A new 3-D reconstruction method for 2-D echocardiograms is described. An orthogonal 2-D echocardiography is used to take two sectional cardiac ultrasound images simultaneously. Ninety images (ten phases of the cardiac cycle × (one long axis image + eight short axis images)) are digitized for preprocessing and 3-D processing.

The basic aim of the paper is to present a method for boundary-line extraction from long axis images and short axis images. Sixteen directions are used. At first, up, down, right, and left boundary points are detected by a differential filter of size 7 × 2 and separation 1. Every unvisited direction (the neighboring direction, the symmetric direction with respect to the vertical line, and the symmetric direction with respect to the horizontal line) is checked in the order given.

A boundary point is located at the same distance from the center and is checked with a differential filter. For every five points on a line segment (of a polygon boundary) a finer boundary point is found along a line perpendicular to the segment, using a differential filter of size 5 × 1 and separation 1. For boundary-line extraction from short axis images, consider long axis boundary lines. Two vertical and two horizontal reference boundary points of short axis images are obtained. The shape of the short axis boundary line is approximated by an ellipse that passes through the four boundary points. Repeating these steps for all images, a 3-D wire frame shape with motion of the left ventricle can be obtained.

The stated aim is thoroughly fulfilled. The volume curve is also calculated. Some information about errors is given, but nothing is said about the increase in complexity for a large number of directions.

The reader needs no special background. The references are good. Some typographical mistakes appear in the text.