An MRI scan is a medical test that uses a magnetic field and radio waves to create a detailed picture of organs and other structures inside the body. MRI stands for magnetic resonance imaging.
The U.S. National Library of Medicine notes that MRI scans are painless. However, some scans take a long time, during which the patient must remain still. This is sometimes uncomfortable.
MRI scans are useful for diagnosing conditions such as torn ligaments and tumors and are especially valuable for examining the brain and spinal cord. Since an MRI scan uses a magnetic field, it is important for the patient to inform his health care professional if he has pieces metal in his body, such as from shrapnel or a bullet injury. It is also necessary for the patient to mention any implanted devices, such as pacemakers or artificial joints.