Dual-time-point 18 F-FDG PET/CT in the diagnosis of solitary pulmonary lesions in a region with endemic granulomatous diseases

Objective Granulomatous diseases (GDs) can be metabolically active and indistinguishable from lung cancer on 18 F-fluorodeoxyglucose positron emission tomography ( 18 F-FDG PET) imaging. Evaluation of solitary pulmonary lesions remains a diagnostic challenge in regions with endemic GD. This study sought to determine the efficacy of dual-time-point (DTP) 18 F-FDG PET/computed tomography (CT) imaging in diagnosing solitary pulmonary lesions from such regions. Methods A total of 50 patients with solitary pulmonary nodules or masses with confirmed histopathological diagnoses underwent DTP 18 F-FDG PET/CT imaging at 1 and 3 h after tracer injection. The maximum standardized uptake value (SUV max ) on early and delayed scans (SUV 1h and SUV 3h , respectively) and retention index (RI) were calculated for each pulmonary lesion. Receiver operating characteristic analysis was performed to evaluate the discriminating validity of the parameters. Results There were 37 malignant and 13 benign solitary pulmonary lesions. Eight of the 13 (62 %) benign lesions were GDs. The sensitivity/specificity/accuracy of SUV 1h , SUV 3h and RI were 84/69/80 %, 84/85/84 %, and 81/54/74 %, respectively. SUV 3h had the best diagnostic performance, especially regarding specificity. The values of SUV 1h and SUV 3h were significantly different between malignant lesions and GD, while the RI values of malignant lesions and GD were both high (18.6 ± 19.5 and 18.7 ± 15.3 %, respectively; P = not significant). Conclusion SUV 3h appeared to improve the diagnostic specificity of 18 F-FDG PET/CT in evaluating solitary pulmonary lesions from regions with endemic GD.