An algorithm has been designed for automatic detection of the endocardiac wall in the left ventricle based on ultrasonic images. The algorithm uses a closed polygon as an initial estimate of the cardiac wall. A set of search lines, normal to the initial estimate, are spaced uniformly around the initial polygon. An ellipse in the center of the image with search lines covering the entire image is used if no a-priori information is available. The wall is detected by computing the global optimum of all closed curves that can be drawn by selecting one point on each consecutive search line. The wall is optimal in terms of a functional that favors curves with a high radial gradient in the image intensity function, but disfavors curves that require a substantial geometrical deformation of the initial estimate. The fact that the wall represents a global optimum in terms of a functional makes it possible to prove theoretical properties of the computed wall. The part of the functional that measures geometry assures that the wall will preserve the form of the initial estimate in regions where the intensity function gives no indication of the location of the wall. This property is very useful because poor regional signal quality is a typical degradation in ultrasonic images.
"Automatic wall motion detection in the left ventricle using ultrasonic images", Proc. SPIE 1450, Biomedical Image Processing II, (1 July 1991); doi: 10.1117/12.44300; https://doi.org/10.1117/12.44300