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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