Registration between transesophageal echocardiography TEE and x-ray fluoroscopy XRF has recently been introduced as a potentially useful tool for advanced image guidance of structural heart interventions. Algorithms for registration at fluoroscopic imaging frame rates 15-30 fps have yet to be reported, despite the fact that probe movement resulting from cardiorespiratory motion and physician manipulation can introduce non-trivial registration errors during untracked image frames. In this work, we present a novel algorithm for GPU-accelerated 2D/3D registration and apply it to the problem of TEE probe tracking in XRF sequences. Implementation in CUDA C resulted in an extremely fast similarity computation of < 80 μs, which in turn enabled registration frame rates ranging from 23.6-92.3 fps. The method was validated on simulated and clinical datasets and achieved target registration errors comparable to previously reported methods but at much faster registration speeds. Our results show, for the first time, the ability to accurately register TEE and XRF coordinate systems at fluoroscopic frame rates without the need for external hardware. The algorithm is generic and can potentially be applied to other 2D/3D registration problems where real-time performance is required.
['Charles R. Hatt', 'Michael A. Speidel', 'A. Raval']
Robust 5DOF Transesophageal Echo Probe Tracking at Fluoroscopic Frame Rates