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_ι), 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 _ι and 25_mm (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_ι and 25_mm, 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.