1. A method for analyzing a shape of a region of interest in a medical image of a body part, comprising: collecting, by a scanner, the medical image of the body part; finding, by a processor, a region of interest in the medical image; calculating, by the processor, a Reeb graph of the region of interest; and determining, by the processor, whether the region of interest is a malignant lesion candidate based on a shape characteristic of the Reeb graph.