Volumetric Blood Flow via Time-Domain Correlation: Experimental Verification

A new ultrasonic volumetric flow measurement method employing time-domain correlation of consecutive pairs of echoes has been developed. An ultrasonic data acquisition system determined the lime shift between a pair of range gated echoes by searching for the time shift with the maximum correlation between the RF sampled waveforms. Experiments with a 5-MHz transducer indicate that the standard deviation of the estimate of steady fluid velocity through 6-mm diameter tubes is less than 10% of the mean. Experimentally, Sephadex (G-50; 20-80 urn dia.) particles in water and fresh porcine blood have been used as ultrasound scattering fluids. Two-dimensional (2-D) flow velocity can be estimated by slowly sweeping the ultrasonic beam across the blood vessel phantom. Volumetric flow through the vessel is estimated by integrating the 2-D flow velocity field and further is compared to hydrodynamic flow measurements to assess the overall experimental accuracy of the time domain method. Flow rates from 50-500 ml/min have been estimated with an accuracy better than 10% under the idealized characteristics employed in this study such as straight circular thin-walled tubes, laminar axially symmetric, steady flow, and no intervening tissue.