Gadolinium-Enhanced MR Angiogra p hy of Arterial Occlusive in Lower Extremity: Comparison with Conventional Digital Substraction Angiography

ABSTRACT

PURPOSE: To compare the diagnostic value of gadolinium-enhanced MR angiography with that of conventional digital substraction angiography for the evaluation of lower extremity arterial occlusive diseases. MATERIALS AND METHODS: In 26 patients with symptomatic lower extremity arterial occlusive disease, both conventional digital substraction angiography(DSA) and gadolinium-enhanced MR angiography (CE-MRA) were performed during the same week. MR angiography was performed using three-dimensional gradient-echo ac-quisition before, and two sequential acquisitions after, the administration of gadolinium(0.2 mmol/kg). In 23 patients, two separate, contiguous areas were scanned using additional doses. In three patients, only one field with a suspicious lesion was scanned. Three radiologists independantly analysed the CE-MRA and DSA find-ings of each vascular segment(20 segments per arterial tree) for the presence of obstructive lesions; the grade assigned was either mild or none (>50 %), stenotic(50 %-99 %),or occlusion(100 %). RESULTS: From among a total of 462 segments, DSA detected 99 which were significantly narrowed (stenosis, 33; occlusion, 66). Using MR angiography, 102 segments(stenosis 39; occlusion, 63)were identified, and 94 lesions (stenosis, 32; occlusion 62) were graded correctly. Seven lesions were overestimated and four were un-derestimated. For the detection of hemodynamically significant stenosis or occlusions using MR angiography, sensitivity, specificity, and diagnostic accuracy were 95%, 98%, and 98% (G=0.995, P<0.001), respectively. To prove the absence of lesions, we repeated DSA in two patients with arterial spasm due to puncture. Three occluded segments seen on DSA, which revealed intact segments on MR angiography, suggested slow distal flow after reconstitution. CONCLUSION: For the evaluation of lower extremity arterial occlusive disease, the diagnostic value of gadolini-um-enhanced MR angiography is comparable with that of digital substraction angiography. The advantages of the former are the absence of puncture-related spasm and visualization of slow distal flow.