CT findings of anomalous systemic artery to the left lower lobe: Comparison with pulmonary sequestration in the left lower lobe

•Hemoptysis is more common in ASALLL than in PS.•An anomalous artery had a larger calibre in ASALLL.•GGO, normal bronchial distribution, dilated pulmonary veins favour ASALLL over PS.

AimTo analyse and compare CT findings of anomalous systemic artery to the left lower lobe (ASALLL) and pulmonary sequestration (PS) in the left lower lobe (LLL).Materials and methodsThe present study cohort comprised 16 patients with ASALLL and 25 patients with PS in the LLL confirmed by surgical and pathological findings. Medical records and CT images were reviewed retrospectively.ResultsCough and sputum were more common in PS (84% and 60%, respectively) than in ASALLL (25% and 12.5%, respectively; p < 0.05). Haemoptysis was more common in ASALLL (100%) than in PS (24%; p < 0.05). The frequency of ground-glass opacity (GGO), normal bronchial distribution, dilated left inferior pulmonary veins, and absence of the interlobar artery distal to the origin of the superior segmental artery in the LLL differed significantly between ASALLL and PS. A mass was less common in ASALLL (0%) than in PS (88%; p < 0.01). The mean diameters of the anomalous artery (12.10 ± 1.49 mm) and left inferior pulmonary veins (13.20 ± 2.19 mm) in ASALLL were significantly larger than those (6.73 ± 2.59 mm, 10.04 ± 1.55 mm) in PS. The threshold diameters of the anomalous artery and left inferior pulmonary vein for ASALLL were 9.75 and 11.75 mm, respectively. The presence of an anomalous artery arising from the thoracic aorta was not different between ASALLL (100%) and PS (72%).ConclusionThe following imaging features favour ASALLL over PS in the LLL: a larger anomalous systemic artery arising from the thoracic aorta, dilated left inferior pulmonary veins, absence of the interlobar artery distal to the origin of the superior segmental artery, normal bronchial distribution, and GGO in the LLL.