Reproducibility of 3′-Deoxy-3′-18F-Fluorothymidine MicroPET Studies in Tumor Xenografts in Mice

Journal of Nuclear Medicine

Mangal Dandekar¹  Jinha M. Park¹  Stan Louie¹  Jeffrey R. Tseng¹  Sanjiv S. Gambhir¹  Murugesan Subbarayan¹  Zhen Cheng¹ 

关键词: ¹⁸F-FLT;    microPET;    reproducibility;    tumor xenograft;    drug development;   

DOI  :  

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

3′-Deoxy-3′-18F-fluorothymidine (18F-FLT) has been used to image tumor proliferation in preclinical and clinical studies. Serial microPET studies may be useful for monitoring therapy response or for drug screening; however, the reproducibility of serial scans has not been determined. The purpose of this study was to determine the reproducibility of 18F-FLT microPET studies. Methods: C6 rat glioma xenografts were implanted into nude mice (n = 9) and grown to mean diameters of 5–17 mm for approximately 2 wk. A 10-min acquisition was performed on a microPET scanner approximately 1 h after 18F-FLT (1.9–7.4 MBq [50–200 μCi]) was injected via the tail vein. A second microPET scan was performed approximately 6 h later on the same day after reinjection of 18F-FLT to assess for reproducibility. Most of the mice were studied twice within the same week (for a total of 17 studies). Images were analyzed by drawing an ellipsoidal region of interest (ROI) around the tumor xenograft activity. Percentage injected dose per gram (%ID/g) values were calculated from the mean activity in the ROIs. Coefficients of variation and differences in %ID/g values between studies from the same day were calculated to determine the reproducibility after subtraction of the estimated residual tumor activity from the first 18F-FLT injection. Results: The coefficient of variation (mean ± SD) for %ID/g values between 18F-FLT microPET scans performed 6 h apart on the same day was 14% ± 10%. The difference in %ID/g values between scans was −0.06% ± 1.3%. Serum thymidine levels were mildly correlated with %ID/g values (R2 = 0.40). Tumor size, mouse body weight, injected dose, and fasting state did not contribute to the variability of the scans; however, consistent scanning parameters were necessary to ensure accurate studies, in particular, controlling body temperature, the time of imaging after injection, and the ROI size. Conclusion: 18F-FLT microPET mouse tumor xenograft studies are reproducible with moderately low variability. Serial studies may be performed to assess for significant changes in therapy response or for preclinical drug development.

【 授权许可】

Unknown