Computerized evaluation of blood flow measurement indices using Doppler ultrasound

The study involved computer-assisted analysis of Doppler blood flow signals from an in vitro experimental system utilizing a calibrated occlusive pulsatile pump, vinyl tubings of various dimensions, and human blood. The power spectra of these signals were obtained using the Fast Fourier Transform, and the peak and mean frequencies along with the first moments of the Fourier spectra around the zero-frequency axis were computed. These indices were evaluated using different flow rates and tubal dimensions. It was experimentally verified that the first moment provided a more linear measure of volume flow rate than that estimated by peak and mean velocities. Although the first moment cannot measure the absolute flow rate, it may serve as a better indicator of relative flow changes than the other two indices.