1. A computed tomography (CT) method comprising: receiving CT scan image data representative of a portion of a body and an indication of a seed point within a nodule in a CT scan image of the portion of the body; performing by computation using a computing device fine segmentation based on local contrast of the CT scan image, to separate foreground areas from background areas of the CT scan image; defining by computation from the CT scan image a mask including an object containing the seed point, connected foreground area, and background area surrounding the object, and excluding other foreground objects; computing the connectivity of points of the CT scan image to the seed point; and applying by computation a selective criterion to the connectivity of the points of the CT scan image to determine the extent of the nodule in the CT scan image, wherein the mask limits the determined extent of the nodule in the CT scan image.