Comparison of Optimizers for 2D/3D Registration for Fusion of Ultrasound and X-Ray

Ultrasound and X-ray are two facilitating imaging modalities in the field of transcatheter-based minimally invasive procedures in structural heart disease. X-ray fluoroscopy provides excellent instrument imaging and ultrasound shows high-quality images of soft tissue. A fusion of both modalities can potentially improve the surgical workflow and the catheter navigation. A current approach shows the fusion of X-ray fluoroscopy with trans-esophageal echo (TEE) with the help of 2D/3D registration. An ultrasound probe model is registered to X-ray images which inherently provides a registration of ultrasound images to X-ray. In this paper, we evaluate the accuracy and the performance of four optimizing algorithms (Powell, Nelder-Mead, BFGS, CMA-ES) while registering digitally reconstructed radiographs (DRR) of the model to X-ray images. The DRRs were generated by mesh-rendering, not by ray casting. The optimizers show significant differences in accuracy and runtime.