18F-FLT and 18F-FDG in Lung Cancer Imaging: Basic and Clinical Study

The study explores the diagnostic value of 18F-FLT and 18F-FDG in lung cancer nodules from cytological, animal xenograft, and clinical perspectives. A549 cells uptake two tracers respectively in vitro, and cells-tracers binding ratios were computed. Correlation analysis was carried out between cells-tracers binding ratios and Ki-67 expression in A549 cells. 18F-FDG and 18F-FLT micro PET/CT imaging of small animal models of inoculated A549 cells was conducted. The tumor-to-non-tumor (Background) uptake ratio (T/NT) was computed. Imaging data of 55 patients with SPNs examined by 18F-FLT and 18F-FDG PET/CT were collected. The study also explored the correlation between the Standardized Uptake Value (SUV) and Ki-67 expression of SPNs. Results showed that 18F-FDG uptake ratio of A549 cells is greater than 18F-FLT, and there was no correlation between 18F-FDG uptake ratio and proliferation index Ki-67 of A549 cells. However, the proliferation index Ki-67 had a significant positive correlation with 18F-FLT uptake ratio. The T/NT difference between 18F-FDG and 18F-FLT PET imaging in animal xenograft tumors was highly significant. Diagnostic sensitivity of 18F-FDG for lung cancer nodules was 92.9%, with 67% specificity and 73% accuracy. Diagnostic sensitivity of 18F-FLT for lung cancer was 71%, with 79% specificity and 76% accuracy. There was a positive correlation between lung cancer proliferation index Ki-67 expression and mean SUVmax of 18F-FDG and 18F-FLT PET imaging.