How the test is performed

You may be asked to wear a hospital gown or clothing without metal zippers or snaps (such as sweatpants and a t-shirt). Certain types of metal can cause blurry images.

You will lie on a narrow table. The table slides into a large tunnel-shaped scanner.

Some exams require a special dye (contrast). Most of the time, the dye is given before the test through a vein (IV) in your hand or forearm. The dye helps the radiologist see certain areas more clearly.

During the MRI, the person who operates the machine will watch you from another room. The test lasts about 30-60 minutes, but may take longer.

How to prepare for the test

You may be asked not to eat or drink anything for 4 - 6 hours before the scan.

Tell your doctor if you are afraid of close spaces (have claustrophobia). You may be given a medicine to help you feel sleepy and less anxious, or your doctor may suggest an "open" MRI, in which the machine is not as close to the body.

Before the test, tell your health care provider if you have:

• Artificial heart valves
• Brain aneurysm clips
• Heart defibrillator or pacemaker
• Inner ear (cochlear) implants
• Kidney disease or dialysis (you may not be able to receive contrast)
• Recently placed artificial joints
• Certain types of vascular stents
• Worked with sheet metal in the past (you may need tests to check for metal pieces in your eyes)

Because the MRI contains strong magnets, metal objects are not allowed into the room with the MRI scanner:

• Items such as jewelry, watches, credit cards, and hearing aids can be damaged.
• Pens, pocketknives, and eyeglasses may fly across the room.
• Pins, hairpins, metal zippers, and similar metallic items can distort the images.
• Removable dental work should be taken out just before the scan.

How the test will feel

An MRI exam causes no pain. You may get medicine to relax you if you have a problem lying still or are very nervous. Moving too much can blur MRI images and cause errors.

The table may be hard or cold, but you can ask for a blanket or pillow. The machine makes loud thumping and humming noises when turned on. You can wear ear plugs to help reduce the noise.

An intercom in the room allows you to speak to someone at any time. Some MRIs have televisions and special headphones to help you time pass.

There is no recovery time, unless you were given a medicine to relax. After an MRI scan, you can go back to your normal diet, activity, and medicines.

Why the test is performed

An abdominal MRI provides detailed pictures of the belly area from many views. It is often used to clarify findings from earlier x-rays or CT scans.

This test may be used to look at:

• Blood flow in the abdomen
• Blood vessels in the abdomen
• The cause of abdominal pain or swelling
• The cause of abnormal blood test results, such as liver or kidney problems
• Lymph nodes in the abdomen

MRI can distinguish tumors from normal tissues. This can help the doctor know more about the tumor such as size, severity, and spread. This is called staging.

MRI is sometimes used to avoid the dangers of angiography, too much radiation exposure, and allergies from iodine. 

What abnormal results mean

An abnormal result may be due to:

• Abscess
• Acute tubular necrosis
• Cancer
• Enlarged spleen or liver
• Gallbladder or bile duct problems
• Gallstones, bile duct stones
• Hemangiomas
• Hydronephrosis (kidney swelling from the backflow of urine)
• Kidney infection
• Kidney damage
• Lymphadenopathy (abnormalities of the lymph nodes)
• Obstructed vena cava
• Pancreatic cancer
• Portal vein obstruction (liver)
• Renal arterial obstruction
• Renal vein thrombosis
• Transplant rejection
• Tumor of the gallbladder

Additional conditions under which the test may be performed:

• Abdominal aortic aneurysm
• Acute renal failure
• Adenomyosis
• Atheroembolic renal disease
• Carcinoma of the renal pelvis or ureter
• Chronic renal failure
• Cystinuria
• Hydatidiform mole
• Injury of the kidney and ureter
• Insulinoma
• Islet of Langerhans' tumor
• Medullary cystic disease
• Multiple endocrine neoplasia (MEN) II
• Multiple endocrine neoplasia (MEN) I
• Nephrolithiasis
• Ovarian cancer
• Pheochromocytoma 

What the risks are

MRI does not use ionizing radiation. No side effects from the magnetic fields and radio waves have been reported.

The most common type of contrast (dye) used is gadolinium. It is very safe. Allergic reactions rarely occur. However, gadolinium can be harmful to people with kidney problems who need dialysis. Tell your health care provider before the test if you have have kidney problems.

The strong magnetic fields created during an MRI can cause heart pacemakers and other implants not to not as well. The magnets can also cause a piece of metal inside your body to move or shift.

References

1. Kim DH, Pickhard PJ. Diagnostic imaging procedures in gastroenterology. In: Goldman L, Schafter AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 135.
2. Wilkinson ID, Paley MNJ. Magnetic resonance imaging: basic principles. In: Adam A, Dixon AK, eds. Granger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone;2008:chap 5.

Review Date: 11/9/2012.

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.