Quantitative analysis of carotid artery Doppler spectral waveforms: diagnostic value of parameters.

Continuous-wave ultrasonic Doppler recordings made at the carotid bifurcation have been processed by spectrum analysis and off-line microprocessor software. Data reduction algorithms were defined and tested prior to incorporation in an integrated, hard-wired device. Subsequent analysis of waveforms in real-time provided measures of peak and mode frequencies and degree of spectral broadening. Correlation of results with 123 angiographically visualized internal carotid arteries showed that peak and mode frequencies generally increased with degree of stenosis while the systolic window decreased. Ratios of peak and mode frequencies in the proximal to the distal internal carotid artery and the systolic window at the distal internal carotid artery were retrospectively found to have diagnostic value with a combination of these three parameters providing the best overall accuracy.