Current studies demonstrated that the utility of PET/CT/MRI with 2-[18F]BzAHA for quantitative imaging of SIRT1 expression–activity is well-established and characterized in i.c. 9L allograft models in rats and expanded our previous studies on imaging SIRT1 expression–activity in the normal brain.45,52 The level of expression–activity of SIRT1 in 9L gliomas was significantly higher than in the brainstem, contralateral cortex, cerebellum, nucleus accumbens, and hippocampus, as evidenced by both SUV and DV of 2-[18F]BzAHA. Here, SIRT1 is linked to central nervous system cancer.