NonNon--Contrast MR AngiographyContrast MR Angiography

Robert R. Edelman, M.D.Robert R. Edelman, M.D.Dept. of RadiologyDept. of Radiology

NorthShore University HealthSystemNorthShore University HealthSystemFeinberg School of Medicine, Northwestern UniversityFeinberg School of Medicine, Northwestern University

Nephrogenic Systemic Fibrosis:Game-changer for CE-MRA

• NSF can be prevented with simple precautions, but damage is already done…

• The “go to” imaging test for patients with impaired renal function is now viewed by many clinicians as hazardous• Decreased referrals for renal and peripheral MRA

– hard to recapture patients• Substantial additional cost for POS eGFR testing equipment

Up to 50% Reduction in Contrast Agent Dose For 3T MRA

Total of 20cc GdDTPA(dual bolus, 3 stations)

Finn JP et al. Radiology2008; 248:680

Gadobenate dimeglumine

Gadopentetate dimeglumine

Gadobenate dimeglumine

Gadopentetate dimeglumine

Gadobenate dimeglumine

Gadopentetate dimeglumine

Knopp MV et al. Knopp MV et al. J Magn Reson ImagingJ Magn Reson Imaging. 2003;17:694. 2003;17:694--702.702.

Use of Higher Relaxivity Contrast Agent Allows Decreased Dosage

Whole body MR MRA/MRV with Ferumoxytol (Equilibrium Phase)

Total Acquisition Time: 5minutes 45 seconds for 8 stations

*Note lack of renal parenchymal enhancement

How About Not Using Any Contrast Agent How About Not Using Any Contrast Agent for MRA?for MRA?

Potential contrast mechanisms for unenhanced MRA:Potential contrast mechanisms for unenhanced MRA:

Gated Subtraction (subtraction of images acquired at Gated Subtraction (subtraction of images acquired at different phases of the cardiac cycle)different phases of the cardiac cycle)SpinSpin--Labeling (subtraction of image sets prepared byLabeling (subtraction of image sets prepared bydifferent RF pulses)different RF pulses)TimeTime--OfOf--Flight (TOF) effectsFlight (TOF) effectsPhasePhase--ContrastContrastFlowFlow--independent mechanismsindependent mechanisms

Time of Flight Non-Contrast MRA

Good for Intracranial Vessels…….Bad for Vessels in Body

bSSFP: Improve Background Suppression Using an Inversion Pulse time-SLIP, native trueFISP

Takahashi J et al. Proceedings of Annual Mtg ISMRM 2007:179

•X. Bi, PhD Siemens Medical Solutions

Native trueFISP MRA with Navigator Gating

Renal Transplant

CE-MRA NC-MRA

Gated Subtractive MRAGated Subtractive MRA•• Fresh Blood Imaging (FBI): TurboSE readout (1)Fresh Blood Imaging (FBI): TurboSE readout (1)•• FlowFlow--sensitive Dephasing (FSD): bSSFP readout (2)sensitive Dephasing (FSD): bSSFP readout (2)

1. Miyazaki et al. Radiology 2003; 227:8901. Miyazaki et al. Radiology 2003; 227:890--8968962. Fan et al. Magn Reson Med 2009; 62:1523–1532.

Diastole Systole

Fresh Blood Imaging•Uses 3D Half-Fourier fast SE for data acquisition• Use cine PC todetermine ECG delayfor maximum andminimum flow velocity• Subtraction showsarteries while eliminatingbackground tissues• Scan time only a fewminutes• Sensitivity/specificity for>50% stenosis 94%/94%

Miyazaki et al. Radiology 227:890-896, 2003; Proc. ISMRM 14 (2006):1929

• Fast

• Easy to use

• Insensitive to:

• Patient motion

• Heart rate

• Flow patterns

• Robust imaging of pelvis arteries

Ideal Methodology forUnenhanced MRA

1

2

3

4

5

6

7

8

9Quiescent Interval Single Shot (QISS) MRA:Multi-station Acquisition Method

QISS1.2x1x1mm

AxialDist= -20

400 matrix40cm fov

QISS3x1x1mm

AxialDist= 0

400 matrix40cm fov

QISS MRA

PATIENT JR87 YEAR OLD MALEACHING LEGSATRIAL FIBRILLATION

CE-MRA

Patient KW66 year old maleBilateral claudication

QISS MRA CE-MRA

QISSMRA CE‐MRA

QISS CTA

Patient NCPatient NC88 year old male with 88 year old male with

claudication, diabetes and claudication, diabetes and atrial atrial fibrillation

Sensitivity 93.9% Specificity 90.6%

Specificity 89.3%Sensitivity 96.4%

Sensitivity 96.5% Specificity 95.8%

ZERO DOSE (QISS) MRA STRATEGYZERO DOSE (QISS) MRA STRATEGY

Sensitivity 95.8%

Specificity 92.4%

NPV 96.7%

PPV 89.8%

2DTOF QISS

Arterial Spin Labeling:20 Second “STAR” Non-Contrast Carotid MRA

Koktzoglou , Edelman ENH

Inversion tagging pulse

DiffeenceOf tagged andUntagged Images

Arterial SpinArterial Spin--Labeled MRA (ASL)Labeled MRA (ASL)

Dixon et al. Magn Reson Dixon et al. Magn Reson Med 1986; 3:454Med 1986; 3:454--462462

ECGECG

RR

baseline imagebaseline image tagged imagetagged image

RF tagRF tag

arte

rial s

egm

ent

of in

tere

star

teria

l seg

men

tof

inte

rest

baseline imagebaseline image tagged imagetagged image

direction of blood

flow

direction of blood

flow

tag

arteryartery

•• Contrast predicated on differential vascular signal Contrast predicated on differential vascular signal created by preparatory RF pulsescreated by preparatory RF pulses

Non-Contrast MRA of the HandsUsing FSD

CE-MRA Non-contrast MRA

Patient 3Severe disease

Direct Thrombus ImagingFraser D et al. Ann Intern Med. 2002;136:89-98

• All clots > 8 hours appeared bright with water-excite MP-RAGE sequence• Sens/spec within each of the venous segments ranged from 91% to 100%; same below knee (101 patients)

Steady State Free Precession (SSFP)-Based MR Venography

Cantwell CP et al. JVIR 2006; 17:1763–1769

Flow-Independent MRA:STARFIRE

NonNon--Contrast Evaluation of Acute DVTContrast Evaluation of Acute DVT

Water-excite MP-RAGE STARFIRE Dbl dose Gd-3DMRAdelayed - arterial

Pitfalls of Non-Contrast MRA

• Stenosis exaggeration from accelerating or turbulent flowwith bSSFP and turboSE readouts• Sensitivity of bSSFP sequences to B0 inhomogeneity• Mistiming of delays for peak and minimal flow velocities with FBI/native SPACE• ECG mis-triggering• Stair-step artifact with 2D acquisitions

Conclusions• NSF has changed landscape for MR angiography• Contrast-enhanced MRA can be safely performedand NSF entirely avoided if proper screening proceduresare undertaken and appropriate contrast agentsare used (but remains disruptive to work flow)• Newer non-contrast MRA techniques may permitscreening for vascular disease with high negative predictive value, thereby eliminating need for contrastagents in many if not most cases• Only limited clinical validation has been published:lack of technique uniformity across vendors• With proper validation, will likely reduce or eliminate need for contrast agents in many MRA applications, thereby reducing cost and morbidity

Acknowledgments• Ioannis Koktzoglou, Ph.D. NorthShore• Philip Hodnett, M.D. NorthShore/NMH• John Sheehan, M.D. NorthShore• Debiao Li, Ph.D. NMH• Xiaoming Bi, Ph.D. Siemens Healthcare• Christopher Glielmi, Ph.D. Siemens Healthcare