Precision of quantitative parameters of ¹⁸F-FDG PET/CT in a rabbit VX2 tumor model

Background: The precision reflecting repeated measurement error of quantitative parameters of flourine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18-FDG PET/CT) for evaluating the therapeutic effect of solid tumor can help observe whether a real biologic change in glucose metabolism occurred, or if the change was caused by errors before and after the treatment. Methods: A total of 18 VX2 tumor-bearing male New Zealand rabbits confirmed by pathology were used, three of which were used for determining the best scanning time point after injection and 15 for a precision experiment by repeating PET/CT scans for three consecutive days. The PET volume computer-assisted reading (PET VCAR) software (GE Healthcare) was used to analyze the standardized uptake value (SUV) and total lesion glycolysis (TLG) parameters. The lean body mass (LBM) to calculate the SUV corrected for lean body mass (SUL) parameters was measured using dual energy X-ray absorptiometry (DXA). The precision was represented as the coefficient of variation of root mean square (RMS-CV) and standard deviation of root mean square (RMS-SD). The least significant change (LSC) was also calculated when considering precision. Results: The precision of SUV parameters, including SUVmax, SUVmean and SUVpeak ranged from 18.3% to 18.8%, which was similar to that of the SUL parameters (18.0-18.4%). Using 80% confidence interval (CI), the LSC of SUVmax and SULpeak were 33.1% and 33.3%, respectively; using 95% CI, the LSC of SUVmax and SULpeak were 50.1% and 51.0%, respectively. Conclusions: This research established the method of precision in a rabbit VX2 tumor model, which can be used for monitoring changes to assess the effects of drug treatment on solid tumors in experimental studies with 18F-FDG PET/CT imaging.