Dual-Phase 18F-FDG PET in the Diagnosis of Pulmonary Nodules with an Initial Standard Uptake Value Less Than 2.5

OBJECTIVE. A cutoff standard uptake value (SUV) of 2.5 has been commonly adopted for 18F-FDG PET to evaluate pulmonary lesions, but false results can occur. Studies have shown the usefulness of delayed PET for improving accuracy. This study was designed to examine the efficiency of delayed PET of pulmonary nodules with an initial mean SUV less than 2.5.MATERIALS AND METHODS. Dual-phase FDG PET studies were conducted with imaging 1 and 2 hours after FDG injection, and pulmonary lesions with an initial mean SUV less than 2.5 were identified. Nodules with pathologic reports were included in the study. The differences in mean SUV, maximal SUV, and retention index between benign and malignant pulmonary lesions were analyzed. Receiver operating characteristic analysis was performed to evaluate the discriminating validity of the retention index.RESULTS. A total of 31 lesions (15 benign, 16 malignant) were included in the study. Among the benign lesions, 12 were granulomatous inflammation, including 10 tuberculos...