DUPLEX VELOCITY CHARACTERISTICS OF AORTOILIAC STENOSES

Purpose: It is now possible to grade aortoiliac stenoses in broad cate gories based on peak systolic velocity (PSV) changes. The goal of this study was to see whether additional simple Doppler parameters would i mprove the grading of aortoiliac obstructive disease. Methods: Duplex parameters were compared in 112 aortoiliac segments with four categori es of arteriographic diameter reduction and four categories of common femoral artery pressure measurements. These parameters were PSV, PSV r atio, PSV difference, end diastolic velocity (EDV), the presence or ab sence of reverse flong and the presence or absence of spectral broaden ing. Results: The discriminative value of the PSV ratio was better tha n that of either the absolute PSV value or the PSV difference. A PSV r atio <1.5 combined with reverse flow and a clear systolic window in th e Doppler spectrum predicted a diameter reduction <20% (sensitivity, 1 00%; specificity, 58%; positive predictive value [PPV], 89%; negative predictive value [NPV], 100%; accuracy, 90%). For the detection of gre ater than or equal to 50% aortoiliac stenoses, a PSV ratio greater tha n or equal to 2.8 provided 86% sensitivity and 84% specificity (PPV, 8 4%; NPV, 85%, accuracy, 85%). An absolute PSV value of 200 cm/sec has a high sensitivity (95%) but a low specificity (55%) in identifying gr eater than or equal to 50% stenoses (PPV, 68%; NPV, 91%; accuracy 75%) . An EDV >0 cm/sec at the stenosis indicates a femorobrachial pressure index <0.90 with 51% sensitivity and 89% specificity. An EDV greater than or equal to 40 cm/sec indicates a femorobrachial index <0.80 with 50% sensitivity and 89% specificity, and indicates greater than or eq ual to 75% arteriographic stenoses with 70% sensitivity and 90% specif icity (PPV, 64%; NPV, 92%; accuracy, 86%). A stenosis greater than or equal to 75% was also identified by a PSV ratio of 5.0 with 65% sensit ivity and 91% specificity (PPV, 65%; NPV, 91%; accuracy, 86%). Conclus ions: The PSV ratio is the most important parameter to grade aortoilia c stenoses into <20%, 20% to 49%, 50% to 74%, and 75% to 99% categorie s, but additional parameters such as absolute PSV value, EDV, and the presence or absence of reverse flow and spectral broadening in the Dop pler spectrum are helpful in gradation.