Estimation of the net influx rate K i and the cerebral metabolic rate of glucose MR glc using a single static [ 18 F]FDG PET scan in rats.

Since accurate quantification of 2-deoxy-2- ¹⁸ F-fluoro-D-glucose ([ ¹⁸ F]FDG) positron emission tomography (PET) requires dynamic acquisition with arterial input function, more practical semi-quantitative (static) approaches are often preferred. However, static standardized uptake values (SUV) are typically biased due to large variations in body weight (BW) occurring over time in animal studies. This study aims to improve static [ ¹⁸ F]FDG PET SUV quantification by better accounting for BW variations in rats. We performed dynamic [ ¹⁸ F]FDG PET imaging with arterial blood sampling in rats (n = 27) with different BW (range 0.230-0.487 kg). By regressing the area under the curve of the input function divided by injected activity against BW (r ² =0.697), we determined a conversion factor f(BW) to be multiplied with SUV and SUV _glc to obtain ratSUV and ratSUV _glc , providing an improved estimate of the net influx rate K _i (r = 0.758, p<0.0001) and cerebral metabolic rate of glucose MR _glc (r = 0.906, p<0.0001), respectively. In conclusion, the proposed ratSUV and ratSUV _glc provide a proxy for the K _i and MR _glc based on a single static [ ¹⁸ F]FDG PET SUV measurement improving clinical significance and translation of rodent studies. Given a defined strain, sex, age, diet, and weight range, this method is applicable for future experiments by converting SUV with the derived f(BW).
Competing Interests: Declaration of Competing Interest The authors declare no competing interest.
(Copyright © 2021. Published by Elsevier Inc.)