The vascular converging points of the right pulmonary hilus and their diagnostic significance.

The shadows of the right descending pulmonary artery, the superior pulmonary vein crossing it, the middle lobe artery, and branches of the artery supplying the superior segment of the lower lobe converge distinctly at the right hilus. Because the right pulmonary artery bifurcates within the mediastinum, the arteries of the right upper lobe form a second though less obvious converging point above this level. In contrast, the left pulmonary artery does not bifurcate until it reaches the left hilus, providing only a single converging point on that side. A survey of 100 chest radiographs showed that the two converging points on the right could be distinguished in 95 cases, with the upper one being situated somewhat above the single point on the left in 83. In the absence of lobar resection, finding only one converging point on the right is suggestive of collapse of either the upper or lower lobe, whereas visualization of both points excludes major atelectasis.