1. A method of detecting a candidate abnormality in a sonographic medical image, comprising the steps of: obtaining a sonographic medical image; determining a radial gradient index (RGI) at plural pixels to produce an RGI image; thresholding the RGI image; determining a candidate abnormality in the RGI image based on the thresholding step; and locating a center point of the candidate abnormality in the RGI image and a corresponding center point in the sonographic image.