy-to-use and familiar interface as GE’s LightSpeed systems, St. Luke’s discovered that technologists could easily move between both CT systems from an operational standpoint.

“BrightSpeed Elite Select is a well-balanced system with a very accurate mA modulation,” says Suyama. “One technologist can operate it without sacrificing patient throughput.”

The BrightSpeed Elite Select contains many of the same technological advancements found in the highly regarded LightSpeed VCT. For instance, GE’s exclusive Volara™ 24-bit Digital Data Acquisition Systems (DAS) delivers high processing power for high-resolution images and low-dose performance. It reduces noise up to 33%, resulting in proven image quality in signal-starved areas, such as shoulders, hips, and large patients.

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In fact, St. Luke’s radiology team prefers the BrightSpeed® Elite Select for head, pediatric, and interventional procedures because of the system’s image quality and dose performance. For all emergency patient exams, it is the scanner of choice due to usability and flexibility. Consistent, superb image quality is equally attained by both seasoned and new technologists.

Dr. Oikado notes that the BrightSpeed routinely performs 1.25 mm helical scans, which is particularly beneficial for chest exams. “With the BrightSpeed’s rapid acquisition time, we see fewer motion artifacts around the ascending aorta and left lung,” he adds.

Plus, technology such as the Freedom Workspace table and the Xtream™ FX workflow and productivity engine make the BrightSpeed Elite Select stand out at St. Luke’s. For instance, lightning-quick image reconstruction is just one key feature that impacts the workflow productivity of both technologists and radiologists.

Explains Dr. Matsusako, “We are seeing a tremendous clinical benefit as our technologists can now provide 3D MPR images immediately after the exam by accessing applications right on the operator’s console. This is especially useful for the road mapping of interventional procedures such as RF ablation.”

B R I G H T S P E E D S E L E C T

Features such as auto segmentation tools and one-touch protocols help St. Luke’s technologists seamlessly handle large datasets without sacrificing time. The impact has already been felt. “We now perform 10% more exams each day than with our previous scanner,” adds Mr. Suyama. Each day, the department conducts approximately 50 of its 90 exams on the BrightSpeed Elite Select.

“Great image quality is really the biggest benefit of using our BrightSpeed system,” states Dr. Oikado. In a hospital that consistently uses advanced applications, including AutoBone® and the Add Vessel tool in VolumeViewer,™ it stands to reason that image quality would be a major factor in the type of CT scanning system being depended on for routine radiology exams.

With superb image quality, improved workflow, and usability, the BrightSpeed Elite Select has helped St. Luke’s deliver a modern solution into a compact space for maximum results. n

Takayuki Suyama, RT Katsunori Oikado, MD Yukihisa Saida, MD, Chief Radiologist

Masaki Matsusako, MD

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S n A p S H o T p u l S E

By Jean-Pierre Laissy, MD, Professor, Cardiovascular and Interventional Radiology, and Jean-Michel Serfaty, MD, Assistant Professor, Cardiovascular and Interventional Radiology, Hospital Bichat and Gregoire Avignon

low-dose aorta, iliac and Femoral Angiography with prospective ECG-gated CT

Aortic diseases such as aortic dissection (type A and B) or Marfan syndrome require coverage of the entire aorta, iliac, and femoral arteries with clear delineation of vessel wall and intimal flap during the study acquisition. Cardiac non ECG-gated Computed Tomography has been proposed for these types of examinations but results in a higher radiation exposure to the patient, which is a consideration in clinical use. As a consequence, most aorta CT studies are currently performed using conventional retrospectively gated helical aquisitions.

SnapShot™ pulse, GE Healthcare’s step-and-shoot technique, has been successful in acquiring small thoracic volumes to assess coronary arteries at a low radiation dose. This method, based on the acquisition of 40 mm thick volumes, is ideal in patients with a heart rate (HR) at or lower than 65 beats per minute (BpM).

Every week, the Bichat Hospital (paris) sees its share of patients with heart and aortic disease. To further address both this growing incidence of cardiovascular disease and concern about dose reduction, the hospital upgraded its lightSpeed® vcT scanner to a lightSpeed VCT XT configuration. one of the key features of the lightSpeed VCT XT is GE Healthcare’s SnapShot™ pulse, a prospective ECG-gated CT acquisition.

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After conducting an accommodation and suitability study, we decided to use this low dose acquisition mode for aorta, iliac, and femoral angiography. The results were a drastic dose reduction and an improvement of image quality in regions subject to heart rate motions.

over the last five months, we have used this sequence to image 32 patients with the following conditions: an aortic dissection (type A and B); aortic valve stenosis requiring vascular cartography before aortic valve stenting with mechanical valve; and, thoraco-abdominal aneurismal pathology. This acquisition mode can be performed on a wide array of patients.

Clinical case

Helical Protocol (Patient A) versus SnapShot™ Pulse Protocol (Patient B)

Patient A

62-year old man presents with a suspicion of aortitis (Figure 1).

Acquisition protocolScanner ................................................................................................................lightSpeed® vcT XT*

Scan type ..........................................................................................................................................Helical

Gantry rotation speed ................................................................................................................0.6 sec

pitch .......................................................................................................................................................0.984

Detector configuration ............................................................................................. 64 x 0.625 mm

Slice thickness ......................................................................................................................... 0.625 mm

kVp ..............................................................................................................................................................120

mA ...............................................................................................................................................Modulated

Coverage ..................................................................................................................................... 55.25 cm

Contrast protocolContrast ........................................................................................... Iodinated contrast 350 mg/ml

Contrast injection rate ............................................................................................................3 cc/sec

Total contrast amount .................................................................................................................. 90 cc

Saline flush ......................................................................................................................40 cc, 3 cc/sec

DoseDlp ................................................................................................................................ 1203.05 mGy-cm

cTDivol .........................................................................................................................................20.09 mGy

Effective dose ....................................................................................................................... 18.04 mSv†

Clinical findings

The CT exam revealed mediastinal adenopathy, thickening of the aortic wall and infiltration of the mediastinal fat, all compatible with an aortitis and mediastinitis (Figures 2 and 3). Figure 3

Figure 2

Figure 1

*A premium lightSpeed VCT configuration. † obtained by EuR-16262 En, using an abdominal factor of 0.015 * Dlp.

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Patient B

56 year-old woman with aortic valve stenosis receives aorto-iliac cartography before endovascular treatment (Figure 4).


Scanner ................................................................................................................lightSpeed® vcT XT*

Scan type .................................................................................................................... SnapShot™ Pulse

Gantry rotation speed ............................................................................................................. 0.35 sec

Detector configuration ............................................................................................. 64 x 0.625 mm

Slice thickness ......................................................................................................................... 0.625 mm

kVp ..............................................................................................................................................................120

ma ..............................................................................................................................................................600

Coverage ............................................................................................................................................56 cm

Contrast protocol

contrast ........................................................................................... Iodinated contrast 350 mg/ml

contrast injection rate ............................................................................................................3 cc/sec

Total contrast amount .................................................................................................................. 90 cc

Saline flush ......................................................................................................................40 cc, 3 cc/sec

Dose

Dlp ...................................................................................................................................721.91 mGy-cm

cTDivol .........................................................................................................................................12.89 mGy

effective dose ....................................................................................................................... 10.82 mSv†

Figure 4

Jean-pierre laissy, MD, is a full professor in cardiovascular and interventional radiology and is a staff radiologist at Hospital Bichat (paris 18ème).

Gregoire Avignon received an engineering degree from Mines de nancy school in 2007 and a marketing master degree from HEC (High Commercial Studies), paris. He began working for GE Healthcare in September 2007.

Jean-Michel Serfaty, MD, is an assistant professor in cardiovascular and interventional radiology and is a staff radiologist at Hospital Bichat (paris 18ème).

About the facility

The Hospital Bichat is one of 37 hospitals within the ApHp (public Assistance – paris Hospital). With 956 beds, the hospital has a dual mission: to ensure a proximal location for healthcare throughout the north paris population and to deliver high-quality, specialized patient care in six fields – vascular pathology and cardiology, emergency resuscitation, lung pathology, specialized medicine, surgery, and tropical diseases.


† obtained by EuR-16262 En, using an abdominal factor of 0.015 * Dlp.

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Figure 7

Figure 6

Figure 5

Figure 8

Figure 9. Radiation dose comparison.

Helical Protocol

SnapShot Pulse Protocol

Percent Reduction

Dose Length Product (DLP)

1203.05 mGy-cm 721.91 mGy-cm 40.0%

CTDIvol 20.09 mGy 12.89 mGy

Z-Axis Coverage 55.25 cm 56 cm

mA variable 600

kVp 120 120

Clinical findings

Figure 5 shows the ascending aorta, aortic valve, and aortic annulus (where the valve prosthesis will be implanted), and origin of the left coronary artery (which shows no atherosclerotic infiltration), with no artifact related to the sequential acquisition mode.

Figure 6 (VR thoracic reconstruction), Figure 7 (curved reconstruction), and Figure 8 (flat reconstruction for measurement of aorta, iliac, and femoral artery diameters) display a mild tortuosity of the right iliac artery with a minimum diameter of 8 mm in the common femoral artery, providing the required clinical data to authorize the endovascular heart valve prosthesis implantation procedure.

Discussion

The benefits of the lightSpeed® vcT XT* configuration with the SnapShot™ pulse prospectively ECG-gated imaging technique are apparent with these clinical cases. The technique demonstrated a 40% reduction in radiation dose for the same Z-axis coverage as the helical technique.

Among the 32 patients included in this study, we obtained lower doses using 100 kVp with either the helical or the SnapShot pulse protocol, with excellent image quality as well.

We therefore recommend the use of the SnapShot pulse prospectively gated imaging technique when exploration of the full aorta, iliac, and femoral artery is needed. n


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© 2009 General Electric Company, doing business as GE Healthcare.

Introducing the GE Discovery™ CT750 HD.

Sometimes repetition is a good thing. Like when it means reliability, quality and consistency. The Discovery CT750 HD thrives on dependable, repeatable outcomes. It features a new Xtream™ HD console that combines the familiar Xtream interface with the power to meet increasingly demanding clinical challenges. And the system’s industry-exclusive Gemstone™ detector provides more clarity than ever before, ensuring more consistency from exam to exam. It all adds up to unsurpassed quality and reliable results. Again. And again. And again. CT Re-imagined.

To witness the leading edge of CT clarity, visit www.gehealthcare.com/CT750, or call 866-281-7545 and reference CT Clarity – Spring.

Repeatable results.

GE Healthcare

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t e c h n i c a l i n n o v a t i o n


D i S C o v E r y C T 7 5 0 H D

a Moment in timeBy Gene Saragnese, Vice President and General Manager, Computed Tomography

Throughout medical history, there are certain moments in time when the world changes. in the world of computed tomography (CT), those moments in time include the invention of the solid state detector to improve image clarity while lowering dose, as well as multi-slice CT for enhanced resolution.

yet sometimes we don’t realize when we are in a ‘moment in time’ until after it is gone. if you realize it while it is happening, that is a time to savor and appreciate the event that is reshaping not only your world but others around you as well.

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a Moment in timeGene Saragnese, vice President and General Manager, Computed Tomography, GE Healthcare

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We also believed that there was more information to glean from CT imaging, either through dual energy or spectral imaging. So the prospect we brought forth into our research and development was to enable our customers with the ability to see more with better image quality, know more by extracting new information from CT images, and do all of this with less dose.

With this foundation in place, we examined the underlying technology and set a very specific course. A linear extension of existing technology was not the answer. our belief, which holds true today, is that only by reinventing every aspect of the imaging chain could our customers reap the benefit of improved image clarity with lower dose.

This has meant making some calculated research and investment decisions. With the strength of GE’s Global research Center behind us, we had the capability to implement fundamental changes into imaging. For example, element by element, we examined the periodic table so we could determine which could offer the greatest advancement in a new scintillator material. This effort culminates in the Gemstone™ detector, the first new detector material for computed tomography in 20 years.

This investment is beginning to pay off. We have developed new reconstruction technology, a data acquisition system, and a new X-ray generator that, together with the Gemstone detector, is opening new imaging capabilities – a game changer that provides higher resolution, lower dose, and artifact suppression while enabling the synthesis of monochromatic images and dual energy material decomposition.

The result is the most research-rich CT that the industry has ever seen – the Discovery™ CT750 HD. on the following pages, you will learn more about the extraordinary components that together lay the foundation for the future of computed tomography.

This is a moment in time for CT imaging. n

The prospect we brought forth into our research and development was to enable our customers with the ability to see more with better image quality, know more by extracting new information from CT images, and do all of this with less dose.

– Gene Saragnese

Today at GE Healthcare, the Discovery™ CT750 HD launch is one of these ‘moments in time.’ The culmination of this 10-year process is more than just working toward the launch of a new product. This is the zenith of a vision set a long time ago. A vision not focused on delivering more slices or tubes, but rather based on the belief that the foundations and technologies of CT should be challenged and re-imagined. a course that embodies a vision that departs from standard convention to one that delivers what our customers say they need.

in the beginning, we set forth on a course to create a CT scanner that delivers higher spatial resolution, greater image clarity, and low contrast detectability, all with less dose. We knew it would not be easy. To achieve success, we had to advance multiple fronts; redesign of the digital acquisition system (DAS), a new X-ray tube, and a new scintillator material, all requiring incredible foresight. As a result of this enormous effort, we believe the world of CT imaging is in a different place.

This journey began with our customers, who said unequivocally that their number one requirement is image quality and image clarity. Physicians are making life and death decisions based on image interpretation; improving the quality of that image means improving the quality of their patients’ lives.

our customers also told us they want a highly reliable, multi-purpose application scanner, one that does not just fill a certain niche, but a scanner that serves multiple clinical needs.

As we examined improving image quality, we knew that radiation dose would play a fundamental role. intuitively, in order to improve image quality, you must increase radiation dose. yet a long-standing principle here at GE has been to drive dose lower. How could we bend this physical law and allow our customers to see more and to know more with less dose? The key was to re-engineer the imaging chain for image clarity while creating algorithms for reconstructing low mA images.

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t e c h n i c a l i n n o v a t i o nD i S C o v E r y C T 7 5 0 H D

CT Sampling Technology

one of the most important, and often overlooked, design aspects of a CT scanner is the sampling technology used to generate data for the reconstruction of an image. The sampling design is an example of true system design as it leverages and integrates multiple technologies (Data Acquisition System or DAS, tube, and detector) to create an image, and in the case of the Discovery™ CT750 HD scanner, a true high definition, high resolution image.

By Naveen Chandra, Lead CT System Architect

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Key concept: views per rotation

Before exploring the sampling design in some detail, it is useful to review one of the key sampling concepts, the term “views per rotation” (vPr). vPr refers to the number of samples taken (or number of integrated samples taken in the case of most DAS systems) with every rotation of the gantry, for use in the reconstruction of the image.

This term is often confused with the term “samples per second” (samples/sec), which is similar but not as applicable to a CT system as it does not directly convey the actual number of samples used to make an image. in most cases the samples/sec number will appear to be higher, but actually translates into less information being used to reconstruct an image, and as a result, translates into less resolution for the scanner.

To make this more clear, let’s look at how one would compare a CT system “A” with a DAS that is capable of 2496 vPr at a 0.35 sec rotation speed, with a CT system “B” that has a DAS capable of 4640 samples/sec at the same 0.35 sec rotation speed.

System “A” 2496 vPr @ 0.35 sec = 1 sample every 140 microseconds = 7131 samples/sec

System “B” 4640 samples/sec @ 0.35 sec = 1 sample every 216 microseconds = 1624 vPr

Clearly System “A” has a distinct advantage as it is actually using more views of the object for every rotation in order to reconstruct an image. Essentially you want to take a certain number of snapshots per rotation, in order to get equivalent sampling resolution, which is a contributing factor to image quality (iQ) at all gantry rotation speeds. Having a fixed samples/sec DAS implies that you take less snapshots at faster speeds, delivering sub-optimal iQ. A fixed vPr DAS implies that you take the same number of snapshots at all speeds, thereby conserving the resolution at your fastest speeds.

As can be seen from the calculations above, the number of views per rotation is actually a better, more objective gauge of a CT system’s capability because it actually frames how the DAS capability is used to make an image.

Volara™ HD DAS

Performix® HD tube

Gemstone™ detector

Figure 1. CT sampling technology triangle

Naveen Chandra, Lead CT System Architect, Ge healthcare

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The CT sampling technology triangle

Designing a CT scanner for high spatial resolution means evaluating the components that drive image acquisition – the data acquisition system, the X-ray tube, and the detector. These three critical components form the sampling technology triangle (Figure 1), and a good system must leverage all of these components in order to obtain higher resolution and better image quality. This goal can only be reached by designing, integrating, and leveraging the capabilities of all of these components.

the volara™ HD DAS is the first corner of the sampling triangle, and has the capability to sample every 136 microseconds, which is used to deliver 2496 vPr for all rotation speeds in high resolution imaging mode. This is a key breakthrough in DAS sampling technology, and allows for sampling uniformity across all rotation speeds. By sampling this quickly, it allows for a reduction in the uncertainty of the position of an object (or in other words brings higher resolution).

Taking less views per rotation increases the spatial uncertainty, which results in a lower precision of the object location (or in reality resulting in lower resolution). Essentially, by sampling more densely, one is able to determine more precisely the location of an object or an edge that is imaged. it is important to note resolution naturally degrades as you move away from iso-center (iSo). Taking more views per rota-tion drastically reduces the uncertainty away from iSo, trans-lating into a full field-of-view (Fov) improvement in resolution. A clear example of this benefit can be seen in Figure 2, where the same phantom is imaged at approximately 20 cm from iSo with two different sampling schemes.

The second corner of the technology triangle is the X-ray tube. The new Performix® HD tube, developed specifically for high resolution imaging, improves resolution by allowing additional view sampling without increasing the required X-ray output. This is accomplished by dynamically deflecting the focal spot, enabling the ability to see more.

The primary goal of a high resolution scanner is to increase the spatial resolution in order to bring better clarity to the images. one of the ways to do this is to change the sampling pattern to enable multiple looks at the same object while gaining addition-al information and not increasing dose. This is accomplished through the X-ray tube by deflecting the focal spot. Essentially, with the ability to slightly deflect the position of the spot in-plane, one is able to obtain informa-tion about the same object across multiple cells at different view angles. This allows us to determine more about the object’s precise location and deliver higher resolution. Another way to look at this is that one gets additional distinct samples at differ-ent view angles per detector cell, thereby increasing the amount of information used in the reconstruction of the image.

The astute reader may notice on top of the technological chal-lenges of taking more views per rotation there is also a flux tradeoff. in order to take more views, one needs to spend less time integrating at each view, which results in less signal per view. Having a 100 kW tube and a noise reducing reconstruction algorithm like ASir (which provides equivalent noise with up to 50% less dose) in the arsenal makes taking advantage of high resolution sampling easy.

The third corner of the technology triangle is the Gemstone™ detector. The extremely fast speed of this detector enables the Discovery™ CT750 HD to take full advantage of the faster sam-pling of the DAS and the dynamic focal spot deflection capability of the X-ray tube, thus significantly improving the spatial resolution. Some of the key features of this new detector technology that allow it to be used for optimal sampling are the fast decay time (primary speed) and its distinct lack of afterglow. Both of these effects have traditionally challenged the optimiza-tion of proper sampling in CT systems, and with the advent of this new technology, fast sampling complications are a thing of the past.

Afterglow refers to a secondary decay of light emitting from the scintillator for several milliseconds after the X-ray source is

Figure 2. improvement in resolution due to increased sampling. Approximately 20 cm from iSo-center.

Standard sampling Increased sampling

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turned off. it carries a part of the signal from one view to the next during a scan, thereby smearing the information and potentially causing artifacts extending from low attenuation anatomy into areas of higher attenuation. This has the direct effect of decreasing in-plane spatial resolution.

The Gemstone™ detector has a primary decay time of only 30 nanoseconds, making it 100 times faster than GoS and crowning it as the fastest scintillator in the CT industry. it also has afterglow levels that reach only 25% of GoS levels,1 making it ideal for fast sampling and high resolution.

Clinical benefits

Some of the most prevalent benefits of an optimized sampling design are a reduction in azimuthal blurring, a reduction in aliasing artifact, an increase in resolution across the entire Fov, and improved in-plane resolution. For the Discovery™ CT750 HD this comes in the form of an MTF 50% increase of 3 lp/cm and an MTF 10% increase of 4.5 lp/cm over LightSpeed® vct.2,3 However, the real measure of performance comes in the form of clinical imaging benefits.

An example of artifact reduction can be seen in Figure 3, where the improved view sampling has led to an increased ability to distinguish higher resolution anatomy, rendering a more useful clinical image.

in addition, higher resolution actually means that you can see more in an image. Figures 4 and 5 show clear, practical examples of some of these gains. in this instance, the benefits of improved sampling come in the form of increased airway visualization, even at an extended Fov.

The trio of advanced technologies – DAS, X-ray tube, and detector – all relate back to what is known as the CT sampling design. By working the development of these key CT system technologies in concert, one can truly achieve an optimal design delivering high resolution with true clinical benefits. n

References

[1] JS vartuli, rJ Lyons, CJ vess, KP McEvoy, rS Hagerdon, SJ Duclos, M Nayak, and H Jiang, “GE Healthcare’s New Computed Tomography Scintillator – Gemstone.” presented at 2008 Symposium on radiation Measurement and Applications, June 2-5, 2008, Berkeley, California.

[2] LightSpeed vCT Datasheet

[3] Discovery CT750 HD Datasheet

Improved view sampling

Figure 3. Artifact reduction as a result of improved sampling.

Conventional sampling

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info about clinic, etc.



Conventional sampling Improved view sampling

Figure 4. increased airway visualization at extended Fov as a result of improved sampling.

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Conventional sampling

Figure 5. increased airway visualization as a result of improved sampling.

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Solving the High Image Quality with

low Radiation Dose Paradox

L o w - D o S E R E C o n S T R u C T I o n – A S I R

what is the primary concern that physicians have regarding the use of CT systems versus other modalities? Dose.

Across the world, there is a general clinical consensus to lower the patient’s exposure to radiation dose, particularly during CT scanning. Yet, reducing the dose on existing CT systems often had a negative impact on image quality.

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L o w - D o S E R E C o n S T R u C T i o n – A S i R


Figure 1a. non-hDct Figure 1b. Discovery CT750 HD

with the introduction of the Discovery™ CT750 HD and the LightSpeed® VCT XTe,* GE Healthcare provides a new opportunity for clinicians to significantly reduce dose without affecting image quality. A new reconstruction technique, Adaptive Statistical iterative Reconstruction (ASiR), enables reduction in image noise and improvement in low contrast detectability (LCD) and image quality.

By reducing the image noise in CT images, ASiR decreases dose across the entire body by up to 50% for Discovery CT750 HD, and up to 40% for LightSpeed VCT XTe,* allowing you to manage dose without sacrificing image quality. The Discovery CT750 HD scanner also delivers up to 40% improvement in LCD and improves the image quality at 50% lower dose.

The R&D path to lower dose began nearly eight years ago. As GE grappled with the issue of how to lower dose, GE engineers, scientists, and external research partners examined different approaches to image reconstruction. According to Jiang Hsieh, Chief Scientist, GE Healthcare, they discovered that the model-based iterative reconstruction (MBiR) algorithm approach showed great promise by significantly increasing image quality, but it took too long for practical clinical use.

“we all knew that we were onto something important,” says Hsieh, “so we began to evaluate how we can obtain the benefits of ASiR while simultaneously reducing the time element.” As Hsieh and his peers examined the algorithm, they determined the greatest amount of time was consumed during modeling of the system optics. Therefore, they focused their efforts on the statistical portion of the algorithm.

The result is ASiR: a new algorithm that decreases reconstruction time and reduces image noise for the cumulative effect of improving image quality.

ASiR doesn’t stop there. “By reducing noise, ASiR enables clinicians to also reduce tube current (mA) without impacting image quality,” adds Hsieh. “The crux of our design philosophy surrounding ASiR was to reduce noise, decrease the reconstruction time, and lower the dose – and accomplish this with greater image clarity.”

These comparison images above (Figures 1a and 1b) are from the same patient scanned at different mA values, 251 and 161 respectively. All other scan parameters were the same. The Discovery CT750 HD image at 161 mA delivers the same noise measurement in standard deviations as the non-HDCT image. This is a dose saving of approximately 36%.

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L o w - D o S E R E C o n S T R u C T i o n – A S i R

Figure 2a. CT750 HD without ASiR Figure 2b. CT750 HD with 50% ASiR

Figure 3a. CT750 HD without ASiR Figure 3b. CT750 HD with 50% ASiR

The images in Figure 2 are both from the same HDCT data set. The image on the left does not have ASiR applied. The image on the right was reconstructed using 50% ASiR.

This last image set (Figure 3) demonstrates the application of 50% ASiR; note that there is no loss in anatomical detail and the anatomical integrity of the image is maintained.

in summary, ASiR is an advanced reconstruction algorithm that, when used in combination with a lower mA, can deliver up to 50% less dose to the patient on the Discovery™ CT750 HD and up to 40% less dose to the patient on the LightSpeed® VCT XTe,* yet still maintain equivalent image quality without a loss in spatial resolution or anatomical integrity. n


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This is no different in radiology. Image quality drives a radiologist’s ability to see anatomy or pathology and quantify it with accuracy. Our customers tell us image quality is the single most important aspect of CT imaging, which is why GE Healthcare places so much emphasis in this area.

Parallel to image quality is the responsibility to lower dose. No one disputes that the efforts to lower dose is the proper action to take with ever-increasing healthcare demand for imaging in order to make a definitive diagnosis.

At GE Healthcare, we also believe that gaining insights into the way the body functions is central to understanding disease and personalizing treatment for the individual.

Together, these three central themes are the embodiment of the new Discovery™ CT750 HD and what we mean by See More, Know More, Less Dose.

The overall image quality of a CT image is divided into four core components. Each component contributes to the visual appearance of the image and can greatly impact the quality of the diagnosis:

Spatial resolution – the degree of blurring in an image;•

Low contrast detectability – the ability to differentiate between adjacent • tissue densities;

Noise – interference or the uniformity of CT number inaccuracies; and,•

Artifacts – distortion in the image that is unrelated to the subject • being studied.

Re-inventing the CT Imaging ChainBy Bob Beckett, CT Global Product Manager

Image quality is central to so many facets of our life. As consumers, we demand it, whether it is for HDTV, eyeglasses, video games, or a computer screen. Seeing things clearly with true representation is always preferred – intuitively, there is value in image quality.

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Bob Beckett, CT Global Product Manager, Ge healthcare


During the development of the Discovery™ CT750 HD, we utilized these four core components of image quality, observing differing tissue densities while reducing noise and artifact. This overhaul was going to take more than an extra X-ray tube or more detector rows. This required re-inventing virtually the entire imaging chain.

Each CT subsystem has an impact on the scanner’s ability to generate the highest level of image quality with the lowest possible dose. Yet it isn’t just about improving each aspect of the scanner, rather it is improving each in unison so all components work in harmony together.

We knew the future CT system would require a new scintillator, one that would enable higher sampling rates, particularly for dual energy, to contribute to higher image quality. The re-designed Data Acquisition System (DAS), which manages the amount the information in the reconstruction process, harvests more views to create an image. A new X-ray tube was also necessary, one that would switch between two energy levels. We also included dynamic focal spot control and higher mA focal spots for better image quality in larger-sized patients. And last, a new Adaptive Statistical Iterative Reconstruction (ASIR) algorithm to increase low contrast detectability up to 40%, in order to suppress artifact, contributes to dose reduction by up to 50%.

The result is high-definition, high-resolution CT imaging across all anatomic areas and clinical applications with significantly lower dose. In fact, the Discovery CT750 HD delivers 230 microns of resolution for scanning modes of up to two meters in scan range for true head-to-toe coverage. Historically, CT systems have achieved this level of resolution only for specific anatomic regions, and only with higher dose levels.

The clinical possibilities of the new Discovery CT750 HD are truly exciting, including the ability to:

See small vessels from the proximal to distal extremes; •

Accurately quantify stenosis in coronary and vascular vessels;•

Minimize distortion and artifacts;•

Quantify, measure, and analyze suspicious pathologies • and lesions, wherever located within the body;

Segment and isolate pathology for treatment planning; and,•

Offer high quality diagnostic imaging using up to 50% less dose.•

Higher image quality translates to greater levels of clinical precision and confidence. And lower dose is simply the responsible approach to the future of CT imaging.

Hardware and software has a life span. At some point in time, a new platform must take root to enable the user to leap into the next generation of technology. The Discovery CT750 HD is that new platform that will take our customers well into the future. n

Both images were generated from the same CT raw data. The top image is a typical reconstructed image using low dose technique at 87 mAs. The bottom image is reconstructed using the HD advanced reconstruction algorithm (ASIR). Notice the kidney stone clarity in the left kidney.

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P e D i a t R i c i M a G i n G

Ge takes leadership Role in Pediatric CT Imaging

Ge healthcare has taken a leadership role to reduce ct radiation dose to all patients by embracing the ALARA (As Low As Reason-ably achievable) principle. For pediatrics, this includes assisting in the development of the Color Coding for Kids protocols in 2001 (see “color-coded ct Protocols help Reduce Dose for Pediatrics,” CT Clarity Fall 2007, pg. 54-55; available at www.gehealthcare.com).

GE’s long-term roadmap for pediatric CT scanning is centered on dose reduction and efficiency.

This includes introducing new features that will make the LightSpeed® and BrightSpeed® series

more applicable for dedicated pediatric scanning in children’s hospitals across the nation. children born

today have a higher probability of receiving a CT scan. The likelihood of this occurring more than once is greater

in their adult years. Therefore, GE believes it is essential and

The FDA recommends that facilities evaluate CT operating conditions to ensure an optimum

balance between image quality and radiation exposure. This includes determining the

proper dose based on patient weight or diameter and anatomic region

of interest.

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Mannudeep K. Kalra, MD is the director of the Center for CT Dose Optimization, Support and education at Massachusetts General hospital and a clinical fellow in Divisions of cardiac and Thoracic Imaging. His key research areas include CT radiation dose, image post processing and radiology informatics. In the past six years, Dr. Kalra has published several dozen scientific papers and reviews on ct radiation dose reduction in major radiology journals.

Sarabjeet Singh is a clinical research fellow in the Department of Radiology at Massachusetts General hospital. he received his Bachelors of Medicine & Surgery (MBBS) from G.G.S. Medical College & Hospital (Punjab, India) and a Masters in Medical Sciences & Technology (MMST) at Indian Institute of Technology (Kharagpur, India). His research interests include CT radiation dose optimization and clinical aspects of technological advances in CT imaging.

responsible to continue developing technology that enables a reduction in dose with all exams. Over time, the entire patient population will benefit as dose-lowering techniques and applications migrate into virtually all types of CT studies.

With children, it is particularly important to minimize the time spent in the scanner to reduce the chance for movement. this requires fast acquisition speeds as well as higher spatial resolution to image smaller anatomy. GE believes this challenge will benefit all patients who receive ct scans.

GE’s dedication to reducing dose in pediatric CT imaging studies is coming to fruition through product innovation and education. Our commitment began with pediatric protocols loaded onto the scanner and continues through the development of features on our Discovery™ CT750 HD system that will benefit the pediatric population. We have developed educational training courses to help clinicians better utilize dose reduction techniques, particularly in institutions that do not routinely scan children, and continue to support both clinicians who develop dose-lowering techniques and the medical societies that strive to create awareness through education.

Pediatric protocols to reduce dose

Ge healthcare has developed specific procedure-based protocols to reduce dose that take into account the patient’s weight, clinical indication, and number of prior CT studies, and all use Z-axis tracking with Auto mA. Three color zones comprise the Ge protocols.

“With three procedure-based zones, radiologists can manage levels of radiation dose in an efficient and seamless manner based on clinical need, index or follow-up CT, and the target region of interest,” says Mannudeep K. Kalra, MD, director of the Center for CT Dose Optimization, Support and Education at Massachusetts General Hospital. Within each zone, Auto mA is used according to five weight categories.

“Prior publications have shown that adjusting scanning protocols to patient size or weight, particularly for children, is an efficient method for reducing radiation dose while maintaining diagnostic quality,” he adds. “Published literature also shows that mA and kVp are the most frequently adapted techniques for optimizing radiation dose to patient size.”

Dr. Kalra points out that automatic exposure control techniques such as auto ma and Auto mA 3D can perform the task to reduce radiation automatically.

Ensuring high image quality is critical to these dose reducing protocols. “Image quality is taken into account when choosing the proper zone,” says Sarabjeet Singh, clinical research fellow in the Department of Radiology at Massachusetts General Hospital. “For example, a zone with higher mA levels is used for more subtle lesions, whereas images taken for a calcified stone or bone segment are taken in a lower mA level.” Other dose reduction strategies used were smoother kernel, thicker slices (5 mm), low kVp, and higher pitch.

Upon further examination of pediatric ct studies conducted on the same patient before and after implementation of procedure-based protocols, Singh and Dr. Kalra found that while dose can be reduced, non-compliance in using the protocols consistently is an issue. “Slightly over 50% of chest CT and nearly 75% of abdominal

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CT studies were performed according to the procedure-based protocols,” states Dr. Kalra. “When compared to studies performed without full compliance, radiation dose for chest and abdominal CT studies was reduced.” In patients weighing more than 100 lbs., Singh and Dr. Kalra found an even greater dose reduction.

The key to dose reduction using the procedure-based protocols is consistent use. “Promoting awareness and the rationale for using these protocols was a big part of our ability to significantly reduce dose,” says Dr. Kalra. “Lowering dose with these protocols starts with the radiologist and technologists selecting the appropriate color and weight zones.”

“Posters were put up in all ct suites and in the pediatric interpretation area. This approach helped to drive compliance in using the new protocols,” adds Singh. n

Patient 1

Five-week male infant follow-up study was performed using the GREEN zone protocol.

Acquisition protocol/dose parameters

kvp ....................................................................................................................80

noise index ..................................................................................................7.0

ma ................................................................................................................. 100

Rotation speed ...................................................................................0.5 sec

Scan coverage ................................................................................145 mm

DlP .........................................................................................80.06 mGy-cm

Phantom type ..........................................................................Head 16 cm

ctDivol ............................................................................................... 4.64 mGy

Effective dose ................................................................................ 2.4 mSv*

* Obtained by ICRP newborn abdomen factor of 0.049 * DLP. Reference: Annals of the ICRP, Volume 37, Issue 1, March 2007.

Patient 1

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By XXXXXX XXXXXXX X XX XXXXX XXXXXXXXXXXX



Patient 2

Patient 2

17-month male infant with massive abdominal tumor; CT angiography, using the GREY zone protocol, was used to evaluate the abdominal vessel conditions.

Acquisition protocol/dose parameters

kvp ................................................................................................................. 100

ma ...................................................................... AutomA, range 136-157

noise index ..................................................................................................7.0

Scan coverage ................................................................................355 mm

DlP ...................................................................................... 383.57 mGy-cm

Phantom type ..........................................................................Head 16 cm

ctDivol ............................................................................................... 9.93 mGy

effective dose ...........................................................................11.50 mSv*

* Obtained by ICRP 1-year old abdomen factor of 0.030 * DLP. Reference: Annals of the ICRP, Volume 37, Issue 1, March 2007.

“ With three procedure-based zones, radiologists can manage levels of radiation dose in an efficient and seamless manner based on clinical indication for CT, index or follow-up CT, and the target region of interest.”

– Dr. Mannudeep K. Kalra

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In the October 2006 issue of Diagnostic Imaging, I wrote a brief article describing the benefits of using prospective gating axial (PGA) when performing coronary CT angiography.1 Since then a number of software and technique improvements have occurred which make possible the use of PGA in the everyday clinical setting. In our practice, prospective gating is used in 98% of our coronary CTA patients as the initial and only scan technique. It has become rare for us to default initially to retrospective gating or reinject a patient to do retrospective gated helical (RGH) CCTA because of a failed prospective gated acquisition.

By David A. Dowe, MD, Medical Director, Coronary CTA Program, Atlantic Medical Imaging

State-of-the-art coronary CTA now possible with radiation comparable to a calcium score.

Ultra-low Radiation Dose, Prospectively Gated Coronary CT Angiography

Copyright 2008 by Bryn Mawr Communications II LLC. Reprinted with Permission from Cardiac Interventions Today, April 2008 issue. Portions of this article have been modified with permission from the author and Cardiac Interventions Today.

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b e y o n D t h e s c a n


s n a p s h o t p u l s e

David a. Dowe, MD, is medical director and coronary CTA Program director, Atlantic Medical Imaging (Galloway, New Jersey). He received his medical degree and completed his residency at SUNY Health Science Center (Syracuse, New York). Dr. Dowe is board-certified in diagnostic radiology by the American Board of Radiology; special interests include coronary cta and nuclear medicine.

Dr. Dowe lectures nationally and internationally, has written several articles related to coronary cta and collaborates on coronary research and development.

About the facility

Atlantic Medical Imaging (AMI) is a full service, outpatient imaging practice operating seven offices throughout New Jersey and providing professional services to three area hospitals. Since 1964, AMI’s goal has been to provide the most advanced diagnostic imaging services to our patients and referring physicians. With 32 board-certified, sub-specialty trained radiologists and a staff of 350 technical, clerical and administrative personnel, aMI is committed to providing patients with unsurpassed service and care and will ensure that their visit is comfortable and relaxing. AMI offers a full spectrum of diagnostic imaging services including CT, Coronary CTA, MRI, Nuclear Medicine, PET/CT, Digital Mammography, Ultrasound, DEXA, General Radiology and Fluoroscopy, and Interventional Radiology.

AMI was one of the first diagnostic imaging centers in the country to install GE’s 64-slice LightSpeed® VCT scanner, the most technologically advanced ct scanner available on the market today. The 64-slice CT scanner can produce extremely high-quality images at sub millimeter resolution in only a few seconds. Since 2001, Atlantic Medical Imaging has been performing Coronary CT Angiography (CTA) and has performed more than 10,000 exams to date.

This article will briefly describe the prospective gating acquisition protocol. I will then present the ultra-low radiation exposure CCTA technique that results in radiation exposure comparable to that of a coronary artery calcium (CAC) score and compare the radiation exposure from cardiac imaging studies as they relate to CCTA.

Basics of prospective-gated coronary CTA

Prior to PGA, the most effective radiation dose reduction technique was EKG dose modulation. EKG dose modulation is used when performing RGH. It reduces dose by decreasing the millamperage (mA) of the X-ray beam in the systolic and near-systolic portions of the cardiac cycle where one is unlikely to be using the data to post-process the coronary arteries (Figure 1). This results in approximately 30% reduction in radiation exposure. What prevents this technique from reducing radiation dose further is that the X-ray beam remains on throughout the cardiac cycle even when no images will be reconstructed during the reduced exposure. This results in unnecessary radiation dose being delivered to the patient, which is inherent in all helical-acquired CCTA exams (Figure 2).

Figure 1. EKG dose modulation limits radiation exposure my decreasing the mA during the portions of the cardiac cycle where you will not be reconstructing the coronary arteries. EKG dose modulation decreases radiation exposure by 30%.

Figure 2. Although one routinely uses EKG dose modulation with Retrospective gated CCTA the X-ray beam is on throughout the cardiac cycle resulting in increased radiation exposure.

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b E y o n d T H E S C A nS n A p S H o T p u l S E

pGA avoids this extraneous radiation dose by completely turning off the X-ray beam during most of the cardiac cycle (Figure 3). The portion of the cardiac cycle that is to be radiated is selected before the scan, hence the term “prospective.” The radiated window (duration of the tube turned on) may be left wide, which makes it possible to reconstruct vessels across a range of cardiac phases. This comes at the expense of increasing radiation dose. before the scan, the user must select the phase of the cardiac cycle in which the reconstruction will be centered. I routinely use the 75% phase, which in patients with heart rates <65 bpm places this within diastole. In the pGA protocol, there is a default time added to the window for the tube on-time (dynamic padding) based on the patient’s heart rate. However, if the patient’s heart rate is <65 bpm one can conclude that the post-processing will be successful, i.e., diagnostic images of all 15 American Heart Association (AHA) coronary artery segments, with the single 75% phase for reconstruction. For this reason, I always override the default padding and manually enter a 10 msec padding surrounding the 75% phase (Figure 4). As an example, in a patient with a heart rate of 60 bpm, the duration of the cardiac cycle is 1,000 msec. by radiating only 10 msec before and after the 75% phase, you only radiate 2% of the cardiac cycle, in addition to the window centered at the 75% phase (Figure 1). using pGA with the default padding reduces radiation by 52% to 74% when compared to RGH with no loss of image quality (Figures 5 to 7).

Figure 3. With pGA the X-ray beam is either on or off resulting in substantially decreased radiation dose. A prerequisite is having a heart rate <65 bpm.

Figure 4. The CT scanner will set the radiation padding length on either side of the 75% window based on the heart rate. I routinely override this function and use a 10 msec pad.

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b e y o n d t h e s c a n



Figure 6. Images A and C are prospectively gated and B and D are retrospectively gated. The images are indistinguishable with 70% dose savings.

a

a

b

b

c d

Figure 5. Retrospectively gated (A) and prospectively gated (B) images on the same patient. There is no loss in image quality or diagnostic accuracy with 70% dose reduction.

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Figure 7. Indistinguishable curved MPR images with prospectively gated (A) and retrospective gated (B) on the same patient.

Figure 8. A 38% dose reduction results by reducing the kVp from 120 to 100.

a b

When manually decreasing the padding to 10 msec, the radiation exposure can be reduced by up to 83%. This dramatic reduction in radiation exposure easily justifies administering beta-blockers in order to decrease the heart rate to 65 bpm or less. PGA may, in fact, be used in patients with heart rates between 65 and 70 bpm but it is somewhat less consistent in obtaining all 15 AHA coronary artery segments at post-processing. A drawback of PGA is that functional evaluation of the heart is not possible since images are not collected at all phases of the cardiac cycle.

Ultra-low dose, 100 kVp, prospective gated CCTA

before one can consider the topics of spatial and temporal resolution as they pertain to CCTA, you must be able to obtain images with an adequate signal-to-noise ratio (SNR) in order to visualize the coronary arteries. The demands for an increased snR are most apparent in the obese and morbidly obese patients. In these patients the use of 650 to 800 mA may be necessary to obtain diagnostic images. In scanners whose maximum tube current is less than this, you may be forced to increase kVp to 140 kVp from the usual 120 kVp. Each incremental increase of 20 kVp results in a 38% increase in radiation exposure. Obviously, a reduction in 20 kVp decreases radiation exposure by 38% (Figure 8). It is important to titrate your technical factors to the minimum needed for adult patients of different body mass indices (BMI) and body habitus. BMI is the variable I use to select the kVp and ma for both pGa and RGh. out of the development of pGa has come the realization that image quality can be preserved in many patients by using 100 kVp instead of the 120 kVp I routinely used with RGH. Using 100 kVp results in ultra-low radiation dose CCTA. In many patients, the dose from this scan is comparable to coronary artery calcium score (Table 1).

Table 1. Window Padding Centered at 75%

At a heart rate of 60 bpm, the RR interval is 1000 msec in length.

Using the rate determined by computer padding, we would irradiate 200 msec of the RR interval or 20% in addition to the 75% phase.

Using the override padding, we would radiate only 20 msec of the RR interval or only 2% in addition to the 75% phase.

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Conclusion

PGA is now achievable in the overwhelming majority of patients needing CCTA. It requires a heart rate of <65 bpm, which is easily and safely obtained by the administration of beta-blockers. Given the massive reduction in radiation exposure, I feel that PGA should become the standard of care and will likely force the hand of all CT vendors to develop this capability. Given that PGA radiation is now on par with that of a calcium score, CCTA could quickly become the initial exam used in symptomatic patients suspected of having CAD. n

Figure 10A.

Quadruple rule-out examination. Curved multiplanar reformat (10A) and lumen view (10B).

Figure 10B.

References:1. Dowe D. Prospectively gated computed tomographic angiography dramatically reduces radiation

dose. Diagn Imaging 2006:28(suppl):1-5.

Figure 9A.

Quadruple rule-out examination. Arterial phase opacification of the carotid arteries, aorta, and coronary and pulmonary arteries. This acquisition was obtained with 5.8 mSv of radiation exposure. Curved MIP (A) and 3D volume rendered (B). Cardiac transparency image of a quadruple rule-out (C).

Figure 9B. Figure 9C.

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I m a g e g e n t ly c a m p a I g n

It is already late in the evening when a six year-old child is brought to the emergency room after a serious car accident. She’s awake and coherent but complaining about severe abdominal pain. The ED physician is greatly concerned about internal injuries or bleeding, and orders a CT scan to diagnose the patient’s condition.

Before the child is brought into the CT scanning room, the CT technologist pulls the patient chart, reviews her weight and size and, through the Color Coding for Kids feature on the GE Healthcare LightSpeed® VCT, selects the appropriate child-size CT scanning protocol. Thanks in large part to the Image gentlysm campaign from the Alliance for Radiation Safety in Pediatric Imaging, radiologists and technologists have become aware of the need to “child-size” adult protocols. As a result, technologists now know to access child-friendly protocols available on GE’s LightSpeed and BrightSpeed® ct scanners to help them deliver the appropriate “child-size” radiation dose to pediatric patients.

Image Gently

The Image Gently campaign is the result of a grassroots effort initiated by pediatric radiologists concerned about the use of adult CT protocols on children. According to Marilyn Goske, MD, Chair, Society for Pediatric Radiology (SPR) and Alliance Chair, “This initiative has come about because of the passion of many members and volunteers concerned about improving children’s health.”

Grassroots Campaign Creates Awareness for Lowering Pediatric Dose

The Alliance began as a subcommittee within SPR in 2006 and was almost immediately supported by an unrestricted educational grant from GE Healthcare. “I firmly believe that having the support and appropriate involvement of GE Healthcare early on helped us get started,” Dr. Goske says.

In early 2007, three other organizations joined the Alliance – the American College of Radiology, the American Society of Radiologic Technologists, and the American Association of Physicists in Medicine. Founding members of the Alliance convened at Cincinnati Children’s Hospital in July 2007 and developed the concept and messaging campaign. This group then reached out to other professional organizations, swelling the Alliance to a consortium of 13 medical societies. (A complete list of Alliance Organizations is available on the Image Gently Web site.)

“Our guiding force is a simple statement – Image Gently,” explains Dr. Goske, “and our mission is to change practice by educating the entire care team – radiologists, technologists, medical physicists, and referring physicians – about the importance of lowering radiation dose in children.”

The rapid growth of CT pediatric imaging led the Alliance to focus first on this modality. “CT scans save lives but we need to be as prudent as possible when imaging children,” Dr. Goske adds.

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I m a g e g e n t ly c a m p a I g n

The Image Gently message has three key points.

1. Child size the kVp and mA.

2. One single phase scan is often enough.

3. Scan only the indicated area.

The Alliance provides support to institutions seeking to develop pediatric CT protocols. Guidelines, instructions, and a dose worksheet are available online at www.imagegently.org, where healthcare providers can also take the Image Gently pledge. According to the American College of Radiology, over 250 facilities took the pledge on January 22, 2008, the first day of the campaign. One year later, nearly 1,600 medical professionals have taken the pledge and the protocol has been downloaded over 6,000 times.

“We urge radiologists who typically scan adult patients to child size their CT dose. They can also go to our Web site, learn more, and actively engage their institution’s medical physicist in developing protocols for children,” Dr. Goske says. The universal CT protocols recommended by the Alliance are independent of scanner age, make, and model.

“Radiologists have told us that they want to do the right thing and are grateful for this national effort,” Dr. Goske adds, “and the information on our Web site provides them the necessary educational materials to implement this initiative in their institution.” n

Five steps to improving patient care

1. Increase awareness for the need to decrease CT radiation dose to children.

2. Sign the pledge and commit to changing your daily practice by working as a team with technologists, physicists, referring physicians, and parents.

3. Review adult protocols and use the CT protocols available on the Alliance’s Web site to downsize children protocols.

4. Single phase scans are usually acceptable.

5. Scan only the indicated area.

Source: The Alliance for Radiation Safety in Pediatric Imaging. Available at www.imagegently.org

Marilyn Goske, MD, is a radiologist at Cincinnati Children’s Hospital Medical Center and professor at the University of Cincinnati College of Medicine. In January 2008, she was named the Dr. Frederic N. and Carolyn Silverman Endowed Chair for Radiology Education at Cincinnati Children’s. As Chair for the Alliance for Radiation Safety in Pediatric Imaging, Dr. Goske was instrumental in forming the Image Gently initiative.

Dr. Goske earned her medical degree at the University of Connecticut School of Medicine and completed her residency in diagnostic radiology and fellowship in pediatric radiology at Strong Memorial Hospital in Rochester, NY, an affiliate of the University of Rochester. Dr. Goske has also completed a fellowship in medical education at The Cleveland Clinic Lerner College of Medicine’s Division of Education.

Dr. Goske is a member and past president of the Society for Pediatric Radiology, as well as a member of numerous medical associations including RSNA and ACR. In 2008, Dr. Goske was honored as one of the Best Doctors in America by Best Doctors, Inc.,

“ We urge radiologists who typically scan adult patients to child size their CT dose. They can also go to our Web site, learn more, and actively engage their institution’s medical physicist in developing protocols for children.”

– Dr. Marilyn Goske

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M a r k e t i n g

as a result of today’s competitive healthcare market, more hospitals, imaging centers, and physician group practices are marketing their services to referring physicians and patients. yet most traditional medical education programs do not address the “business side” of medicine and so many clinicians are not prepared to develop a marketing strategy.

Marketing your Radiology PracticeBy Frank J. Lexa, MD, MBA, Clinical Professor of Radiology, University of Pennsylvania Medical Center, Professor of Marketing adj., Faculty and Asia Manager, Global Consulting Practicum, the Wharton Graduate School of Business, Adjunct Professor of Biotechnology, Instituto de Empresa, Madrid, España

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M a r k e t i n g

Frank J. Lexa, MD, MBA is a practicing neuroradiologist and a clinical professor of radiology at the University of Pennsylvania School of Medicine. He also serves on the adjunct faculty of the Wharton School in the marketing department and has worked for programs in the Global Consulting Practicum for over a decade. This has taken him to five continents, and he is currently serving as the Asia regional manager for the GCP. He also has an appointment as an adjunct professor of Biotechnology at the Instituto de Empresa in Madrid, Spain. Dr. Lexa lectures, consults, and writes extensively on issues at the interface of healthcare and business science. He is the author of over 60 articles and book and encyclopedia chapters. He serves as the director of the executive education series for the American College of Radiology. Previously, he directed healthcare investments for BTG International and worked as a strategic consultant for the Boston Consulting Group. He was a partner at Philadelphia Ventures, a venture capital firm focusing on high tech medical investments, and he continues to work with start-up companies in that sector. He was educated and did his medical training in Boston, the San Francisco Bay Area, and in Philadelphia.

Marketing is fundamental to business growth. One misconception is that marketing equals advertising or selling and that leads directly to the most common mistake that many physician group practices make: advertise without first developing a strategic marketing plan.

Today’s changing healthcare market represents the single largest source of opportunity – and threat – in diagnostic imaging. Practices face the twin challenges of falling reimbursement rates and rising costs of doing business, all while competition is growing.

While so many factors are beyond our control, two things are certain: marketing is probably the most important success factor that is in your control and it is one of the strongest factors to differentiate your practice from the competition.

Developing a marketing plan

There are many elements to a successful marketing strategy. These include those that you probably expected to see, such as:

Setting up promotions;•

Sales decisions; and•

Advertising: budgets, targets, and channels.•

However, strategic marketing will also encompass most of the major issues that you face in managing an imaging practice, including:

Planning for hiring and purchasing;•

Allocation of resources;•

Setting goals;•

Team dynamics; and•

Managing the day-to-day operations.•

The first step of any marketing initiative is identifying the size of your potential target market. This includes segmenting the market by age, gender, disease type, referral patterns, employment, and psychographic sector. You cannot be everything to everyone, so categorize your facility’s strengths and weaknesses as they pertain to the target.

Next, determine the group to whom you will market your services. Will it be referring physicians, patients, patient’s friends and family, contracting entities such as insurance companies, MCOs or the government, or advocacy organizations? In today’s market, do not underestimate or overlook the power of healthcare consumer marketing.

The four P’s of marketing

All marketing plans center around four core concepts: Product, Positioning, Price and Promotion. Within healthcare, price (reimbursement) is not usually controlled by us so that is generally less applicable than in other situations. However, consider that while price may be fixed, there are other components of value (what else is included in the service) that impact perception of the price paid and subsequently, demand for the product.

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M a r k e t i n g

Elements of a successful marketing strategy lie in the details. Make sure you know who matters the most in the referring physician office. It may not be the clinician. Find out what is most important to your target. Is it scheduling, report turn around time, or other amenities? Use peer-to-peer marketing by developing relationships – don’t be faceless or voiceless – and always measure results. This technique is often underutilized in healthcare, yet it is a smart, high-level, and ethical activity that has enormous impact on physician referrals.

Getting the message out is almost as important as the message itself. Stay focused and on task. There are numerous options for advertising the message beyond radio and television. Many of the most basic, and least expensive, are often overlooked, such as:

Web sites;•

direct mail;•

Phone (while on hold);•

Preview slides at movie theaters;•

Health fairs; and•

Other sponsorship activities.•

Developing the message that differentiates you from your competition relies on a solid understanding of the pitfalls of common claims and core ethical issues. For example, physician quality is, for the most part, an assumed characteristic not a differentiator. Consider this analogy of airplane safety. Would you board a plane if you thought the pilot or aircraft was unsafe?

Also avoid generic claims such as “our physicians are better” or “our equipment is superior.” Provide substance in your message that tells the target what specifically makes your product/service different than the competitor(s). This requires a profound understanding of your customer’s needs, your abilities, and your competition’s capabilities.

Most important, always remember that marketing is the single most effective tool that you have for thriving in an increasingly competitive environment. If done correctly, by encompassing how you produce, position, and promote your service, you will see a far greater impact on your future success. n

In medical imaging, the obvious products are images and reports. Yet, we must look beyond this to understand that we also produce patient and clinician experiences. What experience do you provide that is different, or better, than you competitors? What can you do to enhance that experience?

Proper product positioning requires knowledge of these differentiating factors and how they relate back to your core mission, patient clientele, referring physicians, services, and facilities. Take core mission, for example. Are you an academic center, private practice, or not-for-profit medical center? What is the age, gender, disease state, and insurance acceptance of your patient mix? Are referring physicians specialists or generalists? What type of services do you provide beyond images, reports, and experiences? What is the mix of imaging services within your facility versus your competition?

Promotion is the visible action that you will take to market product and services to the target. First, determine the purpose and message. Are you promoting a specific feature or benefit, or simply building awareness of your name/product/service? A word of caution: if you don’t know what to promote or what your message is, then you should first rethink your marketing strategy before spending any money on promotion.

Promotion is more than advertising

There are several elements to a successful promotion.

1. Who works on your marketing and promotions?

2. What are your key messages?

3. Why did you choose them and how does that affect other organizational decisions?

4. Where and to whom do you promote?

5. When do you launch a campaign?

6. How do you choose channels and vehicles to do your marketing?

Remember again that you cannot be everything to everyone. Therefore, widespread or indiscriminate advertising is almost always the wrong answer. It is costly and difficult to impossible to measure results. A focused promotion that generates a return on investment (ROI) is absolutely essential.

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Learn from the experts: Ge healthcare’s ct Masters series new courses added

e d u c a t i o n

With the GE CT Masters Series, clinicians can learn new CT imaging techniques from experts at a network of CT training centers located throughout the U.S. Learn from some of the top radiologists and cardiologists from around the globe how to realize the full potential of a CT technology investment by maximizing the clinical benefits of advanced applications.

GE Healthcare recognizes that continued advancement in CT imaging technology along with new applications leaves clinicians seeking additional training opportunities. To address this need, GE evaluates its CT Masters Series training programs to help clinicians stay abreast of the latest tools and techniques in CT. Several new courses have been added and are listed below. n

Cardiac CTA for CT TechnologistsWith Judy Lane, RT(R)(CT) and Rob Jennings, RT(R)

3 Day Offering Offers 14 CE Fairfax Radiological Consultants 8318 Arlington Blvd., Room 302A Fairfax, VA 22031

CT Colonography Training for the Gastroenterologist: A Hands-On CourseThis course is held in partnership with the AGA Institute

With Abraham Dachman, MD, FACR

2 Day Offering Ge healthcare institute N16 W22419 Watertown Road Waukesha, Wi 53186

Peripheral CT Angiography

With Matthew Budoff, MD and David Shavelle, MD

2-1/2 Day Offering Offers up to 9.5 CME St. John’s Cardiovascular Research center harbor ucLa Medical center 1124 W. Carson Street Torrance, CA 90502

Hands-on, in-person training is a valuable addendum to any physician’s education.

Cardiac CT Educational Toolkit - 50 cases on DVDs: Interpreting the Heart: A visual guide using CardIQ™ Xpress. See page 8 for more information or go to www.gehealthcare.com/cardiactoolkit.

Virtual Colonoscopy Educational Toolkit - 30 cases on CDs: Interpreting the Colon: A visual guide using AdvantageCTC™ Go to www.gehealthcare.com/colontoolkit for more information.

For more information and to register for a CT Masters Course please go to: www.gehealthcare.com/gectmasters

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GE Healthcare


You stake your reputation on providing premium care. We stake ours on helping you do it. That’s why the Discovery CT750 HD delivers high-definition images for each scan: so referring physicians get the assurance of robust, decisive results. Built around the industry-exclusive Gemstone™ detector, the system puts your clinical ability on the technological edge. And above all, it operates at up to 50% less dose to your patients — which is what matters most. CT Re-imagined.


What matters most to your mission.


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GE Healthcare

CT-0387-02.09-EN-US


What’s the difference between making a confident diagnosis and needing another look? Clarity. So we designed our new Discovery CT750 HD with your needs in mind, enabling you to see the finest details for the first time. Powered by the industry’s only Gemstone™ detector, it gives you a level of high-definition detail that makes the line between uncertainty and confidence clearer than ever. CT Re-imagined.


A fine line never looked so obvious.


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