8/15/2012

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Endowed lectureship fitting

memorial to Lee Prewitt, MD “In his work in radiology, Lee loved the children,” said

Cindy Prewitt, wife of Lee H. Prewitt, MD. “He treated

each one of them as if they were his own.” Dr. Prewitt

died in December 2007 after 31 years as a physician

in the Radiology Department at Children’s Hospitals

and Clinics of Minnesota.

An early member of the hospital’s radiology program,

Dr. Prewitt was committed to Children’s and to life-long

learning. Cindy, and children, Jenna and Bryce,

established a fitting memorial to him focused on health

care education at the hospital.

The inaugural Lee H. Prewitt Memorial Lecture was

held in April 2009 on “Pediatric Uroradiology - A

Reminiscence” presented by Dr. Prewitt’s mentor,

Robert L. Lebowitz, MD, Professor Emeritus of

Radiology, Children’s Hospital Boston and Harvard

Medical Center. Each year the Lee H. Prewitt Memorial

Lecture will be part of Grand Rounds.

“There have been many changes over the years in

how physicians are trained, as well as how they keep

up with new advances in pediatric health care. Lee

was always striving to be the best he could be, and I

think he would appreciate how this lectureship

continues that spirit by bringing people together to

enhance the care of children,” said Cindy.

Working with Children’s Foundation, Cindy has

ensured that the lectures will continue every year

through her annual gift, and in her estate planning she

has created an endowed fund named after Lee that will

support the lecture series permanently.

Viewing Time

This presentation will take

approximately one hour to complete.

4

Target Audience

This program is designed for primary care physicians.

Other health care professionals working with patients and their families may also find this program of interest.

Faculty Disclosure It is the policy of Children’s Hospitals and Clinics of Minnesota to ensure balance, independence, objectivity, and scientific rigor in all its educational programs. Our faculty have been asked to disclose to our program audience any real or apparent conflicts of interest related to the content of their presentations.

They have also been requested to let you know when any products mentioned in their presentations are not labeled for the use under discussion or are still under investigation.

6

Speaker Faculty Disclosure

Peter J. Strouse, MD has disclosed no actual or apparent conflict of interest in relation to this educational activity.

During this educational activity Dr. Strouse will not be discussing the off-label use of any commercial or investigational product not approved for any purpose by the FDA.

8/15/2012

2

Imaging of Appendicitis:

What can We Do for You?

Pediatric Grand Rounds: August 16, 2012

Peter J. Strouse, M.D., F.A.C.R.

Director, Section of Pediatric Radiology

Director, Pediatric Radiology Fellowship Program

C.S. Mott Children’s Hospital

Professor, Department of Radiology

University of Michigan Health System

Ann Arbor, Michigan,

Imaging of Appendicitis:

What can We Do for You?

A lecture about the imaging of appendicitis along

with a suggested algorithm for the proper use of

physical exam, US, and CT

Program Objectives

Upon completion of this program, participants should be able to:

Discuss the imaging findings of appendicitis.

Present the goals of imaging for appendicitis.

Propose a paradigm for imaging of appendicitis.

Disclaimer

Children’s Hospitals and Clinics of Minnesota accepts no responsibility for the materials presented through these Grand Rounds seminars. Each professional presenter assumes all responsibility for maintaining confidentiality or obtaining authorization, in accordance with all applicable laws.

Accreditation

Children’s Hospitals and Clinics of Minnesota is accredited by the Minnesota Medical Association to provide continuing medical education for physicians.

Children’s Hospitals and Clinics of Minnesota designates this educational activity for a maximum of 1 AMA Category 1 Credit

TM toward the AMA Physician’s Recognition Award.

Each Physician should only claim credit for the actual time he/she spent in the activity.

Retention of CME Records

It is the policy of Children’s Medical Education program that we cannot offer to retain CME records for physicians attending or viewing the online CME activity.

The Minnesota Medical Association designates that physicians are responsible for maintaining their own CME records.

8/15/2012

3

Receiving CME Credit

To receive CME credit, you must view the entire program. When the program is completed, click the Post Test button on the interface to access the Post Test.

You must successfully pass the Post Test to receive CME credit.

Imaging of Appendicitis:

What can We Do for You?

Peter J. Strouse, M.D., F.A.C.R.

Professor

Director, Section of Pediatric Radiology

Director, Pediatric Radiology Fellowship Program

C.S. Mott Children’s Hospital

Department of Radiology

University of Michigan Health System

Ann Arbor, Michigan, U.S.A.

Disclosures

None

Objectives

1) Discuss the imaging findings of

appendicitis

2) Present the goals of imaging for

appendicitis

3) Propose a paradigm for imaging of

appendicitis

The Appendix

• Midgut derivative

• Outpouching of cecum by 8th

week of gestation

• No known function

• With normal rotation and

fixation of cecum in right

lower quadrant

• Location varies

• Length varies

(adult: 9 cm average length)

Obstruction (lymphoid hyperplasia,

Inspissated feces,

appendicolith, etc.)

Bacterial Overgrowth

Mucous Production

Inflammation, Distention

Increased Pressure

Venous Obstruction

Necrosis

Bacterial Translocation

Bacteremia

Sepsis

Gangrene

Perforation

Peritonitis Phlegmon

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Who gets Appendicitis?

Lifetime risk:

7-8%

Addiss DG, et al. The epidemiology of appendicitis and

appendectomy in the United States. Am J Epidemiol

1990;132: 910-925

Capacity: 109,901

Aaron

Friedkin, MD

USA: 250,000 - 680,000 cases of

appendicitis per year (all ages)

Prompt Diagnosis Decreases

Morbidity (& Mortality) In hospital delay in diagnosis

• Higher complication rate (58.6% vs. 28.9%)

• Higher perforation rate (23.1% vs. 18.9%)

• Higher abscess formation rate (35.8% vs. 10.1%)

• Needed more drain procedures (5.7% vs. 0.4%)

• More hemicolectomies, SB laceration repairs, small bowel

resections

• Longer length of stay (10.4 days vs. 2.9 days)

• Higher cost ($53,500 vs. $17,900)

• Higher mortality (0.68% vs. 0.03%)

National database – 683,016 hospitalizations for appendicitis

Lee J, et al. Missed opportunities in the treatment

of appendicitis. Pediatr Surg Int 2012;28:697-701

Why Image?

• ~ 1/3 Atypical Presentation

Goal: hasten diagnosis, reduce complications

from delayed diagnosis, reduce negative

laparotomy (laparoscopy) rate

Goal: make alternative diagnoses

• Identify complications

Goal: identify perforation and/or abscess,

which may alter therapy

Is imaging required?

“The diagnosis of appendicitis . . .

is established by repeated clinical

examination by a skilled clinician.”

“Appendicitis is a diagnosis you make

with your hands”

Anthony Lander, FRCS.

Pediatr Radiol 2007;37:5-9

Michael D. Klein, MD.

Pediatr Radiol 2007;37:1114

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• In general, literature supports that

imaging (US, CT) has decreased the

negative appendectomy rate

• Hastens diagnosis

• Boys > 5 years old - ? omit imaging

Bachur RG, et al. Diagnostic imaging and

negative appendectomy rates in children:

effects of age and gender. Pediatrics, 2012

Is imaging required? Problems with the Appendicitis

Imaging Literature

• Few direct prospective comparisons

• Studied populations vary and are poorly defined

• Results are technique dependent

• Evolving technology

• Role of clinical evaluation is usually overlooked

• Equivocal cases variably handled

• Acceptance of gold standard (path/surgery/f/u)

• Whatever your point, there is a paper to prove it

Three Questions asked of

the Radiologist:

1) Does the patient have appendicitis?

2) If not, is there another diagnosis?

3) If yes, is it perforated?

= Appendix

= Appendicolith

= Something else

1) Does the patient have

appendicitis?

Appendicitis: Pre-Imaging Era

• 1980’s and prior

• Dx made based on history, physical

exam, labs, +/- radiographs

• Barium enema

• Negative appendectomy rate ≈ 15-20%

• Perforation rate ≈ 20-30%

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Radiography

Advantages

• Inexpensive

• Quick

Disadvantages

• Not sensitive

• Radiation

Radiography

• Usually normal in

w/o perforation

11-year-old girl

Radiography

• Appendicolith (5-10%) • Appendicolith (5-10%)

• Ileus

• Mass effect

Radiography

Are radiographs useful?

• May suggest alternative diagnosis

• May guide choice of US vs CT

• Not necessary if already

committed to doing a CT

Foreign

Body

Appendicitis

2 1/2-year-old boy

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Barium Enema - Historical

Image here

8-year-old girl

Ultrasound

Puylaert, JBCM

“Acute Appendicitis: Ultrasound Evaluation

Using Graded Compression”

Radiology 1986;158:355-360

a

v Psoas m. v

• Linear array transducer

• Graded compression

9-year-old girl

Appendicitis

9-year-old girl

Ultrasound Technique

• Start in area of pain/tenderness

• Then search systematically

From: Baldisserotto &

Marchiori, AJR 2000

Appendicitis

Cecum Cecum

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Normal Appendix

• ≤ 6 mm diameter

• Compressible

• Non-tender

8-year-old boy

Normal Appendix

15-year-old boy

Abnormal Appendix

• Non-compressible

• Blind ending

• Tubular structure

• > 6 mm diameter

• Tender

• +/- Appendicolith

• +/- Secondary findings

12-year-old boy

Abnormal Appendix = “non-compressible”

Appendicitis

13-year-old boy

Appendicitis

8-year-old boy

Appendicitis

11-year-old boy

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Appendicitis

7-year-old boy

Cecum

Appendicitis

7-year-old boy

16-year-old boy

Appendicitis

Appendicitis

Ultrasound Advantages

• No sedation

• No prep

• No radiation

• Realtime

• Spatial resolution

• Pelvis/GB/Urinary

tract

• Low FP rate

Disadvantages

• Operator dependent

• Technique dependent

• Takes time

• May be painful • Normal appendix may

not be seen • High FN and/or

indeterminate rate

• Less accurate than CT for perforation

Limitations of US

• Large or obese patients

• Bowel gas, guarding

• Anomalous appendix position

• “Not as accurate as CT”

• Acceptance and understanding of referring clinician (and surgeon)

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Appendicitis

4-year-old boy

Is it necessary to see the

normal appendix?

10-year-old boy

Is it necessary to see the

normal appendix?

Stewart et al, Sonography for Appendicitis: Nonvisualization of

the Appendix Is an Indication for Active Clinical Observation

Rather Thank Direct Referral for Computed Tomography. J Clin

Ultrasound 2012

• 260/400 patients had non-visualization

of the appendix on ultrasound

• 16/260 (6.2%) had appendicitis

• Clinical observation; not CT in all

Pooled

Sensitivity

Pooled

Specificity

US 88% 94%

Ultrasound is a Good Test

Doria AS, et al. US or CT for Diagnosis of

Appendicitis in Children and Adults? A Meta-

Analysis. Radiology 2006;241:83-94

Sensitivity: 50-100%

Specificity: 88-99%

Maybe not ?

Taylor GA, Suspected appendicitis in children: in search of the

Single best diagnostic test. Radiology 2004;231:293-294

Two largest studies (>5000 children)

• Sensitivity – 90-92%

• Specificity – 97-98%

• PPV – 82-90%

• NPV – 98%

Hahn HB, et al. Pediatric Radiology 1998

Schulte B, et al. Eur J Radiol 1998

Ultrasound is a Good Test

8/15/2012

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Wiersma et al

• Normal appendix seen in 82% of asymptomatic children

• 15 min maximum time allowed

Hahn et al

• Normal appendix seen in 82% of patients w/o acute appendicitis

• 20 min maximum time searching

How good can Ultrasound be?

Hahn HB, et al. Pediatric Radiology 1998

Wiersma et al. Radiology 2005

• Prospective study

• 425 children – 199 proven appendicitis

• Used supplemental views

• 20 min average

• Sensitivity 98.5%

• Specificity 98.2%

• PPV 98.0%

• NPV 98.7%

Baldisserotto & Marchiori, AJR 2000

How good can Ultrasound be?

• United States

• Retrospective review of prospective Dx’s

• 81 pts to OR w/o CT or US

– 20% FP rate (16 = normal appx)

• 389 imaged (382 US, 3 CT, 4 US&CT)

– 137 to OR

– 3% FP rate (4 = normal appx)

Hernandez JA, et al. Imaging of acute appendicitis: US as the

primary imaging modality. Pediatr Radiol 2005;35:392-395

How good can Ultrasound be?

• If positive → OR

• If negative w/ high suspicion or

equivocal

→ CT

→ Observation

Ultrasound

Computed Tomography (CT) Normal Appendix

• < 7 mm diameter

• No inflammatory changes

• +/- filled with contrast

• +/- filled with air

15-year-old girl

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Normal appendix

16-year-old girl

Abnormal Appendix

• ≥ 7 mm diameter

• Inflammatory changes

• Edema

• Hyperenhancement

• Fluid

• Cecal/TI wall thickening

• Appendicolith

Appendicitis Appendicitis

11-year-old girl

CT Advantages

• Global coverage

• See appx more

• Higher

sensitivity

• Better for perf

Disadvantages

• Radiation

• IV access

• Prep

• Sedation

• Not realtime

CT & Radiation – Should

you be concerned?

Ultrasound - 0 mSv

CT - 3 mSv

8/15/2012

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0%

10%

20%

30%

40%

50%

60%

20 40 60 80 100

Mean Dose (mSv)

Excess R

ela

tive R

isk

of

Can

cer

Mo

rtali

ty

Brenner & Elliston, Radiology 2004

What about the radiation?

• CT is the largest source of

radiation in diagnostic imaging.

• Most patients with appendicitis

are children or young adults.

• The long-term effects are still

not fully defined.

1/1000 – 1/2000 = the approximate increased

risk of a fatal cancer later in life due to a CT

Brenner et al, Estimated risks of radiation-induced

cancer from pediatric CT. AJR 2001;176:289-296

What about the radiation?

CT Technique • CT with no contrast

• CT with IV contrast

• CT with oral contrast

• CT with rectal contrast

• CT with IV and oral contrast

• CT with IV, oral and rectal contrast

• CT with IV and rectal contrast

• CT with IV and oral contrast & rectal air

IV Contrast Advantages

• Adds min’l time

• Inflamed appx

enhances

• Defines bowel wall,

abscess, etc.

• Other Dx’s

Disadvantages

• IV access

• Contraindications

- renal failure

- Hx of contrast

reaction

Oral Contrast Advantages

• Opacification of

bowel

Disadvantages

• Delay due to Prep Time

• Drink or NG

• Incomplete transit

Rectal Contrast

Rao et al, Radiology 1997;202:139-144

5 reasons not to use

rectal contrast:

1. Patients don’t like it

2. Techs don’t like it

3. Lengthens time in CT

scan room

4. Adds radiation dose due

to rescans

5. No proof that better than

other techniques

8/15/2012

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Appendicitis CT: How we do it

• Oral contrast prep (2-4 hours)

• IV contrast

• 64 slice helical CT

• mAs appropriate for size

• Whole abdomen & pelvis

• 0.625 mm axial images

• Recons: 5 mm axial; 2 mm Sag & Cor 13-year-old girl

0.625 mm

5 mm

2 mm

2 mm

Appendicitis CT: How we do it

CT is “Operator Dependent”

5-year-old boy – 8 mAs

CT is “Reader Dependent”

Resident

General

Radiologist

Abdominal

Imaging

Specialist

Sensitivity 81% 88% 95%

Specificity 94% 94% 100%

PPV 98.6% 98.7% 100%

NPV 50% 68% 81%

In’t Hof et al. Interobserver variability in CT scan interpretation for

suspected acute appendicitis. Emerg Med J 2009;26:92-94

Pooled

Sensitivity

Pooled

Specificity

CT 94% 95%

CT is a Good Test

Doria AS, et al. US or CT for Diagnosis of

Appendicitis in Children and Adults? A Meta-

Analysis. Radiology 2006;241:83-94

Is CT really that much

better than Ultrasound?

8/15/2012

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Pooled

Sensitivity

Pooled

Specificity

US 88% 94%

CT 94% 95%

CT vs. US

Doria AS, et al. US or CT for Diagnosis of

Appendicitis in Children and Adults? A Meta-

Analysis. Radiology 2006;241:83-94

CT is NOT 100% accurate

5% are Equivocal

CT: Equivocal Cases

• Adults

• Retrospective

• 13% (172/1344) cases = “equivocal”

• ~30% of equivocal cases had

appendicitis

Daly CP, et al. Incidence of acute appendicitis in patients with

equivocal CT findings. AJR 2005;184:1813-1820

14-year-old girl

Appendicitis ?

10-year-old girl

9-year-old boy

CT Equivocal Cases

• Serial PE (by a surgeon)

• Treat based on clinical assessment

• Do an ultrasound

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• 104 patients had CT followed by US

– 35 CT suggested appy, but atypical pain

– 16 CT equivocal for appy

– 53 CT negative, but persistent

symptoms suggesting appy

Is there Utility to US after CT?

Jang, et al. What is the complementary role of ultrasound

evaluation in the diagnosis of acute appendicitis after CT?

European Journal of Radiology, 2009

Is there Utility to US after CT? CT # US

Definite appy 3 3 pos

Probably appy 32 25 pos

7 neg

Equivocal appy 16 7 pos

9 neg

Probably not 12 2 pos

10 neg

Negative 41 5 pos

36 neg

By surgery &

follow-up:

US was correct in

every case

Jang, et al. What is the complementary role of ultrasound

evaluation in the diagnosis of acute appendicitis after CT?

European Journal of Radiology, 2009

Coming attractions:

• Lower dose CT

– Iterative reconstruction (ASIR, etc.)

– Model based reconstruction (VEO, etc.)

• MRI - Moore et al (2012)

– Sens 97.6%, Spec 97.0%

– PPV 88.9%, NPV 99.4%

– N = 208 patients

Moore MM, et al. MRI for clinically suspected appendicitis:

an implemented program. Pediatr Radiol, 2012

11-year-old boy

13-year-old girl

Images c/o

MM Moore, MD

Hershey, PA

12-year-old boy

13-year-old boy

14-year-old girl

2) If not appendicitis, is

there another diagnosis?

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DDx of Appendicitis • Ovarian pathology – torsion/tumor/cyst

• Pelvic inflammatory disease (PID)

• Inflammatory bowel disease – Crohn

• Pyelonephritis (on right)

• Renal stone (on right)

• Omental infarction/Epiploic appendagitis

• Intussusception

• Malrotation

• Bowel obstruction

• Meckel diverticulitis & related conditions

• Urachal remnant

• Intra-abdominal neoplasm

• Etc., Etc., Etc.

17-year-old girl

Pyelonephritis

Crohn Disease 15-year-old girl Ovarian Torsion

7-year-old girl

Ovarian Neoplasm (Teratoma w/ torsion)

11-year-old girl

Intussusception

2 1/2-year-old boy

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Pelvic Inflammatory

Disease (PID)

15-year-old girl

Renal Stone

(@ UVJ)

16-year-old girl

Omental

Infarction

5-year-old girl

15-year-old boy

Clinical Hx: Abdominal pain & fever

Pneumonia

Malrotation w/ volvulus

5-year-old boy

3) If it is appendicitis, is it

perforated?

. . . and can you drain it?

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Perforation • Specific signs:

– Abscess

– Extraluminal gas

– Extruded

Appendicolith

• Less specific:

– Ileus/SBO

– Phlegmon in RLQ

– Substantial free fluid

75% accuracy of

CT for perforation

Fraser JD, et al. Accuracy of

computed tomography in

predicting appendiceal

perforation. J Pediatr Surg

2010;45:231-215

• Echogenic periappendiceal fat

4-year-old girl

Perforated

Appendicitis

• Echogenic periappendiceal fat

• Disruption of appx wall

• Abscess

10-year-old boy

Perforated

Appendicitis

13-year-old girl

Perforated Appendicitis

10-year-old boy

Perforated Appendicitis

• SBO

3-year-old girl

Perforated

Appendicitis

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Perforated

Appendicitis

Perforated

Appendicitis

• Phlegmon

17-year-old boy

• Abscess

Perforated

Appendicitis

• Abscess

• Extruded

appendicolith

4-year-old boy

Perforated

Appendicitis

1) Abscess ?

2) Size ( ≥ 3 cm)

3) Access

Can you* drain it?

2-year-old girl

* Pediatric Interventional Radiology (Peds IR)

Expectations of Imaging

#1 – Don’t miss appendicitis

#2 – Differentiate non-perforated from

perforated appendicitis (guide Tx)

#3 – Make alternative diagnoses

#4 – Do it safely & efficiently

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Tenants for an Imaging

Algorithm for Appendicitis

1. Begins with a good history and physical examination,

supplemented by laboratory studies (+/- radiography).

2. Involves both US and CT, but not necessarily both in

a given patient.

3. Neither CT nor US is appropriate for every patient.

4. Depends on the resources available, the patient(s)

being studied and the desired information to be

obtained.

5. No imaging study is perfect.

6. Imaging findings may be equivocal.

7. Imaging findings should not be interpreted in a vacuum.

8. Avoiding radiation is good.

9. Imaging should improve the outcome and never lessen the outcome.

Tenants for an Imaging

Algorithm for Appendicitis

Step 1 – Physical Exam Step 2 – Ultrasound*

* If suspect perforation, may go straight to CT

Step 3 - CT

PE

Equivocal Alt Dx Negative Positive,

? perforation

CT > US

Surgery

Conservative Tx

US

Surgery

US

Serial PE’s

Home

Back to ER or

Pediatrician

Appropriate

Work-up &

Treatment

Positive,

No perforation

STEP 1

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US

Positive Alt Dx Equivocal

Surgery

CT CT

Home

Back to ER

or

Pediatrician

Appropriate

Work-up &

Treatment

CT

Surgery

Conservative Tx

Positive,

w/ perforation Negative,

High Susp

Negative,

Low Susp

STEP 2

CT

Positive Positive

Perforation

Negative Equivocal Alternative Dx

STEP 3

Surgery Conservative Tx

Surgery

Home

Back to ER or

Pediatrician

Surgeon

Decides US if not

already done

Appropriate

Work-up &

Treatment

Strouse PJ. Pediatric appendicitis: an

argument for US. Radiology 2010;255:8-13

Effects of the Imaging

Algorithm • Decrease over-utilization

• US as the primary modality

– Decrease radiation exposure

– Decrease cost ?

• Overall sensitivity of algorithm high as

patients with high index of suspicion

still proceed to CT

• Does not increase perforation rate

van Breda Vreisman AC, Kole BJ, Puylaert JB. Effect of

ultrasonography and optional computed tomography on the

outcome of appendectomy. Eur Radiol 2003;13:2278-2282

The Role of Ultrasound

• The utility of ultrasound is greater if we are more skilled at ultrasound

• The sensitivity needs to be good

– Some false negatives/equivocals are tolerated

• The specificity needs to be excellent

– False positives are less tolerated

• If avoiding radiation is a goal, US with less than optimal sensitivity is still useful

What is the acceptable false

negative appendectomy rate?

1980’s – 15 - 20%

2012 – ? ? ?

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What is the acceptable

negative CT rate?

Approximate prevalence

of appendicitis in those

who are imaged = 31%

Conclusions

• Appendicitis - probably the single

greatest opportunity to reduce

radiation for a particular Dx in

pediatric medicine

• Physical examination still plays a

(large) role

• Ultrasound and CT are

complementary, not competitive

Thank you

Question

Given the importance of technology

and operator skill in this process,

would it be your suggestion that

pediatric patients only be imaged at

children’s hospitals?

Question

What’s the largest caliber positive

appendix that you’ve seen and the

smallest caliber appendix?

8/15/2012

24

Question

You said that your average dose of

radiation for a CT is 3 mSv…

How is that measured?

Question

What is your surgeons’ protocol in

terms of when they will operate on

confirmed cases of appendicitis?

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