3-DIMENSIONAL RECONSTRUCTION OF COLOR DOPPLER FLOW CONVERGENCE REGIONS AND REGURGITANT JETS - AN IN-VITRO QUANTITATIVE STUDY

Objectives. This study sought to investigate the applicability of a cu rrent implementation of a three-dimensional echocardiographic reconstr uction method for color Doppler how convergence and regurgitant jet im aging. Background. Evaluation of regurgitant flow events, such as flow convergences or regurgitant jets, using two dimensional imaging ultra sound color flow Doppler systems may not be robust enough to character ize these spatially complex events. Methods. We studied two in vitro m odels using steady flow to optimize results. In the first constant-flo w model, two different orifices were each mounted to produce flow conv ergences and free jets-a circular orifice and a rectangular orifice wi th orifice area of 0.24 cm(2). In another flow model, steady hows thro ugh a circular orifice were directed toward a curved surrounding wall to produce wall adherent jets. Video composite data of color Doppler f low images from both free jet and wall jet models were reconstructed a nd analyzed after computer-controlled 180 degrees rotational acquisiti on using a TomTec computer. Results. For the free jet model there was an excellent relation between actual flow rates and three dimensional regurgitant jet volumes for both circular and rectangular orifices (r = 0.99 and r = 0.98, respectively). However, the rectangular orifice p roduced larger jet volumes than the circular orifice, even at the same how rates (p < 0.0001). Calculated flow rates by the hemispheric mode l using one axial measurement of the pow convergence isovelocity surfa ce from two-dimensional color flow images underestimated actual flow r ate by 35% for the circular orifice and by 44% for the rectangular ori fice, whereas a hemielliptic method implemented using three axial meas urements of the flow convergence zone derived using three-dimensional reconstruction correlated well with and underestimated actual flow rat e to a lesser degree (22% for the circular orifice, 32% for the rectan gular orifice). In the wall jet model, the jets were flattened against and spread along the wall and had reduced regurgitant jet volumes com pared with free jets (p < 0.01). Conclusions. Three-dimensional recons truction of flow imaged by color Doppler may add quantitative spatial information to aid computation methods that have been used for evaluat ing valvular regurgitation, especially where they relate to complex ge ometric flow events.