Doppler US: the basics.

Doppler ultrasonography (US) is an invaluable tool in the diagnosis of occlusive vascular disease and is assuming increasing importance in the diagnosis of abdominal, pelvic, and fetal disorders. The author presents for new users the basic physics principles of Doppler US in his discussions of the Doppler principle, instrumentation, signal processing and display, artifacts, and interpretation of data. An understanding of these principles will assist radiologists in using the full potential of Doppler US in the diagnostic workup.