Relationship between Doppler pulsatility index and direct femoral pressure measurements in the diagnosis of aortoiliac occlusive disease.

One hundred and seventy-five aortofemoral segments were studied in order to determine the role of CW Doppler ultrasound combined with real-time spectral analysis in the assessment of aortoiliac disease. The pulsatility index (PI), determined from the maximum velocity waveform, was compared to the systolic pressure difference between the aorta and common-femoral artery as measured at the time of angiography. Receiver operating characteristic curves were constructed and the optimum sensitivities and specificities measured. Results show that if a PI(max) of 5.5 is taken as the threshold level, then the PI is 95% sensitive and specific in detecting hemodynamically significant aortoiliac disease that corresponds to a resting aortofemoral pressure difference of 10 mm Hg or greater. We also carefully examine those technical aspects of Doppler recording and analysis that influence the accuracy of PI measurements.