Duplex scanning for diagnosis of aortoiliac and femoropopliteal disease: a prospective study.

We compared ultrasonic duplex scanning and angiography for the localization and classification of arterial stenoses and occlusions in 32 patients. The criteria for the detection of a greater than 50% diameter reducing stenosis was an increase in peak systolic velocity of greater than 100%, loss of reverse flow, and spectral broadening. Duplex studies and angiograms were evaluated in a blinded fashion. The agreement between duplex scanning and angiography for the 383 arterial segments studied was not significantly different than the previously reported agreement between two different radiologists reading the same angiograms (kappa of 0.55 vs 0.63). For detecting stenoses that were greater than 50% diameter reducing by angiography, duplex scanning had a sensitivity of 82%, a specificity of 92%, a positive predictive value of 80%, and a negative predictive value of 93%. These results are as good as previously reported comparisons between two different radiologists' readings of the same angiograms.