1. A method for detecting and labeling intervertebral disks in a 3D image, comprising: detecting a plurality of intervertebral disk candidates in the 3D image using iterative marginal space learning, wherein a first one of a plurality of iterations of the iterative marginal space learning detects a shared set of initial position candidates and each subsequent one of the plurality of iterations of the iterative marginal space learning removes position candidates close to detected intervertebral disk candidates from the shared set of initial position candidates and selects a number of most likely position candidates from position candidates remaining in the shared set of initial position candidates; and selecting a separate one of the plurality of intervertebral disk candidates for each of a plurality of labeled intervertebral disk locations using a probabilistic spine model.