Role of multiple dual-phase (18)F-FDG PET/CT metabolic parameters in differentiating adenocarcinomas from squamous cell carcinomas of the lung

PURPOSE: To evaluate the ability of multiple dual-phase (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) metabolic parameters to distinguish the histological subtypes of non-small cell lung cancer (NSCLC). METHODS: Data from 127 patients with non-small cell lung cancer who underwent preoperative dual-phase (18)F-FDG PET/CT scanning at the PET-CT center of our hospital from December 2020 to October 2021 were collected, and the metabolic parameters of their primary lesions were measured and analyzed retrospectively. Intraclass correlation coefficients (ICC) were calculated for consistency between readers. Metabolic parameters in the early (SUV(peak), SUV(mean), SUV(min), SUV(max), MTV, and TLG) and delayed phases (dpSUV(peak), dpSUV(mean), dpSUV(min), dpSUV(max), dpMTV, and dpTLG) were calculated. We drew receiver operating characteristic (ROC) curves to compare the differences in different metabolic parameters between the adenocarcinoma (AC) and squamous cell carcinoma (SCC) groups and evaluated the ability of different metabolic parameters to distinguish AC from SCC. RESULTS: Inter-reader agreement, as assessed by the intraclass correlation coefficient (ICC), was good (ICC = 0.71, 95% CI:0.60–0.79). The mean MTV, SUV(max), TLG, SUV(peak), SUV(mean), dpSUV(max), dpTLG, dpSUV(peak), dpSUV(mean), and dpSUV(min) of the tumors were significantly higher in SCC lesions than in AC lesions (P = 0.049, < 0.001, 0.016, < 0.001, 0.001, < 0.001, 0.018, < 0.001, 0.001, and 0.001, respectively). The diagnostic efficacy of the metabolic parameters in (18)F-FDG PET/CT for differentiating adenocarcinoma from squamous cell carcinoma ranged from high to low as follows: SUV(peak) (AUC = 0.727), SUV(max) (AUC = 0.708), dpSUV(max) (AUC = 0.699), dpSUV(peak) (AUC = 0.698), TLG (AUC = 0.695), and dpTLG (AUC = 0.692), SUV(mean) (AUC = 0.690), dpSUV(mean) (AUC = 0.687), dpSUV(min) (AUC = 0.680), SUV(min) (AUC = 0.676), and MTV (AUC = 0.657). CONCLUSIONS: Squamous cell carcinoma of the lung had higher mean MTV, SUV(max), TLG, SUV(peak), SUV(mean), SUV(min), dpSUV(peak), dpSUV(mean), dpSUV(min), dpSUV(max), and dpTLG than AC, which can be helpful tools in differentiating between the two. The metabolic parameters of the delayed phase (2 h after injection) (18)F-FDG PET/CT did not improve the diagnostic efficacy in distinguishing lung AC from SCC. Conventional dual-phase (18)F-FDG PET/CT is not recommended.