Measurement of volumetric flow with no angle correction using multiplanar pulsed Doppler ultrasound

The authors show that by scanning at points on the surface of a sphere that the normal angle correction used in pulsed Doppler flow measurements is no longer necessary. Thus, it is possible to measure three-dimensional (3-D) flow using multiplanar ultrasound even though one only gets one-dimensional (1-D) velocity information from pulsed Doppler ultrasound. The technique handles the three basic problems in flow measurements using ultrasound Doppler: the variations of the cross-sectional area; the time-dependent changes in the velocity field; and the dependency of the angle of insonation. The technique is tested in a flow phantom using different angles of insonation to validate the angle independence of this new technique. Using six different angles of insonation in the range 0° to 69° with flow rates in the range of 0-170 ml/s a linear dependence was found to be: measured (color Doppler)=0.98 real flow (reference) +1.36 ml/s, with a 95% confidence interval of ±13.9 ml/s.