Differential diagnosis protocols of ¹⁸F-FDG and ¹⁸F-FLT PET/CT for solitary pulmonary nodules

Objective To investigate the diagnostic values of ¹⁸F-FDG and 3′-deoxy-3′-¹⁸F-fluorothymidine(¹⁸F-FLT) PET/CT for solitary pulmonary nodules. Methods ¹⁸F-FDG and ¹⁸F-FLT PET/CT imaging were performed in 40 patients with solitary pulmonary nodules. All cases were confirmed by pathology or follow-up. The diagnostic values of ¹⁸F-FDG SUV_max, ¹⁸F-FLT SUV_max, and ¹⁸F-FLT/the same level of vertebral SUV_max for pulmonary malignant tumor were compared using the receiver operating characteristic(ROC) curves. ¹⁸F-FDG and ¹⁸F-FLT imaging results were analyzed by visual observation and semi-quantitative analysis. The diagnostic efficiencies of the different diagnostic methods were compared. Results Areas under the ROC curves of ¹⁸F-FDG SUV_max, ¹⁸F-FLT SUV_max, and ¹⁸F-FLT/ same level of vertebral SUV_max were 0.687, 0.821, and 0.817, respectively. The diagnostic sensitivities, specificities, and accuracies of tested diagnostic tools were as follows:¹⁸F-FDG SUV_max > 2.5 as the malignant diagnostic criteria, 88.2%, 73.9% and 80.0%; ¹⁸F-FLT SUV_max > 2.0 as the malignant diagnostic criteria, 58.8%, 82.6% and 72.5%; ¹⁸F-FDG PET/CT visual analysis of scoring method, 94.1%, 91.3% and 92.5%; and ¹⁸F-FLT PET/CT for visual analysis of scoring method 88.2%, 65.2% and 75.0%. Conclusions ¹⁸F-FLT SUV_max and ¹⁸F-FLT/vertebral SUV_max showed higher accuracies in diagnosing solitary pulmonary modules compared with ¹⁸F-FDG SUV_max. ¹⁸F-FDG PET/CT visual scoring method was the most effective in diagnosing solitary pulmonary nodules.