Methods for discriminating flow direction with continuous wave Doppler equipment

Ultraschall in der Medizin : Organ der Deutschen Gesellschaft für Ultraschall in der Medizin, [der] Österreichischen Gesellschaft für Ultraschall in der Medizin, [der] Schweizerischen Gesellschaft für Ultraschall in Medizin und Biologie
H Dudwiesus, M J Teague

Abstract

The application of ultrasound Doppler units for the localization of incompetent venous valves, the examination of extracranial vessels, and the evaluation of the hemodynamic effect of certain cardiac dysfunctions requires directional models with the possibility of recording Doppler wave forms. Various techniques are used to determine flow direction all of them presenting specific advantages and disadvantages in practical use. After briefly explaining the basic Doppler technique, the three most commonly used methods, the two-channel filter technique, the McLeod system, and the outphaser system, are described. The characteristics of the various signal processing techniques are discussed, particularly in the case of complex hemodynamic conditions.

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