Volumetric blood flow measurement with the use of dynamic 3-dimensional ultrasound color flow imaging

We describe a new method for measuring blood volume flow with the use of fr eehand dynamic 3-dimensional echocardiography. During 10 to 20 cardiac cycl es, the ultrasonographic probe was slowly tilted while its spatial position was continuously recorded with a magnetic position sensor system. The ultr asonographic data were acquired In color flow imaging mode, and the separat e raw digital tissue and Doppler data were transferred to an external perso nal computer for postprocessing. From each time step in the reconstructed 3 -dimensional data, one cross-sectional slice was extracted with the measure d and recorded velocity vector components perpendicular to the slice. The v olume flow rate through these slices was found by integrating the velocity vector components, and was independent of the angle between the actual flow direction and the measured velocity vector. Allowing the extracted surface to move according to the movement of anatomic structures, an estimate of t he flow through the cardiac valves was achieved. The temporal resolution wa s preserved in the 3-dimensional reconstruction, and with a frame rate of u p to 104 frames/s, the reconstruction jitter artifacts were reduced. Exampl es of in vivo blood volume flow measurement are given, showing the possibil ities of measuring the cardiac output and analyzing blood flow velocity pro files.