The attenuation compensated C-mode flowmeter: a new Doppler method for blood volume flow measurement

Blood volume flow rate is a fundamental physiological parameter related to organ function. Its measurement using ultrasound, however, has not achieved widespread acceptance due to inaccuracy and difficulties of implementation. By replacing the conventional B-mode approach with a Doppler C-scan, the velocity orthogonal to a plane that transects the vessel is sampled, and can be integrated over an area larger than the lumen projection to yield the volume flow rate without the need to measure the Doppler angle or lumen area directly. However, this Doppler C-mode method suffers from partial volume error near the edge of the vessel. The authors address this problem by scaling each local mean velocity by the corresponding Doppler power before integration. Here, the authors present the basic theory and experimental investigation of this new technique of volume flow measurement. In vitro measurement of flow in a steady state flow phantom, using a mechanically scanned 5 MHz pulsed Doppler transducer, had a mean error of -10 mL/min, and an error distribution with a standard deviation of 17 mL/min for flow rates of 50-350 mL/min, and with Doppler angles of 50-70 degrees. These results are promising and suggest that the method is suitable for implementation in future on a real time 2D array system