Concealed right upper lobe pulmonary venous variants on 3D-CTBA: morphological characterization and surgical implications.

Introduction: The surgical anatomy of the right upper lobe pulmonary vein is variable and rare anomalies often go unnoticed in the first intraoperative exposure. Methods: 3D-CTBA reconstructions were performed on 307 right-sided contrast-enhanced chest CT data with full segmentation of the arterial, venous and bronchial systems. Results: Anomalous right upper lobe vein anatomy was detected in 23 cases (7.49%) consisting of 18 right top pulmonary veins (RTPVs) and 5 cases of proposed cranially displaced central vein (CDCV). In all 18 RTPVs, a single venous trunk collecting S2 drainage followed a retrobronchial course posterior to the right main bronchus or bronchus intermedius. Thirteen drained directly into left atrium. The other five had translobar confluence with the inferior pulmonary vein system; one drained first into V6 before joining the inferior pulmonary vein. Surgically relevant arterial anomalies were concentrated in the RTPV subgroup. A central vein configuration was also identified, in which the venous trunk coursed in the interval between B1 and the adjacent roots of B2 and B3, consistently more cranial than expected. This pattern is called the cranially displaced central vein (CDCV). Discussion: Recognizing these precise anatomical configurations via preoperative 3D-CTBA is essential to avoid unexpected intraoperative hemorrhage during thoracic procedures.