“…In [2], a clever search is performed based on prior information through the candidates, while [1,4,5] fit a low order polynomial curve to the candidates to remove outliers. In [3,6,8,9] the authors add prior information via graphical models, such as Hidden Markov Models (HMMs) [10], and infer the maximum a-posteriori (MAP) estimate for the vertebrae locations. In contrast, [11,12] use a fully generative model, and inference is achieved via generalized expectation-maximization, while in [7] deformable templates are used for segmentation and subsequent identification.…”