1. A method for segmenting vertebrae in digitized images comprising the steps of: providing a plurality of digitized whole-body images, each said image comprising a plurality of intensities corresponding to a 3-dimensional (3D) grid of points; detecting and segmenting a spinal cord using a 3D polynomial spinal model in each of said plurality of images, wherein detecting and segmenting a spinal cord in an image comprises: splitting said image into a plurality of sampling bins; randomly selecting a subset of these bins; randomly selecting one sample point from each selected bin; computing coefficient vectors for said 3D polynomial spinal model evaluated at each selected sample point; computing, based on the coefficient vectors, extrema points for said 3D polynomial spinal model; and evaluating said 3D polynomial spinal model in a local neighborhood volume of bright points within a curved cylinder built around said polynomial, if said extrema points satisfy pre-defined constraints; finding a height of each vertebrae in each image from intensity projections along said spinal cord; and building a parametric model of a vertebrae from said plurality of images.