Comparison of [ 18 F]FIMP, [ 11 C]MET, and [ 18 F]FDG PET for early-phase assessment of radiotherapy response

• Published in: Scientific reports Vol. 13; no. 1; p. 1961
• Main Authors: Nozaki, Satoshi, Nakatani, Yuka, Mawatari, Aya, Shibata, Nina, Hume, William E, Hayashinaka, Emi, Wada, Yasuhiro, Doi, Hisashi, Watanabe, Yasuyoshi
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 03.02.2023; Nature Publishing Group UK; Nature Portfolio
• Subjects: Carbon Radioisotopes; Cell Line, Tumor; Fluorodeoxyglucose F18; Inflammation; Irradiation; Positron-Emission Tomography; Radiation therapy; Radiopharmaceuticals; Tumors
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-29166-y

Several limitations of [ F]FDG have been reported, such as nonspecific uptake of inflammation foci. Moreover, [ C]MET has been found to accumulate in normal and inflammatory tissues as well as tumors. To increase specificity to tumor tissues, PET probes with tumor-specific molecular targets have been actively developed. [ F]FIMP was found to be highly accumulated in LAT1-positive tumors but not in inflamed tissue. The aim of this study was to explore whether [ F]FIMP can be used for the early-phase evaluation of radiotherapy accompanied by inflammation, and compare its effectiveness with those of [ C]MET and [ F]FDG. Tumor uptake of [ F]FIMP decreased at day 1 after irradiation, and remained low until day 14. Comparatively, that of [ F]FDG initially decreased at day 3 but was transiently elevated at day 7 and then decreased again at day 10. Decreased tumor uptake of [ C]MET was observed at day 10. In line with the uptake of [ F]FIMP, the ratio of Ki-67 immuno-positive cells in tumor tissues significantly decreased at day 1, 7, and 10 as compared with that in the control. These findings suggest that [ F]FIMP may be a PET probe involved in the early detection and prediction of radiotherapy efficacy, although further clarification is needed.