Noninvasive measurement of blood flow rate utilizing ultrasound

摘要

In order to perform a non-invasive measurement of the blood flow rate in the smallest vessels, i.e. the capillaries, of a blood vessel bed, and to detect the presence of erythrocyte aggregations therein, acoustic pulses containing oscillations at a frequency above 20 MHz are directed through the skin of a subject from a crystal transducer and the resulting echo pulses are processed to produce information based on the Doppler frequency signals relating to blood flow in a predetermined direction and occurring within a time window corresponding to the distance from the crystal of the blood vessels to be examined. Interspersed between the above-mentioned pulses, spike pulses having a duration of the order of 20 ns are similarly transmitted, and echoes thereof are detected for the purpose of detecting the presence of erythrocyte aggregations.