Evaluation of Attenuation Correction Accuracy in Positron Emission Tomography-Magnetic Resonance Imaging (PET-MRI)

Inclusion Criteria: * Participant must be ≥ 18 years of age * Participant can be a male or a non-pregnant female. * Successful completion of MRI screening form * Participant must have undergone a PET/CT examination with injection of a standard dose of 18F-fluorodeoxyglucose (FDG) or other PET tracer with a half-life greater than one hour either for clinical or research purposes within 3 hrs of the proposed PET-MRI examination. * Participant will be fully informed and has personally signed and dated the written Informed Consent and Health Insurance Portability and Accountability Act (HIPAA) provisions Exclusion Criteria: * Subjects for whom exposure to a strong magnetic field would be a health risk (e.g., subjects with cardiac pacemakers or non-MR compatible metallic implants) * Women who are pregnant. * Subjects who require sedation to participate will be excluded. * Patient/participant has a medical condition which in the judgment of the investigator might make supine positioning for the duration of the scan unsafe, such as (but not limited to) congestive heart failure or significant pulmonary disease.