A method and system for image processing are provided. An MR image including a plurality of slice images may be obtained. The plurality of slice images including a myocardium of a left ventricle. A reference image for each slice image of the plurality of slice images may be determined. An endocardial boundary of the myocardium for the each slice image of the plurality of slice images may be determined. The each slice image of the plurality of slice images may be registered according to a corresponding reference image. An epicardial boundary of the myocardium in the each slice image of the plurality of slice images may be determined according to the endocardial boundary of the myocardium in the registered each slice image of the plurality of slice images.