Comparison of Positron Emission Tomography Using 2-[(18)F]-fluoro-2-deoxy-D-glucose and 3-deoxy-3-[(18)F]-fluorothymidine in Lung Cancer Imaging

BACKGROUND: The detection of solitary pulmonary nodules (SPNs) that may potentially develop into a malignant lesion is essential for early clinical interventions. However, grading classification based on computed tomography (CT) imaging results remains a significant challenge. The 2-[(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET)/CT imaging produces both false-positive and false-negative findings for the diagnosis of SPNs. In this study, we compared (18)F-FDG and 3-deoxy-3-[(18)F]-fluorothymidine ((18)F-FLT) in lung cancer PET/CT imaging. METHODS: The binding ratios of the two tracers to A549 lung cancer cells were calculated. The mouse lung cancer model was established (n = 12), and micro-PET/CT analysis using the two tracers was performed. Images using the two tracers were collected from 55 lung cancer patients with SPNs. The correlation among the cell-tracer binding ratios, standardized uptake values (SUVs), and Ki-67 proliferation marker expression were investigated. RESULTS: The cell-tracer binding ratio for the A549 cells using the (18)F-FDG was greater than the ratio using (18)F-FLT (P < 0.05). The Ki-67 expression showed a significant positive correlation with the (18)F-FLT binding ratio (r = 0.824, P < 0.01). The tumor-to-nontumor uptake ratio of (18)F-FDG imaging in xenografts was higher than that of (18)F-FLT imaging. The diagnostic sensitivity, specificity, and the accuracy of (18)F-FDG for lung cancer were 89%, 67%, and 73%, respectively. Moreover, the diagnostic sensitivity, specificity, and the accuracy of (18)F-FLT for lung cancer were 71%, 79%, and 76%, respectively. There was an obvious positive correlation between the lung cancer Ki-67 expression and the mean maximum SUV of (18)F-FDG and (18)F-FLT (r = 0.658, P < 0.05 and r = 0.724, P < 0.01, respectively). CONCLUSIONS: The (18)F-FDG uptake ratio is higher than that of (18)F-FLT in A549 cells at the cellular level. (18)F-FLT imaging might be superior for the quantitative diagnosis of lung tumor tissue and could distinguish lung cancer nodules from other SPNs.