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 (CMR_glc). <b>Methods:</b> 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 CMR_glc of each brain region was calculated using a 3-compartment model and an operational equation that included a <i>k*</i>_<i>4</i><b>Results:</b> 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 CMR_glc of the conscious brain (e.g., right parietal region, 99.6 ± 10.2 μmol/100 g/min; <i>n</i> = 6) was comparable to that for ¹⁴C-deoxyglucose autoradiographic methods. <b>Conclusion:</b> 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.