2.8. Small Animal PET/CT Imaging Experimental Procedures

In the PET/CT image study, each mouse was injected intravenously with 7.4 ± 1.2 MBq/0.1 mL of [¹⁸F]FDG for assessment of brain glucose metabolism or with 39.5 ± 3.5 MBq/0.2 mL of [¹¹C]Pittsburgh compound-B (PiB) for detection of Aβ deposition. Static images were acquired after injection by the Triumph PET/SPECT/CT imaging scanner (Gamma Medica-Ideas Inc, Northridge, CA, USA). Anesthesia was induced and maintained using 1–1.5% isoflurane and 100% O₂ inhalation through a nose cone, and all efforts were made to minimize suffering. A PET images dataset was then reconstructed using the ordered-subset expectation maximization algorithm with standard-mode parameters and the 2D maximum likelihood expectation maximization algorithm. Subsequently, regional retention and uptake of these radioligands were processed and analyzed with PMOD 3.5 software package (Pmod Technologies, Zurich, Switzerland). The values were reported as standardized uptake values (SUV) which represented the mean activity values for each whole brain or regional uptake, normalized to the injected dose per body weight of each individual animal.