Contrast enhanced MR angiography in the assessment of relevant stenoses in occlusive disease of the pelvic and lower limb arteries: diagnostic value of a two-step examination protocol in comparison to conventional DSA.
OBJECTIVE
Contrast-enhanced MRA (ce-MRA) has been claimed by many authors as a replacement of conventional angiography evaluating peripheral arterial occlusive disease. However, reliable detection of relevant stenoses (>70%) has to be provided for planning vascular interventions. Only few data in the literature focuses on this crucial problem. The purpose of this study was to evaluate this topic using a two-step body-coil-based MRA protocol.


METHODS
Forty three patients presenting with 82 stenoses >/=50% and 61 stenoses >70% on conventional catheter angiogram received fast Gadolinium-DTPA-enhanced high resolution 3D MR angiography at 1.5 T covering the pelvic and peripheral vascular tree in two examination steps using the body-coil. The data were evaluated double-blinded by three readers distinguishing moderate (50-70%) from severe stenoses (>70%).


RESULTS
Overall sensitivity/specificity/accuracy was 84/60/70% evaluating 143 segments. Specificity was rather poor in the iliac (58%) and crural (50%) region and moderate in the femoral and popliteal level (73%). The negative predictive value ranged between 78 and 91%. The grade of stenosis tend to be overestimated rather than underestimated in all levels with positive predictive values between 55 and 78%.


CONCLUSIONS
Body-coil-based contrast-enhanced MRA has limited potential in distinguishing moderate from severe stenoses in peripheral occlusive disease. Overestimations are more common than underestimations. Both occur mainly in small-sized crural arteries but also in larger iliac arteries where vessel course in partition direction may cause inadequacy between voxel size and lumen diameter in severe stenosis.
Winterer
Jan Thorsten
JT
Department of Diagnostic Radiology, University Hospital Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany. winterja@ruf.uni-freiburg.de
Schaefer
Oliver
O
Uhrmeister
Peter
P
Zimmermann-Paul
Gesine
G
Lehnhardt
Stefan
S
Altehoefer
C
C
Laubenberger
J
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction; D001157:Arterial Occlusive Diseases / Q000175:diagnosis*; D003287:Contrast Media; D005260:Female; D005263:Femoral Artery / Q000473:pathology*; D006801:Humans; D007083:Iliac Artery / Q000473:pathology*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011150:Popliteal Artery / Q000473:pathology*; D011446:Prospective Studies; D012680:Sensitivity and Specificity
D003287:Contrast Media