PURPOSE: To evaluate and compare effectiveness of single acquisition CT and conventional angiography (CA) in grading stenosis in an artery of the lower extremity . MATERIALS AND METHODS: CA and CTA were performed in 12 patients with acclusive arterial disease of the lower extremity. CA extended from the bifurcation site of the abdominal aorta to the popliteal artery, 25-30 seconds after the injection of 120-150ml contrast media by a power injector at the rate of 2.5-3ml/sec via the antecubital vein. Using SSD and MIP methods, the data was reconstructed three-dimensionally. The artery was divided into five segments and the degree of lesion was definedas normal or mild (1-49%), moderate (50-74%), or severe stenosis (75-99%), or occlusion (100%). We retrospectively evaluated and compared the effectiveness of CTA and CA in the detection of each vessel and the grading ofstenosis. RESULTS: Although 11 segments were graded by CA as occluded, only five of these were similarly graded by CTA, and the remaining six were undergraded. The ratio of consistency for grading was 88.5% (46/52) in less thanmild stenosis, and 63.6% (7/11) in moderate or severe stenosis ; if the 11 segments detected only by CTA wereexcluded, the ratio of consistency for occlusion was 100%. Overall diagnostic accuracy was 84.2% (85/101) and whenthe 11 segments were excluded, this was 88.9% (80/90). Because of the capacity of CTA to distinguish vessles with greater than 50% stenosis from those with less than mild stenosis, sensitivity of 86.0%, specificity of 93.2% and accuracy of 89.1% were recorded. If the 11 vessels detected only by CTA were excluded, sensitivity and accuracy would be 91.3% and 92.2%, respectively. CONCLUSION: For detecting and grading stenosis in an artery of the lowerextremity, single acquisition CTA is more accurate than its conventional counter part, and we believe that CTA is a useful modality in the planning and follow-up of treatment.