Quantification of Valvular Regurgitation Area and Geometry using HPRF 3D Doppler

It is important to accurately determine the severity of valvular regurgitation as surgery is indicated only in severe regurgitations. The evaluation of, for example, mitral regurgitation is complex and the current methods have limitations. We have developed a 3D ultrasound Doppler method to estimate the cross-sectional area and the geometry of a regurgitant jet at the vena contracta just downstream from the actual orifice. The back-scattered Doppler signal from multiple beams distributed over the area of interest was measured. The received power from these beams were then calibrated using both a-priori knowledge of the lateral extent of the beams and a reference beam which was completely enclosed by the vena contracta. The method has been implemented and verified by computer simulations and by in-vitro experiments using a pulsatile flow phantom and prosthetic valves with a range of holes. We were able to distinguish between mild, moderate and severe valvular regurgitation and also quantify the regurgitational area as well as showing the geometry of the regurgitation.