An improved algorithm for intraoperative registration of computed tomographic left atrial images

Abstract

Aims: Although anatomically accurate and highly detailed, preoperative computed tomographic (CT) images of the left atrium (LA) are of limited utility for guiding catheter navigation, in part because of changes in LA shape which occur between preoperative and intraoperative settings. Such changes may produce errors in spatial juxtaposition, or 'registration, of the CT image to the intraoperative environment. The goal of this study was to assess a new algorithm for CT image registration. Methods and results: In each of 10 patients, CT images were registered using LA endocardial points derived from intraoperative intracardiac echocardiography (CartoSound, Biosense). Two registration algorithms were compared: (i) CartoMerge (Biosense), a 'rigid' algorithm in which the CT image was not malleable; (ii) ImageMorph, a non-rigid algorithm in which CT image was malleable and was altered so as to more precisely fit the intraoperative point locations. There were no significant differences in LA volume or pulmonary vein antral dimensions on CT images after registration using CartoMerge vs. ImageMorph. Shape changes induced by ImageMorph were not concentrated in any one LA region. Registration quality was significantly better using ImageMorph, as was mock circumferential ablation accuracy. Conclusion: The potential for improved CT image-guided ablation accuracy using ImageMorph calls for further study to discern whether this algorithm yields tangible procedural and clinical benefits relative to currently available algorithms. © The Author 2010.