Power Doppler US: Evaluation of the Morphology of Stenoses with a Flow Phantom

PURPOSE: To determine the importance of technical settings at power Doppler ultrasonography (US) for the evaluation of stenoses. MATERIALS AND METHODS: A computer-controlled phantom was used to induce a reproducible flow across a calibrated 71% stenosis in an 8.4-mm-diameter tube. Two transducers, 2–4 and 5–10 MHz, working at depths of 3.0 and 11.5 cm, respectively, with different beam angles (40°, 60°, and 90°), were used to simulate evaluation of pulsatile flow across normal and stenotic vessels in various conditions. For each condition, gain, pulse repetition frequency, and wall filter were progressively turned from low to high values. Two observers measured in a blinded fashion the apparent lumen of the stenotic and normal vessels on longitudinal and transverse images with the use of power Doppler US. RESULTS: When the high-frequency transducer was used, gain significantly affected both stenotic and feeding vessel measurement, whereas pulse repetition frequency and filter only affected feeding vessel ...