Magnetic Resonance Imaging (MRI)

MRIs use strong magnetic fields and radio waves, instead of radiation, to create three-dimensional images and two-dimensional cross-sections of the heart. The images produced by MRIs are similar to X-ray images but show more detail of the soft tissues of the body.

Choose another disease or condition... Allergic Rhinitis Allergies, Food Allergy & Asthma Center Alzheimer's Disease Anxiety Aortic Aneurysms Arrhythmia Arthritis, Osteo- (OA) Arthritis, Rheumatoid (RA) Asthma Atopic Dermatitis Attention Deficit Hyperactivity Disorder (ADHD) Back Pain Brain Tumor Bones, Joints & Muscles Center Breast Cancer Brain & Behavior Center Brain Tumor Cancer Center    Brain Tumor    Breast Cancer    Cancer Prevention    Clinical Trials    Colorectal Cancer    Endometrial Cancer    Living With and Beyond Cancer    Lung Cancer    Prostate Cancer    Skin Cancer Cardiomyopathy Cataracts Cholesterol Control Clinical Trials Chronic Obstructive Pulmonary Disease (COPD) Colorectal Cancer Congenital Heart Disease Congestive Heart Failure (CHF) Coronary Artery Disease (CAD) Crohn's Disease Depression Diabetes Center Diabetes, Type 1 Diabetes, Type 2 Digestive Disorders Center Eczema Endometrial Cancer Erectile Dysfunction (ED) Eye & Vision Center Fibromyalgia Food Allergies Gallstone Disease Gastroesophageal Reflux Disease (GERD) GERD Glaucoma Hay Fever Headache Heart Center Hepatitis A Hepatitis B Hepatitis C High Blood Pressure Hypertension Hypertrophic Cardiomyopathy (HCM) Impotence Insomnia Irritable Bowel Syndrome (IBS) Living With and Beyond Cancer Losing Weight Lung Cancer Macular Degeneration Memory Loss Osteoarthritis (OA) Osteoporosis Parkinson's Disease Peptic Ulcer Prediabetes Prostate Cancer Respiratory Disorders Center Restless Legs Syndrome (RLS) Rheumatoid Arthritis (RA) Sexual & Reproductive Health Center Sinusitis Skin Cancer Sleep Apnea Sleep Center Stroke Type 1 Diabetes Type 2 Diabetes Ulcerative Colitis (UC) Weight Control View All Diseases and Conditions More information on Cardiomyopathy is available at these websites recommended by the U.S.News & World Report Library. What is your heart risk? Use our calculator to find out. See the top five online resources for heart information Cardiomyopathy-Related Clinical Trials Information Email this page Print this section

An MRI machine has a large tube that is big enough to accommodate a patient lying down inside. Radio waves and strong magnetic fields are generated inside the shell of the tube and directed toward the body during an MRI scan. The body responds by emitting weak energy signals that are detected by the MRI machine. A computer converts these signals into three-dimensional images of the heart that can be manipulated to show any two-dimensional cross section.

Before the test, you must remove all accessories and clothing containing metal, including jewelry, metal fasteners, dentures, wigs, and hearing aids. Metal objects may interfere with the magnetic field of the MRI, affecting the quality of the image.

An MRI exam is painless and generally lasts between 30 and 60 minutes. The procedure involves lying on a table that slides into the tube. Movement can blur the images, so it is important to lie still. The space inside the tube is quite narrow, and some patients may feel claustrophobic. Often patients will be offered headphones or earplugs to help block out the loud tapping and thumping sounds made by the MRI machine and to help them relax.

Magnetic resonance angiography (MRA) is one of the newer uses of MRI. For this test, a contrast agent, similar to a dye, is injected into the arm or leg through an intravenous line. The contrast agent makes it easier to visualize the heart and blood vessels. One advantage of the MRA is that the contrast agents are less likely to cause allergic reactions than those used during computed tomography (CT or CAT scans).

There are no known risks from the magnetic fields and radio waves produced by MRI machines. However, people who have pacemakers, cardioverter defibrillators, or other metal-containing objects inside their bodies cannot get MRIs. Also, the affects of magnetic fields on fetuses are not well understood, so getting an MRI may not be advisable for pregnant women.