Dual time point 18F-FDG PET imaging for differentiating malignant from benign lung nodules

Objective: To evaluate the value of dual time point 18F-FDG PET imaging in differentiation of malignant from benign lung nodules. Methods: Thirty-two patients with malignant lung lesions and 15 patients with benign lesions underwent dual time point 18F-FDG PET imaging. The final diagnoses of these patients were proved either by histopathology or by biopsy, or by a clinical and radiographic follow-up. The imaging protocol included torso PET scanning (2-3 bed) at 40-65 min post-injection of 370-555 MBq FDG and then a whole body PET scanning at 1.5-2.5 h. The standardized uptake value (SUV) was calculated for both time points. All results were expressed as the percentage change in SUV. Results: The SUV of delayed images from malignant lesions increased over time compared with those of early images (54.59 ± 28.96)%. By contrast, the SUV of benign lung nodules remained stable or increased slightly over time (18.11±25.39)%. Conclusions: Dual time point imaging is a simple and practical method for detection of malignant lung lesions. The preliminary data suggests that malignant nodules have a greater rise of SUV in the delay images as compared to benign nodules, but pulmonary tuberculosis and granulomatous disease also have increased SUV