A method for the determination of proximal pulmonary vein size using contrast-enhanced magnetic resonance angiography

Objectives: We sought to develop a reproducible method for characterizing the anatomy of the proximal pulmonary veins. Background: Contrast-enhanced three-dimensional magnetic resonance angiography (CE-MRA) is a commonly requested test before and after radiofrequency ablation for the treatment of atrial fibrillation. While CE-MRA readily visualizes the pulmonary veins, there is no standardized method for determining their size and cross-sectional anatomy. Methods: Data for 24 consecutive patients referred for pulmonary vein CE-MRA before an elective ablation procedure for the treatment of atrial fibrillation were analyzed. Detailed measurements of the pulmonary vein diameter, circumference, and cross-sectional area were obtained at three locations: the juncture of the pulmonary vein with the left atrium (LA) (position 1(J)), the narrowest segment within 5 mm of the juncture (position 2(5mm)), and at the location in the sagittal plane at which the pulmonary veins separate from the LA and from each other (position 3(Sag)). Intraobserver and interobserver variabilities were also determined for each method. Results: The left lower pulmonary vein was significantly smaller than the other pulmonary veins at positions 1(J) and 2(5mm) (p<0.05). The right upper pulmonary vein was significantly larger than the other pulmonary vein at position 3(Sag) (p<0.05). At positions 1(J) and 25mm, the diameter had a low correlation with the circumference and cross-sectional area. At position 3(Sag), the major and minor axis dimensions had a very high correlation with the circumference and cross-sectional area. The intraobserver and interobserver variabilities were substantially lower (better) for position 3(Sag). Conclusions: Pulmonary vein diameter measurements are highly variable and do not reflect true anatomic variation in cross-sectional anatomy. A sagittal method of determining pulmonary vein size was highly reproducible and may therefore be advantageous for use in patients likely to need serial examinations.