Vector field interpolation for cardiac motion compensated reconstruction

Cardiac CT image reconstruction suffers from motion artifacts due to heart motion during acquisition. In order to mitigate these effects, it is common practice to acquire with fast gantry rotation and do gated reconstruction. In addition, it is possible to estimate heart motion retrospectively and to incorporate that information in a motion compensated reconstruction (MCR). However, if shape tracking algorithms are used for generation of a heart motion vector field (MVF), the number and positions of the resulting motion vectors will not coincide with the number and positions of the voxels in the reconstruction grid. For MCR algorithms that require one motion vector at each voxel location, the MVF must be interpolated. This work examines different interpolation approaches for the MVF interpolation problem and their effects on the MCR results.