Reproducibility of proliferation measurements of [18f]-fluoro-3'-deoxy-3'-l-fluorothymidine PET in patients with lung cancer

[18F] -fluoro-3' -deoxy-3' -L-fluorothymidine (FLT) has been developed as a proliferation tracer. The purpose of this study was to evaluate the reproducibility of serial FLT-PET to define objective criteria for the evaluation of treatment-induced changes. Twelve patients (8 women, and 4 men; age 59 9 yrs) with untreated advanced non small cell lung cancer underwent FLT-PET twice within 2 days. Using a PET-CT scanner, images of chest field were acquired at 1 hr after intravenous injection of FLT. We measured maximal standardized uptake value (SUVmax) for a malignant lung lesion with highest uptake, SUV75 of T-spine bone marrow using a threshold (75% of SUVmax) defined volume of interest (VOI), and SUVmean for liver and heart blood pool using a fixed VOI. The reproducibility of SUVs was evaluated by Bland-Altaman analysis including calculation of mean and standard deviation of the difference between two tests, mean percentage difference and reliability (intraclass correlation = ) on a patient by patient basis. The mean SUVmax of lung cancer lesion from two tests was not different significantly (Table, p > 0.05). The reproducibility of measurement of maxSUV of malignant lung lesion in FLT-PET was excellent with a small variability and a high reliability. In all patients, the difference between two PET scans was less 0.4 (95% limit of agreement), SD of mean relative difference was 8.43% and ICC was 0.99. SUVs in bone marrow, blood pool and liver also measured reproducibly. Proliferation measurements of FLT-PET using SUVs provide highly reproducible quantitative parameters in malignant lung lesions