In Vivo Characterization of Proliferation for Discriminating Cancer from Pancreatic

We have determined the ability of PET with the thymidine analog 39-deoxy-39-18F-fluorothymidine (FLT) to detect pancreatic can-cer and to differentiatemalignant frombenign pancreatic lesions. Methods: In this prospective study, 18F-FLT PET was performed on 31 patients with undefined pancreatic lesions. Routine diag-nostic procedures included endoscopic ultrasound, MRI, or mul-tislice helical CT of the upper gastrointestinal tract in all patients. Uptake of 18F-FLT was evaluated semiquantitatively by calcula-tion of mean and maximal standardized uptake values (SUVs). Results were correlated to the reference methods, which were histopathology (23/31) or cytology/clinical follow-up (8/31). Re-sults: All 10 benign pancreatic lesions were negative on 18F-FLT PET and showed only background activity (specificity, 100%; 90 % confidence interval, 74%2100%). On visual interpretation, 15 of 21 malignant tumors presented as focal 18F-FLT uptak