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Updated: Jun 28, 2026
Radionuclide-fluorescence Reporter Gene Imaging to Track Tumor Progression in Rodent Tumor Models
Published on: March 13, 2018
Kinetic modeling of 3'-deoxy-3'-18F-fluorothymidine for quantitative cell proliferation imaging in subcutaneous tumor
Su Jin Kim1, Jae Sung Lee, Ki Chum Im
1Department of Nuclear Medicine, College of Medicine, Seoul National University, Seoul, Korea.
Unlabelled:
3'-Deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) is a thymidine analog that was developed for measuring tumor proliferation with PET. The aim of this study was to establish a kinetic modeling analysis method for quantitative (18)F-FLT PET studies in subcutaneous tumor models in mice.
Methods:
To explore the validity of an image-derived left ventricular input function, we measured equilibrium constants for plasma and whole blood and metabolite fractions in blood after (18)F-FLT injection. In parallel, dynamic (18)F-FLT PET scans were acquired in 24 mice with a small-animal dedicated PET scanner to compare arterial blood activities obtained by PET and blood sampling. We then investigated kinetic models for (18)F-FLT in human epithelial carcinoma (A431) and Lewis lung carcinoma tumor models in mice. Three-compartment models with reversible phosphorylation (k(4) not equal 0, 3C5P) and irreversible phosphorylation (k(4) = 0, 3C4P) and a 2-compartment model (2C3P) were examined. The Akaike information criterion and F statistics were used to select the best model for the dataset. Gjedde-Patlak graphic analysis was performed, and standardized uptake values in the last frame were calculated for comparison purposes. In addition, quantitative PET parameters were compared with Ki-67 immunostaining results.
Results:
(18)F-FLT equilibrated rapidly (within 30 s) between plasma and whole blood, and metabolite fractions were negligible during PET scans. A high correlation between arterial blood sampling and PET data was observed. For 120-min dynamic PET data, the 3C5P model best described tissue time-activity curves for tumor regions. The net influx of (18)F-FLT (K(FLT)) and k(3) obtained with this model showed reasonable intersubject variability and discrimination ability for tumor models with different proliferation properties. The K(FLT) obtained from the 60- or 90-min data correlated well with that obtained from the 120-min data as well as with the Ki-67 results.
Conclusion:
The image-derived arterial input function was found to be feasible for kinetic modeling studies of (18)F-FLT PET in mice, and kinetic modeling analysis with an adequate compartment model provided reliable kinetic parameters for measuring tumor proliferation.
