Cyclic variation of the power of ultrasonic Doppler signal from pulsatile blood flow

Doppler ultrasound has been used as a clinical tool for measuring the velocity of blood flow in vessels for many years. The power of the ultrasonic Doppler signal from blood is related to blood properties and flow conditions i.e., hematocrit, nature of flow, degree of cell aggregation, etc. and has recently been used to obtain the so-called “power mode” Doppler images. It would help one to interpret the image if one understood how it changes in response to different conditions. The variation of the power of the ultrasonic Doppler signal from porcine blood during the flow cycle under pulsatile flow conditions has been evaluated experimentally with a 10 MHz pulsed Doppler flowmeter using a pulsatile flow mock loop consisting of a polystyrene or latex vessel model at a peak flow rate of 0.6188 l/min (30 to 60 beats/min), similar to physiological conditions, but of different stroke rates. A significant difference in the cyclic variation of Doppler power is observed as the stroke rate or measuring site is varied