Figure 1

Sample images illustrating the algorithmic steps for the automatic classification of partial-volume pixels and delineation of endocardial contour. Time-intensity (TI) profiles, which show the variation in intensity over time, were created for individual pixels along 8 radial lines centered on the centroid of the identified left ventricular region (a). Panel c shows zero-clamped TI profiles of the same pixels depicted in b, with the mean signal intensity over the cardiac cycle subtracted from the signal intensity at each time point.The convex hull was fitted to the thresholded images (blue corners of the polygon) (d). The curvature and spatial proximity to adjacent corner criterion were used to select the salient points (red dots) of the convex hull (e). A piecewise closed Bezier curve of second order geometric continuity was fitted through the salient points of the convex hull. The corresponding endocardial contours are shown in green for the end-diastolic (f) and end-systolic (g) phases.