Summary: The Center for Molecular and Genomic Imaging (CMGI) provides small animal imaging services for preclinical research. Contrast agents are a prerequisite for scientifically useful imaging studies involving microPET and microSPECT. In some studies, a contrast agent is also necessary for microCT imaging studies. Contrast agents include iodine-based compounds for x-ray computed tomography (CT), gadolinium for magnetic resonance imaging (MRI), and radioactive tracers for positron emission tomography (PET) and single photon emission computed tomography (SPECT).