Registration of a Cardiac Motion Model to Video for Augmented Reality Image Guidance of Coronary Artery Bypass

The aim of the work described in this paper is registration of a 4D preoperative motion model of the heart to the video view of the patient through the intraoperative endoscope of the daVinci surgical robot, in order to overlay the real video sequence with it. As the heart motion is cyclical it can be modelled using multiple reconstructions of cardiac gated coronary CT. This image sequence is used to construct a 4D model of the heart surface. We propose the use of photoconsistency between the two views through the da Vinci endoscope to align to the preoperative heart surface model from CT. We propose averaging of the photoconsistency over the cardiac cycle to improve the registration compared to a single view. Though there is considerable motion of the heart, after correct temporal alignment we suggest that the remaining motion should be close to rigid. Results are presented for simulated renderings and for real video of a beating heart phantom. We found much smoother sections at the minimum when using multiple phases for the registration, furthermore convergence was found to be better when more phases are used.