An automatic contour extraction algorithm for short-axis cardiac magnetic resonance images.

In this article an automatic process is presented for the extraction of the left ventricular contours. The only operator-supplied information is the location of a single point within the left ventricle. The raw data for processing are short-axis cardiac MR images, obtained using various MRI protocols. In this study we considered only protocols for which the blood appears dark. The proposed algorithm performs smoothing and thresholding of the original MR images, and uses the segmented images to form edge images. From those edge images the endocardial curve is extracted using a modified contour following approach. The algorithm can accommodate moderate noise and small gaps in the contour. A smooth curve that approximates the epicardium is then obtained using a method combining radial search and FFT based smoothing. The quality of the obtained contours was visually assessed by three observers. Their evaluation shows that the algorithm is successful when images of reasonable quality are processed. Further evaluation work is required in order to fully assess the performance and limitation of the suggested method.