Development of 3T Magnetic Resonance Research Methods for NIA Studies

Background: \- Magnetic resonance imaging (MRI) studies provide important information on the structure and function of various body systems, including the brain, muscles, joints, heart, and blood vessels. Scientific applications of MRI scans often use techniques that need to be modified or refined before they are used in clinical studies. To develop and modify these techniques for the new Philips 3T Achieva whole-body MRI scanner, researchers are interested in conducting trial MRI scans on healthy individuals and individuals with conditions that require imaging studies. Objectives: \- To conduct preliminary trials of the 3T MRI facility to develop and refine MRI scanning procedures. Eligibility: \- Individuals at least 18 years of age who are able to have magnetic resonance imaging. Design: * Participants will be screened with a full medical history and physical examination, as well as blood and urine tests. * Participants will have an MRI scan using the 3T scanner. Some scans may require the use of a contrast agent or radiotracer, which is a small amount of radioactive substance that will be injected before the start of the scan. Some participants may be asked to perform tasks of thinking and movement while in the scanner, in order to test the procedures required for a functional MRI scan. * No treatment will be provided as part of this protocol.