Quadrature matched filters in image analysis of echocardiograms

Twelve echocardiograms of the left ventricle are processed with a 2-D radial quadrature matched filter to identify endocardial border locations and orientations. Orientation angles of border edges, obtained from the quadrature output signals, exhibit gradual changes around the border. Using 3-pixel-wide edge models, a change in angle of less than 3° is found between 70.3% of the adjacent pairs of border points. The results show that gradual changes in angle are an excellent means for border identification