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A triple-beam lens transducer provides reasonably accurate estimation of the 3-D flow velocity vector of flowing blood. The measured peak flow velocity is in agreement with theoretical value to within 15%. The measured mean lateral angles and the mean lateral angles agree to within plus or minus 15 and 5 degrees, respectively. The experimental results obtained using a prototype system are discussed.

The estimation of the 3-D flow velocity vector of blood with ultrasound triple-beam lens transducers is reported. The lens acts to direct and focus the ultrasound from the elements such that three parallel, closely spaced ultrasound beams are produced. Comparison of aluminum and quartz lenses suggests that both materials generates beam characteristics with similar accuracies compared with theory, and that aluminum lenses displayed superior performances in terms of bandwidths.

The validation of the ultrasound time-domain correlation method of measuring blood flow has required the development of a flexible blood flow phantom capable of generating predictable flow profiles under a wide variety of conditions. The purpose of the phantom is to generate flow with well-known flow properties and not to mimic actual in vivo vessels. This paper describes a flow phantom which can independently generate both constant and pulsatile flow over a wide range of flow rates with a spatially fully developed laminar flow profile. It incorporates a computer-controlled pulsatile pump, which can produce different temporal pulsatile waveforms. The flow phantom also supports multiple vessels, different vessel sizes, as well as different attenuating media. The fluid most commonly used in the phantom is Sephadex mixed with water, and the probability density function of ultrasound reflected from Sephadex is experimentally determined and compared with that of blood. Examples of different constant and pulsatile flow experiments using the phantom are presented.