14. The apparatus of claim 13 , wherein the statistical shape model of the prostate represents the shape of the prostate as a linear combination of a mean prostate shape and a number of strongest shape modes each weighted by a respective shape coefficient.
15. The apparatus of claim 14 , wherein the means for obtaining the initial prostate segmentation in the MR image by aligning the learned statistical shape model of the prostate to the MR image using marginal space learning (MSL) comprises: means for detecting position candidates for the prostate in the MR image using a first discriminative classifier; means for detecting position-orientation candidates for the prostate in the MR image based on the detected position candidates using a second discriminative classifier; means for detecting position-orientation-scale candidates for the prostate in the MR image based on the detected position-orientation candidates using a third discriminative classifier, wherein each position-orientation-scale candidate defines a candidate bounding box for aligning the mean prostate shape to the MR image; and means for detecting the respective shape coefficient for each of the number of strongest shape modes based on the detected position-orientation-scale candidates using a fourth discriminative classifier.