New findings on the three-dimensional anatomical relations between the bronchi and pulmonary blood vessels at the pulmonary hilum.

During the 1940s, considerable knowledge was acquired about the anatomy of pulmonary segments, and anatomical terms were proposed and have been widely accepted. In recent years, minimally invasive and thoracoscopic segmentectomy has been performed with a versatile sublobar resection approach on patients with early peripheral lung cancer, metastatic lung tumors, and undiagnosed nodules. The three-dimensional (3D) anatomy of the bronchi and the pulmonary vessels has also been studied in individual patients. Three-dimensional models of the bronchi and pulmonary vessels were prepared using homemade software from computed tomograms (CT) of the chests of patients scheduled to undergo surgical procedures. Using these models, the authors examined the 3D positional relationships of the segmental broncho-arterial triangle (SBAT) created by three points defined by the origins and courses of the bronchi and the pulmonary arteries, which are located apart from each other at the pulmonary hilum, and the segmental pulmonary veins (SPV), which run near the SBAT. In the left and right upper lobes, many branches of the pulmonary arteries and parallel bronchi in subsegments were widely separated at the origin of the pulmonary hilum, creating a relatively large SBAT. However, as an exceptional case, an SPV passed through an SBAT in only one of 158 patients. To our knowledge, no similar findings have been documented previously. Our findings could help to determine resection surfaces for thoracoscopic segmentectomy in the future, and provide new insights into the 3D anatomy and development of the lung.