Background: Magnetic resonance imaging (MRI) is an important non-invasive tool to study and diagnose cardiovascular disease. MRI scanners use strong magnetic fields and radio waves to create pictures of body organs. Researchers want to find better MRI methods and new ways of imaging cardiovascular disease and better understand normal and abnormal cardiovascular and brain function. Researchers are also interested in seeing if gadolinium, the commonly used MRI contrast agent, stays in the body long after the MRI was performed.

Objectives: To develop new methods for imaging the heart and other organs of the body. To describe cardiovascular diseases using newer MRI methods To look at the relationship between cardiovascular disease and cardiovascular risk factors and other organ systems To look for gadolinium deposits in the brain from prior exams.

Eligibility: Healthy people and people with known or suspected cardiovascular disease ages 7 and older may be eligible for this study. Researchers may be particularly interested in those who: * Have suspected or known cardiovascular disease * Were previously exposed to a gadolinium-based contrast agent, * Need to have a heart MRI scheduled * Need a test of the heart or other body part or will be undergoing a future cardiac catheterization

Design: There are multiple arms to the study with optional components; therefore, there are multiple variations as to what an individual participant s experience may involve. Participants will have an MRI scan lasting up to 2 hours. The scanner is a large hollow tube. During the scan, there may be loud knocking and buzzing sounds caused by the scanner. Participants will lie on a table that slides in and out of the tube. Their vital signs may be monitored. Participants may have a test of heart electrical activity using wires connected to pads on the skin. Participants may have blood drawn. Participants may be injected with an MRI contrast agent through a plastic tube inserted in the arm.