Efficient automatic 2D/3D registration of cardiac ultrasound and CT images

Hybrid ablations are a promising but difficult intervention for the treatment of atrial fibrillation. With the ultimate goal of providing navigation support for such procedures, we investigate a registration algorithm for routinely available preoperative and intraoperative images. We propose a fully automatic segmentation algorithm for the boundaries of cardiac chambers in intraoperative TEE ultrasound using a generic heart model. The resulting ultrasound segmentations are initially registered to the preoperative CT model using a frame-to-slice search, which is then refined using an efficient continuous optimisation. Results are presented for data sets from three patients who underwent hybrid ablations at our institution. The mean time to process a single ultrasound image from segmentation to registration with CT was 1.5 s, with the mean RMS error across the sequence being 4.8 mm. With further validation, these results show promise for surgical navigation in hybrid ablation procedures.