Best Practices for Preclinical F-18-FDG PET Imaging

1155 Objectives: Preclinical PET imaging can present challenges to new users as quantitative imaging depends on proper study design and animal preparation. As patients are given a list of “do’s” and don’ts” for clinical PET scans, we aim to provide comprehensive guidance to small animal PET imaging. In this study we discuss the use of the most common PET radiotracer, 18F-FDG, to visualize glucose metabolism in healthy and tumor bearing mice. Several parameters were tested in a typical imaging workflow and the results compared to better elucidate the best practices for preclinical 18F-FDG imaging. In particular, this study illustrates several important preparation factors that have a great impact on tracer biodistribution and image quality. These parameters include (1) fasted versus non-fasted animals prior to radiotracer injection, (2) variation in ambient temperature during radiotracer uptake, (3) conscious versus unconscious tracer uptake, (4) tracer injection route, (5) injected activity and (6) anesthesia type. For optimal image quality, new users of this technology should be aware of these parameters when designing and performing PET imaging studies. Methods: 6-8 week old C57/BL6 or nu/nu female mice were used with and without flank subcutaneous inoculation of 2x106 4T1 RedFluc cells (10-14 days for tumor growth). Mice underwent various imaging conditions including 8-12 hours of fasting or non-fasting; subcutaneously (SQ), intraperitoneal (IP) or intravenously (IV) tracer injections; inhalation 1.5% isoflurane mixed with oxygen (ISO) or injectable ketamine/xylazine (KX) anesthesia; various radiotracer activity injections ranging between 24-800 uCi. The animals were all imaged using a 10 min static imaging protocol followed by a standard CT scan post-injection. All preclinical imaging and optimization was performed using a preclinical PET/CT scanner (G8 PET/CT, PerkinElmer Inc., Hopkinton, MA). All organ quantitative image analysis was performed using the VivoQuant software package (inviCRO, Boston, MA). Results: Optimization of the imaging conditions for 18F-FDG PET revealed a variety of ways to improve image quality. 18F-FDG uptake in the heart, brown fat and bowels was significantly (p