Estimate, Compensate, Iterate: Joint Motion Estimation and Compensation in 4-D Cardiac C-arm Computed Tomography

C-arm computed tomography reconstruction of multiple cardiac phases could provide a highly useful tool to interventional cardiologists in the catheter laboratory. Today, however, for clinically reasonable acquisition protocols the achievable image quality is still severely limited due to undersampling artifacts. We propose an iterative optimization scheme combining image registration, motion compensation and spatiotemporal regularization to improve upon the state-of-the-art w. r. t. image quality and accuracy of motion estimation. Evaluation of clinical cases indicates an improved visual appearance and temporal consistency, evidenced by a strong decrease in temporal variance in uncontrasted regions accompanied by an increased sharpness of the contrasted left ventricular blood pool boundary. In a phantom study, the universal image quality index proposed by Wang et al. is raised from 0.80 to 0.95, with 1.0 corresponding to a perfect match with the ground truth. The results lay a promising foundation for interventional cardiac functional analysis.