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What is MRI Imaging of the Body?

Magnetic resonance imaging (MRI) is a noninvasive, medical test that helps physicians diagnose and treat medical conditions.

Magnetic resonance imaging (MRI) is a noninvasive, medical test that helps physicians diagnose and treat medical conditions.

MR imaging uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of organs, soft tissues, bone and virtually all other internal body structures. The images can then be examined on a computer monitor or printed. MRI does not use ionizing radiation (x-rays).

Detailed MR images allow physicians to better evaluate parts of the body and certain diseases that may not be assessed adequately with other imaging methods such as x-ray, ultrasound or computed tomography (also called CT or CAT scanning).

What are some common uses of the procedure?

MR imaging of the body is performed to evaluate:

  • organs of the chest, abdomen and pelvis—including the heart, lungs, liver, biliary tract, kidney, spleen, and pancreas.
  • pelvic organs including the reproductive organs in the male (prostate and testicles) and the female (uterus and ovaries).
  • pelvic and hip bones.
  • blood vessels (MR Angiography).

Physicians use the MR examination to help diagnose or monitor treatment for conditions such as:

  • tumors of the chest, abdomen or pelvis.
  • coronary artery disease and heart problems including the aorta, coronary arteries and blood vessels, by examining the size and thickness of the chambers of the heart and the extent of damage caused by a heart attack or progressive heart disease. For more information, visit the MR Angiography and Cardiac CT for Calcium Scoring pages.
  • tumors and other abnormalities of the reproductive organs (e.g., uterus, ovaries, testicles, prostate).
  • functional and anatomical abnormalities of the heart.
  • lesions of the liver and other organs (when a complete diagnostic assessment can not be done with other techniques).
  • congenital arterial and venous vascular anomalies and diseases (e.g., atherosclerosis) of the chest, abdomen and pelvis (MR Angiography).
  • biliary system conditions (MRCP).

How should I prepare for the procedure?

To download instructions please click Exam Preparations

You may be asked to wear a gown during the exam or you may be allowed to wear your own clothing if it is loose-fitting and has no metal fasteners.

Guidelines about eating and drinking before an MRI exam vary at different facilities. Unless you are told otherwise, you may follow your regular daily routine and take medications as usual.

Some MRI examinations may require the patient to swallow contrast material or receive an injection of contrast into the bloodstream. The radiologist or technologist may ask if you have allergies of any kind such as hay fever, hives, allergic asthma, or to food or drugs. However, the contrast material used for an MRI exam, called gadolinium, does not contain iodine and is less likely to cause an allergic reaction.

The radiologist should also know if you have any serious health problems and what surgeries you have undergone. Some conditions, such as kidney disease and sickle cell anemia, may prevent you from having an MRI with contrast material.

Women should always inform their physician or technologist if there is any possibility that they are pregnant. Because the risks of an MRI exam to the baby are unknown, pregnant women should not have this exam unless the potential benefit from the MRI is assumed to outweigh the potential risks. See the Safety page for more information about pregnancy and MR imaging.

If you have claustrophobia (fear of enclosed spaces) or anxiety, you may want to ask your physician for a prescription for a mild sedative.

Jewelry and other accessories should be left at home if possible, or removed prior to the MRI scan. Because they can interfere with the magnetic field of the MRI unit, metal and electronic objects are not allowed in the exam room. These items include:

  • jewelry, watches, credit cards and hearing aids, all of which can be damaged.
  • pins, hairpins, metal zippers and similar metallic items, which can distort MRI images.
  • removable dental work.
  • pens, pocketknives and eyeglasses.

In most cases, an MRI exam is safe for patients with metal implants, except for a few types. People with the following implants cannot be scanned and should not enter the MRI area:

  • internal (implanted) defibrillator
  • cochlear (ear) implant
  • clips used on brain aneurysms

You should tell the technologist if you have medical or electronic devices in your body, because they may interfere with the exam or potentially pose a risk. Examples include:

  • artificial heart valves
  • implanted drug infusion ports
  • infusion catheter
  • intrauterine device (IUD)
  • implanted electronic device, including a cardiac pacemaker
  • artificial limbs or metallic joint prostheses
  • implanted nerve stimulators
  • metal pins, screws, plates or surgical staples.

In general, metal objects used in orthopedic surgery pose no risk during MRI. However, a recently placed artificial joint may require the use of another imaging procedure. If there is any question of their presence, an x-ray may be taken to detect the presence of any metal objects.

Sheet metal workers and others who might have metal objects such as shrapnel in their bodies may also require an x-ray prior to an MRI. Dyes used in tattoos may contain iron and could heat up during MRI, but this is rarely a problem. Tooth fillings and braces usually are not affected by the magnetic field but they may distort images of the facial area or brain, so the radiologist should be aware of them.

For more information go to Radiologyinfo.org