Volumetric blood flow assessment through multigate spectral Doppler

Volumetric blood flow measurements require the assessment of both the velocity distribution and the cross-sectional area of the vessel. Unfortunately several difficulties hamper such a measurement in standard approaches. A new dual beam method has been recently introduced in which the Doppler spectral symmetry is exploited to finely orientating the first beam at 90° with respect to the flow, so that the remaining beam can perform a velocity measurement with known Doppler angle. In this paper it is shown how this special beam configuration proves particularly suitable for volume flow measurements. While the transverse beam performs a diameter measurement with optimal orientation, the velocity distribution along the second beam is measured through multigate spectral analysis. The method has been coded on a research system. In-vitro experiments produced a bias less then 7% with a coefficient of variability (CV) less then 5%. In preliminary tests on 3 volunteers CVs within 10% were obtained.