A method and apparatus is provided for segmenting a left ventricular endocardium in a magnetic resonance image. Image shape, size, gradients, intensity, and connectivity are used to locate the endocardial boundary. Specifically, a series of dilations and refinements to a mask corresponding to acquired data is performed. Variations in intensity, representing the endocardial boundary, are detected, and the endocardial boundary may then be clearly identified in the MR image.