Performing repeated quantitative small-animal PET with an arterial input function is routinely feasible in rats

Abstract

Performing quantitative small-animal PET with an arterial input function has been considered technically challenging. Here, we introduce a catheterization procedure that keeps a rat physiologically stable for 1.5 mo. We demonstrated the feasibility of quantitative small-animal 18F-FDG PET in rats by performing it repeatedly to monitor the time course of variations in the cerebral metabolic rate of glucose (CMRglc). Methods: Aseptic surgery was performed on 2 rats. Each rat underwent catheterization of the right femoral artery and left femoral vein. The catheters were sealed with microinjection ports and then implanted subcutaneously. Over the next 3 wk, each rat underwent 18F-FDG quantitative small-animal PET 6 times. The CMRglc of each brain region was calculated using a 3-compartment model and an operational equation that included a k-4. Results: On 6 mornings, we completed 12 18F-FDG quantitative small-animal PET studies on 2 rats. The rats grew steadily before and after the 6 quantitative small-animal PET studies. The CMRglc of the conscious brain (e.g., right parietal region, 99.6±10.2 μmol/100 g/min; n = 6) was comparable to that for 14C-deoxyglucose autoradiographic methods. Conclusion: Maintaining good blood patency in catheterized rats is not difficult. Longitudinal quantitative small-animal PET imaging with an arterial input function can be performed routinely.