Direct comparison of computed tomography and magnetic resonance imaging for characterization of posterior left atrial morphology

Accumulating evidence points to the central importance of the posterior left atrium (PLA) for atrial fibrillation (AF). Catheter ablation intended to cure AF is increasingly practiced; performance and assessment of this procedure is enhanced by accurate imaging of PLA anatomy. Prior reports have suggested that both computed tomographic (CT) and magnetic resonance (MR) imaging techniques provide accurate PLA images. These techniques have never been compared directly. Twenty patients referred for catheter ablation underwent preoperative imaging using both CT and MR. Each technique was used to create a multidimensional image of the PLA. Within patients, morphologic and dimensional PLA indices, including number of individual pulmonary venoatrial junctions, presence of ostial branches, circumference of each venoatrial junction, venoatrial junction "non-circularity", and distance between ipsilateral superior and inferior venoatrial junctions, were well correlated. CT and MR-based images of the PLA appear comparable. Technique selection should involve considerations of toxicity, tolerance, and local resources.