Doppler developments in the last quinquennium.

The major advances which have taken place during the last five years in the development of ultrasonic Doppler devices and methods of Doppler signal analysis are reviewed. The following aspects of instrumentation are considered: crossed beam Doppler systems, range measuring Doppler systems, duplex systems, flow mapping systems, transducers and measurements of system performance. Analytical methods are discussed in the following categories: waveform analysis, including the extraction of single-value waveforms and their applications to the diagnosis of vascular disease; spectral analysis, including the derivation of frequency spectra and their application in the study of blood flow; and volume flow estimation. It is concluded that it is likely to be in the study of the information in Doppler frequency spectra, two-dimensional real-time Doppler images and in the measurement of blood flow volume that most progress will be made.