(MRI Scan of the Heart, Cardiac MRI)
Magnetic resonance imaging (MRI) is a diagnostic procedure that uses a combination of a large magnet, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
The MRI machine is a large, cylindrical (tube-shaped) machine that creates a strong magnetic field around the patient. This magnetic field, along with a radiofrequency, alters the hydrogen atoms' natural alignment in the body. Computers are then used to form two-dimensional (2D) images of the heart's structure based on the activity of the hydrogen atoms. Cross-sectional views can be obtained to reveal further details. MRI does not use ionizing radiation, as do X-rays or computed tomography (CT scans).
A magnetic field is created and pulses of radio waves are sent from a scanner. The magnetic field aligns the hydrogen protons in your body along the same vector. The radio waves then knock the protons out of this aligned position. As the nuclei realign back into proper position, they send out radio signals. These signals are received by a computer that analyzes and converts them into an image of the part of the body being examined. This image appears on a viewing monitor. Some MRI machines look like narrow tunnels, while others are more open.
MRI may be used instead of a CT scan in situations where organs or soft tissue are being studied, because with MRI scanning bones do not obscure the images of organs and soft tissues, as does CT scanning.
Other related procedures that may be used to assess the heart include resting or exercise electrocardiogram (ECG), Holter monitor, signal-averaged ECG, cardiac catheterization, chest x-ray, computed tomography (CT scan) of the chest, electrophysiological studies, myocardial perfusion scans, radionuclide angiography, and ultrafast CT scan. Please see these procedures for additional information.
MRI of the heart may be performed for further evaluation of signs or symptoms that may suggest:
There may be other reasons for your doctor to recommend an MRI of the heart.
Because radiation is not used, there is no risk of exposure to ionizing radiation during an MRI procedure.
Due to the use of the strong magnet, MRI cannot be performed on patients with implanted pacemakers, some older intracranial aneurysm clips, cochlear implants, certain prosthetic devices, implanted drug infusion pumps, neurostimulators, bone-growth stimulators, certain intrauterine contraceptive devices, or any other type of iron-based metal implants. MRI is also contraindicated in the presence of some internal metallic objects, such as bullets or shrapnel, as well as surgical clips, pins, plates, screws, metal sutures, or wire mesh.
If you are pregnant or suspect that you may be pregnant, you should notify your health care provider. MRI is generally considered safe in pregnancy; however, especially in the first trimester, you and your doctor should discuss the potential risks and benefits of having the procedure done.
If contrast dye is used, there is a risk for allergic reaction to the dye. Patients who are allergic to or sensitive to medications should notify their doctor. If you have severe kidney disease or are on kidney dialysis, there is a risk of a condition called "nephrogenic systemic fibrosis" from the dye. You should discuss this risk with your doctor prior to the test.
MRI contrast may have an effect on other conditions, such as allergies, asthma, anemia, hypotension (low blood pressure), kidney disease, and sickle cell disease.
Nephrogenic Systemic Fibrosis (NSF) is a very rare but serious complication of MRI contrast use in patients with kidney disease or kidney failure. If you have a history of kidney disease, kidney failure, kidney transplant, liver disease or are on dialysis, you must inform the MRI technologist or radiologist prior to receiving contrast.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.
MRI may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor's practices.
Generally, an MRI follows this process:
While the MRI procedure itself causes no pain, having to lie still for the length of the procedure might cause some discomfort or pain, particularly in the case of a recent injury or invasive procedure, such as surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.
On occasion, some patients with metal fillings in their teeth may experience some slight tingling of the teeth during the procedure.
You should move slowly when getting up from the scanner table to avoid any dizziness or lightheadedness from lying flat for the length of the procedure.
If any sedatives were taken for the procedure, you may be required to rest until the sedatives have worn off. You will also need to avoid driving.
If contrast dye is used during your procedure, you may be monitored for a period of time for any side effects or reactions to the contrast dye, such as itching, swelling, rash, or difficulty breathing.
If you notice any pain, redness, and/or swelling at the IV site after you return home following your procedure, you should notify your doctor as this could indicate an infection or other type of reaction.
Otherwise, there is no special type of care required after a MRI scan of the heart. You may resume your usual diet and activities, unless your doctor advises you differently.
Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.
The content provided here is for informational purposes only, and was not designed to diagnose or treat a health problem or disease, or replace the professional medical advice you receive from your doctor. Please consult your heath care provider with any questions or concerns you may have regarding your condition.
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