Articulated Whole-Body Atlases for Small Animal Image Analysis: Construction and Applications

Using three publicly available small-animal atlases (Sprague-Dawley rat, MOBY, and Digimouse), we built three articulated atlases and present several applications in the scope of molecular imaging. Major bones/bone groups were manually segmented for each atlas skeleton. Then, a kinematic model for each atlas was built: each joint position was identified and the corresponding degrees of freedom were specified. The articulated atlases enable automated registration into a common coordinate frame of multimodal small-animal imaging data. This eliminates the postural variability (e.g., of the head, back, and front limbs) that occurs in different time steps and due to modality differences and nonstandardized acquisition protocols. The articulated atlas proves to be a useful tool for multimodality image combination, follow-up studies, and image processing in the scope of molecular imaging. The proposed models were made publicly available.