Magnetic resonance angiography virtual endoscopy in the assessment of pulmonary veins before radiofrequency ablation procedures for atrial fibrillation.

Magnetic resonance angiography (MRA) is a safe and non-invasive imaging method that can readily depict the pulmonary veins (PV), whose imaging has acquired momentum with the advent of new techniques for radiofrequency ablation of atrial fibrillation (AF). We evaluated whether virtual endoscopy from 3D MRA images (MRA-VE) is feasible in studying the morphology of PV. Fifty patients with AF underwent pre-ablative MRA (1.5 T). Images were acquired with axial T-2 weighted and 3D-SPGR sequences after intravenous administration of Gd-DTPA and automatic triggering. Postprocessing was performed by an experienced radiologist with maximum intensity projection (MIP) and virtual endoscopy software (Navigator, GEMS). The venoatrial junction was visualized with MRA-VE in 49 of 50 patients (98.0%). Twenty-seven patients (55.1%) had two ostia on both sides, 13 patients (26.5%) had two ostia on the right and a single common ostium on the left, 5 patients (10.2%) had accessory PV and 4 patients (8.2%) had both an accessory right PV and a single common ostium on the left. Flythrough navigation showed the number and spatial disposition of second-order PV branches in 48 out of 49 patients (98.0%). MRA-VE is an excellent tool for at-a-glance visualization of ostia morphology, navigation of second-generation PV branches and easy endoluminal assessment of left atrial structures in pre-ablative imaging.