Central left lung tumour in a 67-year-old ex-smoker

67-year-old man, ex-smoker (45 pack-years), with a 4.5 cm central left upper lobe squamous cell carcinoma extending to the lower lobe hilum; FDG PET/CT and EBUS staging cT3 N0 M0. The surgeon anticipates a left pneumonectomy. FEV₁ 1.95 L (70% predicted), DLCO 64% predicted. Cardiac assessment unremarkable. Referred for quantitative lung perfusion scintigraphy to estimate postoperative lung function.