The B1 defective type of bifurcated right upper lobe bronchus.

Background: As the more application of high-resolution computed tomography (HRCT), a great number of ground glass opacity (GGO) is identified. Video-assisted thoracoscopic surgery (VATS) segmentectomy is technically more difficult than lobectomy because of the anatomical complexity. Three-dimensional computed tomography bronchography angiography (3D-CTBA) is a powerful tool for thoracic surgeons to analyze pulmonary anatomy, allowing a better understanding of the pulmonary anatomy in each patient. Here we encountered seven cases of bifurcated right upper bronchus (B1 defective). The variation in vascular pattern of these patients is analyzed.

Methods: Between October 2018 and December 2018, a consecutive 162 patients with pulmonary lesions were admitted and underwent 3D-CTB prior to surgery. A total of seven cases of bifurcated right upper bronchus (B1 Defective) were identified. Then 3D-CTBA reconstruction was performed by Syngo MultiModality Workplace (Software: Syngo MMWP, Version: VF40A). Radiology colleagues processed all 3D images and thoracic surgeons confirmed the validity of all reconstructions.

Results: The mean age of the seven patients (3 females and 4 males) is 54 years. According to the branches of artery, they are divided into two types: "Tr. sup + A. asc" (2/7, 28.6%) and "Tr. sup + Tr. inf + A. asc" (5/7, 71.4%). According to the branches of A2 asc, another two types can be divided: type A, two branches of A2a asc + A2b asc (4/7, 57.1%) and type B, only one branch of A2b asc (3/7, 42.9%). Types can also be divided according to the branches of A2 rec: A, no A2 rec (4/7, 57.1%); B, one branch of A2a rec (2/7, 28.6%); C, two branches of A2a rec + A2b rec (1/7, 14.3%). According to the origins of A3, three types can be divided: A, A3 origins from Tr. inf (1/7, 14.3%); B, A3 origins from Tr. sup (2/7, 28.6%); C, A3 origins from both Tr. sup and Tr. inf (4/7, 57.1%).

Conclusions: The "defective B1" type of bifurcated right upper lobe (RUL) bronchus is relatively rare. A pre-operative understanding of its anatomical features, especially the vascular variation patterns, may be helpful for completing a satisfactory segmentectomy. 3D-CTBA is a powerful tool, allowing a better understanding of the pulmonary anatomy in each patient before and during surgical procedures.