An Ultrasonic Technique for Imaging the Ventricle in Three Dimensions and Calculating Its Volume

Real-time two-dimensional ultrasonic scanners provide a series of cross-sectional images of the ventricle. We have developed a technique which can determine the spatial position and orientation of a collection of such scans with respect to a reference coordinate system. The scans need not be parallel, may intersect, and need not demonstrate a complete cross section. The borders of interest are digitized to identify a set of points representing the surface of the ventricle. These points are used to generate a 3-D reconstruction of the chamber and are processed to give an estimate of ventricular volume. The technique has been validated using ten formalin-fixed hearts excised from dogs, sheep, and cows, with an actual volume range of 31.8-570.6 cm3. Each ventricle was imaged five times by three observers for a total of 150 studies. By the least squares linear regression analysis, calculated volume = 0.98 (actual volume) + 1.39 cm3, r = 0.99. The average error for all studies was 5 percent, while 88 percent of the individual calculated volume were within 10 percent of the actual volume. The method appears to offer the potential for the accurate assessment of ventricular volume in man.