Dynamic ultrasonic visualization of blood vessels and flows

This paper describes a new method for dynamic real-time visualization of blood flows. This method uses a special signal processing system (SEC) which consists in cancellation of stationary echoes from the reflections of ultrasonic waves from soft tissues with continuous measurement of the phase of signals scat¬tered in blood.
The stationary echo cancellation system has been designed on the basis of the properties of periodic filters using quartz delay lines. A level of stationary echo cancellation above 55 dB was achieved, which, when using an original detector of the phase of signals scattered in blood, permits real-time observation of blood flow velocity profiles. This, in turn, permits the internal diameter of a vessel (the degree of constriction) to be evaluated in the site under investi¬gation.