Measurement of blood flow using Doppler-shifted ultrasound

Abstract

Ultrasonic fields can be used to measure the complex dynamic flow patterns in a wide range of intact blood vessels with calibres ranging from fractions of a millimetre to several centimetres. Many of these vessels may be examined non-invasively from outside the body. Ultrasonic flowmeters have developed from the early transit-time instruments through the continuous-wave Doppler velocimeters to the complex multigate pulsed Doppler and conposite duplex B-mode/pulsed Doppler imaging systems which are capable of measuring true volume flowrates. The natural constraints associated with the fundamental methods, the various techniques, and the signal-processing stages are all considered in relation to the quantitative measurement of blood-flow velocity and volume flow rate with particular reference to potential sources of error.