Range-gated pulsed Doppler power frequency spectrum analysis for the diagnosis of carotid arterial occlusive disease.

Abstract

SUMMARY Carotid arterial disease was investigated with a Duplex Scanner using Power Frequency Spectrum Analysis. Sixty-one carotid systems were evaluated noninvasiveiy and angiographicalh, while 20 controls were examined and assumed to be normal. Peak frequency and 50% frequency bandwidth, a quantitative index of spectral broadening, were correlated with the percentage of stenosis. Peak frequency predicted the presence or absence of hemodynamfcally significant stenoses (>50% diameter reduction) with 90.8% accuracy, while 50% frequency bandwidth correctly identified similar lesions with 93.2% accuracy (p = NS). Also, with the latter results, carotid systems were grouped into <25%, 25% to 49%, and 2:50% stenosis categories with an 86.4% accuracy. Similar statistical evaluation was attempted for peak frequency results. It was not possible to separate hemodynamically insignificant lesions (<50% diameter reduction) into distinct groups because of the overlap of results among those arteries with <50% stenosis. Finally, all eight occluded internal carotid arteries were identified with combined Doppler/imaging analysis. However, with imaging alone, only 5 of 8 (63%) occluded arteries were correctly identified. Stroke Vol 17, No 5, 1986CAROTID ARTERIAL OCCLUSIVE DISEASE occurs most frequently in the carotid bifurcation, lending itself to easy detection by direct noninvasive ultrasonic techniques. Initially, bruit auscultation was the major physical finding that suggested carotid artery disease. 1 " 3 Next, continuous-wave ultrasonic evaluation provided significantly more information.6 " 10 Finally, the duplex scanner, combining simultaneous real-time B-mode ultrasonic imaging with pulsed Doppler spectrum analysis represented a further advance."" 23 Blackshear and colleagues" reported detection of 92% of all flow-limiting lesions (greater than 50%) in the internal carotid artery using the duplex scanner. Similar findings were reported by Fell and colleagues 13 and Doorly and co-workers. 23 However, these investigators, utilizing a subjective method of visually analyzing each Doppler velocity curve for spectral broadening, obtained less satisfactory results in detecting stenoses with less than 50% diameter reduction. In an effort to improve the detection of lesser degrees of disease, internal carotid artery to common carotid artery flow velocity (maximum and mean) ratios were examined.12 ' 18 ' M Use of these ratios improved the ability to detect hemodynamically insignificant lesions, but the data did not aid in quantitating the degree of stenosis.Recently, Krause and colleagues 24 applied power frequency spectrum analysis (PFSA) to carotid continuous-wave ultrasonic Doppler signals. The Doppler signals obtained during an 8-msec interval at peak systole were selected for further processing. Following frequency analysis, an amplitude versus frequency plot was obtained, and the bandwidth at 50% of peak From the

The correlation between the severity of peripheral arterial disease and carotid occlusive disease

“…These categories were based on standard image and flow criteria for the common, internal, and external carotid arteries. 33,34 Rather than smaller increments, 0-49% was used because the imaging studies did not consistently report stenosis less than 50%. Additionally, a stenosis of less than 50% is generally considered to be not hemodynamically significant.…”