A method for refining shape estimates of detected abnormalities in medical images, particularly for the detection of pulmonary lesions in CT imagery is described. A cue point is refined prior to an initially segmentation of the lesion. A radial gradient is computed for points on an initial segmented lesion. Portions of the lesion with radial gradients deviating beyond a threshold angle are removed from the lesion. Registering imagery from more than one CT exam uses a high intensity structure, essentially bone, to provide coarse and fine alignment of a set of two-dimensional images is also described. A MIP image is formed from the three-dimensional images. A second MIP image is then formed from imagery. The second MIP image is correlated with the first MIP image to determine a preferred registration location.