Quantitative Dual-beam Doppler Ultrasound Investigations

The lack of knowledge of the beam-flow angle represents one of the major sources of uncertainty in Doppler measurements. Not only are some new, appealing applications of the Doppler technique prevented, but some basic clinical procedures are made more difficult than desirable. This paper reports on the Doppler angle ambiguity problem and on the classic solutions so far proposed in order to overcome the related limitations. The main features of a recently introduced dual-beam method are described. Starting from the classic problem of measuring the true velocity in a single sample volume, the application to the measurement of full velocity profiles is discussed. Combination of this method with a new multi-channel multi-gate system is shown capable of contributing to arterial mechanics investigations by allowing the simultaneous measurement of wall shear rate and wall distension in major human arteries. Finally the feasibility of accurate volumetric flow measurements is discussed, and work-in-progress is reported.