Quantitative assessment of regurgitant flow with total digital three-dimensional reconstruction of color Doppler flow in the convergent region: in vitro validation.

BACKGROUND: This study was designed to develop and test a total digital 3-dimensional (3D) color flow map reconstruction for proximal isovelocity surface area (PISA) measurement in the convergent region.

METHODS: Asymmetric flow convergent velocity field was created in an in vitro pulsatile model of mitral regurgitation. Image files stored in the echocardiographic scanner memory were digitally transferred to a computer workstation, and custom software decoded the file format, extracted velocity information, and generated 3D flow images automatically. PISA and volume flow rate were calculated without geometric assumption. For comparison, regurgitant volume was also calculated, using continuous wave Doppler, 2-dimensional (2D), and M-mode color flow Doppler with the hemispheric approach.

RESULTS: Flows from 3D digital velocity profiles showed a closed, excellent relation with actual flow rates, especially for instantaneous flow rate. Regurgitant volume calculated with the 3D method underestimated the actual flow rate by 2.6%, whereas 2D and the M-mode method show greater underestimation (44.2% and 32.1%, respectively).

CONCLUSION: Our 3D reconstruction of color flow Doppler images gives more exact information of the flow convergent zone, especially in complex geometric flow fields. Its total digital velocity process allows accurate measurement of convergent surface area and improves quantitation of valvular regurgitation.