MRI (magnetic resonance imaging) is a noninvasive procedure that uses powerful magnets and radio waves to produce clear, cross-sectional or three-dimensional images of the body’s tissues. Images can be obtained even through bone and other obstructions.

Because of its safety and clarity, experts consider MRI to be a valuable tool that can aid in the diagnosis of a wide range of conditions, including internal injuries, joint and bone disorders and various diseases, such as arthritis, fibromyalgia and cancer. The only preparation for an MRI involves removing all objects containing metal (e.g., jewelry dentures, wigs) from the body.

MRI is used to detect abnormalities or problems in nearly every part of the body. Because the MRI test relies on a large magnetic field, certain people should avoid the test. These include patients with implanted pacemakers and implantable cardioverter defibrillators (ICDs). Patients with certain other medical implants should consult a physician to find out if an MRI is allowed. In all cases, patients should inform the physician or technician of any metal objects present in their bodies.

Pregnant women should generally avoid MRIs because the risk to the fetus is unknown. However, there may be some instances when an MRI is warranted in pregnant patients.

Patients who are nervous in small spaces may wish to ask their physician about the possibility of receiving a sedative during the procedure, which may take up to one hour or longer in a rather tight space. For some patients using a less enclosed type of MRI machine may be another option.

Patients who receive a sedative will need someone to drive them home from the test. Otherwise, patients are free to return to daily activities after the test is completed.