Figure 3c. Sagittal power Doppler US images show the effects of stepwise changes in gain on both feeding and stenotic vessels with the high-frequency transducer. Baseline settings are as follows: longitudinal view; insonation angle, 60°; peak systolic velocity, 1 m/sec; pulse repetition frequency, 1,500 Hz; filter, low; and color versus echo priority, 100%. Gain is increased from (a) 20% to (b) 40% and (c) 60%, which results in increasing apparent lumen of the stenotic and normal vessels from 0.30 and 0.65 cm to 0.36 and 0.79 cm and 0.53 and 0.93 cm, respectively.