Accurate three-dimensional (3D) jet volume calculations would represent a major improvement in Doppler flow quantitation since two-dimensional color Doppler imaging has not been useful in this regard. However, the effects of color Doppler and 3D imaging settings on 3D volume calculations have not been studied. We imaged steady flow jets (30 cc/sec - 100 cc/sec)in vitro using a Toshiba scanner interfaced to a Tomtec 3D reconstruction computer, and calculated 3D spatial volumes, defined as the amount of space occuped by the jet within the receiving chamber, by summation of cross-sectional areas over the entire jet. We observed significant differences in calculated volumes due to color gain, 3D threshold, and color map. Wall filter and Nyquist limit also influence 3D volumes but only at low flow states (< 50 cc/sec). We obtained best correlation between 3D spatial volumes and actual flows at lowest color gain (1) and medium threshold level (63) (y = 2.1x - 0.86; r= 0.95). Our results should improve understanding of the effects of color Doppler and 3D reconstruction settings on 3D volume measurements and should aid in automating this technique for use in the clinical setting. Table

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