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Lumbar MRI scan

Definition

A lumbar magnetic resonance imaging (MRI) scan is a imaging method that uses powerful magnets and radio waves to create pictures of the lower part of the spine. This area is also called the lumbar spine.

An MRI does not use radiation (x-rays).

Single MRI images are called slices. The images can be stored on a computer or printed on film. One exam produces dozens or sometimes hundreds of images.

See also:

Alternative Names

Magnetic resonance imaging - lumbar spine; MRI - lower back

How the test is performed

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

You will lie on a narrow table, which slides into a large tunnel-like tube.

Some exams require a special dye (contrast). The dye is usually 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 most often lasts 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:

  • Brain aneurysm clips
  • Certain types of artificial heart valves
  • 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:

  • Pens, pocketknives, and eyeglasses may fly across the room.
  • Items such as jewelry, watches, credit cards, and hearing aids can be damaged.
  • 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. If you have difficulty lying still or are very nervous, you may be given a medicine to relax you. Too much movement can blur MRI images and cause errors.

The table may be hard or cold, but you can request a blanket or pillow. The machine produces 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 that you can use to help the time pass.

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

Why the test is performed

A lumbar MRI is most commonly done if you have:

  • Low back pain that does not get better after treatment
  • Leg weakness, numbness, or other symptoms that do not improve or get worse

Your doctor may also order a lumbar MRI if you have:

  • Back pain and fever
  • Birth defects of the lower spine
  • Injury or trauma to the lower spine
  • Low back pain and a history or signs of cancer
  • Multiple sclerosis
  • Problems controlling or emptying your bladder

Normal Values

A normal result means your spine and nearby nerves appear normal.

What abnormal results mean

Abnormal results are most commonly due to:

Other abnormal results may be due to:

Consult your health care provider with any questions and concerns.

What the risks are

MRI contains no radiation. To date, 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 to the substance rarely occur. However, gadolinium can be harmful to patients with kidney problems who require dialysis. If you have kidney problems, please tell your health care provider before the test

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

References

Chou R, Qaseem A, Owens DK, Shekelle P; for the Clinical Guidelines Committee of the American College of Physicians. Diagnostic Imaging for Low Back Pain: Advice for High-Value Health Care From the American College of Physicians. Ann Intern Med. 2011 Feb 1;154(3):181-189.

Wilkinson ID, Paley MNJ. Magnetic resonance imaging: basic principles. In: Grainger RC, Allison D, Adam, Dixon AK, eds. Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 5.

Katz JN, Harris MB. Clinical practice. Lumbar spinal stenosis. N Engl J Med. 2008;358(8):818-825. Verified as current

The Spine. In: Grainger RC, Allison D, Adam, Dixon AK, eds. Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 60 verified as current

Curlee PM. Other disorders of the spine. In: Canale ST, Beaty JH. Campbell's Operative Orthopaedics. 11th ed. Philadelphia, Pa: Mosby Elsevier;2007:chap 21.


Review Date: 2/19/2011
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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