Adaptive non-rigid registration of 3D knee MRI in different pose spaces

Volume registration of articulated subjects such as the human knee region requires novel methods to accommodate the wide range of movement resulting from skeletal joint rotations. This paper addresses articulated volume deformation with a pair of techniques. Volume skeletal deformation (VSD) is applied first, producing a smooth but approximate deformation of the soft tissue as the underlying skeleton moves, while preserving rigid motion in the segmented bone regions. The resulting deformed volume is used as initialization for a non- rigid deformation step that locally and adaptively adds radial basis function control points to minimize the remaining registration error in any poorly aligned region. The resulting process registers a neutral pose volume to any given bent-knee pose MRI scan.