Adjustment of color gain with color flow US as the active scanning mode. (a, b) Color Doppler flow US images obtained with a gain setting of 44% (a) and 100% (b) show underadjustment and overadjustment, respectively. (c) Color Doppler flow US image obtained with an optimal gain setting of 65% demonstrates normal-appearing wall-to-wall flow in the main portal vein. Note that, although the color gain changes, no change occurs in the color velocity scale (23 cm/sec) or sampling rate (PRF = 1,500 Hz).

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