EXPLORER PET/CT in Healthy Volunteers

Inclusion Criteria: * Men and women, 18 years of age or older * Willing and able to fast for at least 6 hours before and for the duration of the scan * Willing and able to lay motionless in a supine position for 60 and 20 minutes at separate timepoints. * Willing and able to give informed consent Exclusion Criteria: * No Primary Care Physician * Body weight \>240 kg * Allergy to iodine contrast (only for subjects enrolled in Arm 3) * Creatinine levels \> 1.5 mg/dL or estimated glomerular filtration rate (eGFR) \< 60 ml/minute (only for subjects enrolled in Arm 3) * Recent (1 month) contrast enhanced CT * Any known concomitant acute infection (including upper respiratory infection, genitourinary infections, etc. * History of metastatic or newly (last 5 years) diagnosed locally invasive cancer. * Chemotherapy in the last 5 years * Radiation therapy in the last 3 years * Major surgery within the last 6 months. * Pregnancy or breast-feeding * Diabetes * Fasting blood glucose level \> 160 mg/dL before administration of FDG * Prisoners * The standard MRI contraindications apply, including but not limited to: Having a pacemaker or other implanted electronic device. Metal foreign bodies, aneurysm clips, heart valve prosthesis, vascular stents, cochlear implants, embolization coils, gunshot wounds with retained bullet fragments, penile implant, IUCD. Claustrophobia