Joint Reconstruction and Registration Using Level Sets: Application to the Computer-guided Ablation of Atrial Fibrillation Jonghye Woo 1 , Byung-Woo Hong 2 , Sunil Kumar 3 , Indranill Basu Ray 4 and C.-C. Jay Kuo 1 1 Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089-2564 2 Computer Science Department, University of Los Angeles, Los Angeles, CA 90095 3 Electrical and Computer Engineering Department, San Diego State University, San Diego, CA 92182 4 School of Medicine and Dental Sciences, State University of New York at Buffalo, Buffalo, NY 14214 jonghyew@usc.edu, hong@cs.ucla.edu, skumar@mail.sdsu.edu indranillbasuray@yahoo.com, cckuo@sipi.usc.edu Abstract Use of 3D reconstructed cardiac images generated from Magnetic Resonance Imaging (MRI) and Computed Tomog- raphy (CT) play an important role in percutaneous image guided interventions. Image integration technique using these 3D images is especially useful for guiding a number of interventional therapies used to treat cardiac arrhythmias. This paper presents an implicit surface reconstruction and registration method based on a variational and partial dif- ference equation (PDE) method for the use of catheter ab- lation. Our optimal shape representation is based on the Electroanatomic mapping (EAM) data and a shape prior, and level set framework is incorporated for taking cardiac deformation and noise into account. We propose a novel im- age integration method which enables reconstruction and registration under non-rigid deformation simultaneously. Promising experimental results show the potential of our approach. 1. Introduction Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia encountered in clinical practice. In the United States alone, there are over 3.5 million patients with this disorder [16]. Atrial fibrillation can result in seri- ous complications, including congestive heart failure and thromboembolism. Despite the advances, drug therapy for controlling this disease is still unsatisfactory. This has led to the use of novel non-pharmacological, interventional ap- proaches based on creating percutaneous catheter based le- sion inside the heart. Lesions are delivered in the left atrial- pulmonary vein junction with an aim to electrically isolate these veins from the rest of the atrium. This, in effect, pro- tects the atrium from the fast heartbeats originating in the veins that both initiate and perpetuate atrial fibrillation. The present day procedure for interventional treatment of atrial fibrillation entails mapping the left atrium and the attached pulmonary veins using an Electroanatomic map- ping (EAM) system and this mapping information is used to deliver lesions as well. One important limitation of this system is its inability to create the anatomy. Instead a vir- tual shell is created to represent the atrial wall and the vein. The points on the atrial wall where the catheter is manually touched is used to create this shell [14]. This process can be made more precise if a real anatomy is used instead of the virtual shell. Thus to make use of the real anatomy, the images from MRI/CT and the data from EAM systems are integrated into the canonical reference frame. Image integration process for the heart aims to pro- vide an anatomical, physiological and functional represen- tation combining anatomical surface model that is formed by MRI/CT images and localized electrical information that is measured by EAM systems. This representation is of great use for an organ like the heart; which is an electrome- chanical organ, where electrical stimulus drives mechanical contractions. Clinical procedures such as catheter ablation can be made more precise with the help of image integra- tion as both the anatomical and electrical information is then available to the operator which ensures both safe catheter maneuverability and enables delivery of effective lesions with minimal collateral damage and complications. This is particularly important while doing ablations in a complex structure like the left atrium that is surrounded by important organs that are vulnerable to damage if lesions are not ap- propriately directed with close anatomical guidance. Fur- thermore, even the pulmonary veins themselves are liable