Geometry and Dimensions of the Pulmonary Artery Bifurcation in Children and Adolescents: Assessment in Vivo by Contrast-Enhanced MR-angiography

We sought to establish normal values for the diameters of the main (MPA), right (RPA), and left (LPA) pulmonary arteries and for the angles describing the geometry of the pulmonary artery bifurcation in children by using contrast-enhanced magnetic resonance angiography (CE-MRA). CE-MRA was performed in 69 children without cardiovascular disease. The median age was 10 ± 4.9 years (range 2–20), weight 37.4 ± 18.5 kg (10–82), body surface area (BSA) 1.18 ± 0.4 m2 (0.48–2.07). The pulmonary artery diameters and angles were measured at standardized sites and projections. Regression analysis of diameters and angles in relation to BSA demonstrated linear relationship between the cross-sectional diameters of the pulmonary arteries and the square root of BSA (BSA0.5). Normalized mean diameters were for the MPA 17.6 ± 5.1 mm/m2, origin of RPA 13.1 ± 2.9 mm/m2, origin of LPA 14.2 ± 2.9 mm/m2. The MPA showed a mean antero-posterior inclination of 33° ± 8° and a lateral leftward angulation of 18° ± 5°. The mean angle of the bifurcation was 99.5° ± 10.3°. Both side branches showed a supero-inferior course of the proximal segments, steeper for the RPA (7.7° ± 6.5°) than for the LPA (2.1° ± 7.8°). Normative curves in relation to BSA are presented for all measurements. This study provides normative values by CE-MRA for the main pulmonary artery and its side branches in children during somatic growth. These data can be used for identifying pulmonary arteries anomalies in children, and evaluate the need and the modality for treatment.