Feasibility study of quantitative radioactivity monitoring of tumor tissues inoculated into mice with a planar positron imaging system (PPIS)

Objective The objective of this study was to evaluate whether the radioactivity of tumor tissues inoculated into mice can be monitored quantitatively with a planar positron imaging system (PPIS). Methods 18 F-fluoro- d -glucose, 18 F-fluorothymidine, or d - 18 F-fluoromethyl tyrosine were intravenously administered into HeLa-bearing mice. In vivo uptake of each labeled compound in tumors was monitored with the PPIS, followed by the measurement of radioactivity in tumor tissue using tissue dissection analysis. The standardized uptake values (SUVs) in PPIS measurement and ex vivo tissue dissection analysis were derived using the tumor volume and tumor weight, respectively. Results Radioactivities of tumors in mice obtained via PPIS imaging correlated significantly with those by tissue dissection analysis. The SUV derived by the PPIS data and the estimated tumor volume correlated roughly with those by ex vivo tissue dissection analysis. Conclusions The results of our experiment indicate the feasibility of noninvasive, quantitative tumor monitoring in mouse/rat studies with the PPIS.