FREMGANGSMAATE OG APPARAT VED BLODSTROEM-HASTIGHETSMAALING MED ULTRALYD FOR DANNELSE AV TODIMENSJONAL AVBILDNING AV BLODETS HASTIGHET

摘要

Method and apparatus for generating a multidimensional map of blood velocities in the circulatory system of living species, using the Doppler effect of backscattered ultrasound from the blood, with real time presentation on a display device, with the ability to select small sample volumes in the flow map where the information can be presented as a function of time together with the moving multidimensional map in real time. There is transmitted a pulsed ultrasonic beam which is swept in two or more dimensions through the region of the biological structure which is to be investigated. The backscattered ultrasonic signal is sampled in a number of depth volumes along each beam direction of the transmitted ultrasonic pulses. For each depth and beam direction there is determined a velocity parameter of the blood flow by means of the Doppler principle, and the velocity parameters from the whole region investigated are read into an image memory. Therefrom they are read out repeatedly for coded presentation on the display screen. By synthesizing on the basis of the backscattered signal from one or more selected sample volumes in the region investigated, there is generated an estimate signal to substitute the missing Doppler signal in these sample volumes while there is measured in other directions, for determining the frequency spectrum of the signal or a frequency parameter thereof, for example maximum frequency, which is simultaneously displayed as a function of time. The main use of the invention is for medical diagnosis, in particular in hospitals.