Evaluation of the peak frequency ratio (PFR) measurement in the detection of internal carotid artery stenosis.

The peak frequency ratio (PFR) between the internal carotid and common carotid artery Fast Fourier Transform Spectral Analysis patterns has been used to identify patients with internal carotid artery stenosis. To evaluate further the accuracy of the PFR, we applied it to the spectral analysis data from 396 vessels whose sound signals were obtained with a Duplex scanner (pulsed Doppler) and 246 arteries whose audible flow data were generated by a continuous-wave Doppler. The pulse Doppler with spectral analysis (PD/SA) correctly identified 221/254 (87%) of the vessels with less than 50% angiographic stenosis, 81/100 (81%) of the arteries with 50-99% stenosis, and 35/42 (83%) of the totally occluded internal carotid vessels for an overall accuracy of 85%. The continuous-wave Doppler with spectral analysis (CW/SA) did well in two categories but had an unacceptably high 47% false-negative rate for arteries with 50-99% stenosis. The PFR when applied to PD/SA test results is a useful parameter in screening patients with suspected internal carotid artery stenosis.