Blood flow velocity measurements: a comparison of 25 clinical ultrasonographic units.

A blood-mimicking flow phantom was used to evaluate the precision of velocity measurements acquired using 25 pulsed Doppler ultrasonographic units from four vendors. Measurements were made at four constant flow rates (12 to 50 cm/s peak velocity). The average standard deviation values of the peak and time-averaged velocities among all units and all flow rates were found to be 7 and 9% of the mean, respectively, while the corresponding values for a subgroup of 20 identical units were 5 and 8%. Considered in conjunction with other published data, this suggests that units should be calibrated to an institutional standard at the time of acceptance testing.