Automatic left ventricular endocardium detection in echocardiograms based on ternary thresholding method

Methods for automatic detection of left ventricular endocardium in echocardiograms are required to quantitatively evaluate the functional performance of the left ventricle. This study proposes a new automatic detection method based on ternary thresholding method for echocardiograms. Two thresholds are determined by the discriminant analysis for the gray level histogram so that the input image is segmented into three regions, i.e. cardiac cavity (black region), near epicardium (white region) , and the rest (gray region). Then the input echocardiogram is binarized with the lower threshold (between black and gray) to detect the cardiac cavity. The binary images are contracted n times to remove small regions and to disconnect the region of cardiac cavity from the other false regions. Among the obtained regions which corresponds to the cardiac cavity is selected and dilated 2n times to create a mask which restricts the region of the second thresholding operation. The masked image of each frame is binarized with another threshold determined by the discriminant analysis in the restricted area. Results of the evaluation test showed that the accuracy of the extracted contours was favorably compared with the accuracy of manually traced contours.