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Low‐Velocity Flow Doppler Sonography

Doppler instrumentation incorporates filters to obtain meaningful data. Thus, flow Doppler can be used to analyze tissue or vice versa by complicated manipulations in settings. Factory-set "flow" or "tissue" modes in most machines make these transitions possible at the flick of a button. Flow Doppler sonography applies a high-pass filter to eliminate high-amplitude low-velocity tissue signals. In the process, some low-velocity flow signals may be lost. These low-velocity flow signals may be of clinical relevance. It has been hypothesized that tissue Doppler sonography may be used for the study of these low-velocity flow signals.1 On this basis, we have 2 types of flow Doppler techniques: (1) conventional flow Doppler or high-velocity flow Doppler (HVFD) and (2) tissue Doppler or low-velocity flow Doppler (LVFD). Low-velocity flow Doppler sonography can be in the form of color Doppler or pulsed wave Doppler imaging. These images are the documentation of a preliminary feasibility experiment to test the hypothesis in a clinical setting. No known case of tissue Doppler sonography used in flow studies has been reported previously. The study was done on a 45-year-old clinically healthy male volunteer. The LVFD recordings were obtained in the tissue Doppler mode on a Sonos 7500 machine (Philips Medical Systems, Andover, MA) using an s3 transducer from the apical 4-chamber view. The study was done in conformance with the principles of the Declaration of Helsinki.