Volumetric blood flow measurement by simultaneous Doppler signal and B-mode image processing: a feasibility study

A system is described for the estimation of volumetric flow in arteries in real time by the simultaneous processing of the audio output of a commercial ultrasound scanner carrying the Doppler signal, and the video output carrying B-mode images of the lateral view of the artery. These images are processed to provide estimates of instantaneous internal vessel diameter. Combination with the relevant estimates of spatial mean velocity provides estimates of instantaneous volumetric flow. The major limitations of the system are the low rate of production of the B-mode images (17 Hz), the limited computing power and the need to tilt the transducer to produce an acceptably low Doppler angle. This tilting diminishes the quality of the imaging echoes from the arterial walls, making diameter measurement difficult. In principle, this approach to flow measurement represents an improvement on the conventional duplex technique where a single estimate of diameter is used. In practice, its value is limited by current transducer capabilities.