A chest MRI (magnetic resonance imaging) scan is an imaging test that uses powerful magnetic fields and radio waves to create pictures of the chest (thoracic area). It does not use radiation (x-rays).
The test is done in the following way:
Some exams require a special dye called 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. A blood test to measure your kidney function may be done before the test. This is to make sure your kidneys are healthy enough to filter the contrast.
During the MRI, the person who operates the machine will watch you from another room. The test most often lasts 30 to 60 minutes, but it may take longer.
You may be asked not to eat or drink anything for 4 to 6 hours before the scan.
Tell your doctor if you are claustrophobic (afraid of closed spaces). You may be given a medicine to help you feel sleepy and less anxious. Your doctor may suggest an "open" MRI, in which the machine is not as close to your body.
Before the test, tell your health care provider if you have:
The MRI contains strong magnets, so metal objects are not allowed into the room with the MRI scanner. This is because there is a risk that they will be drawn from your body toward the scanner. Examples of metal objects you will need to remove are:
An MRI exam causes no pain. If you have trouble lying still or are very nervous, you may be given medicine to relax you. Too much movement can blur MRI images and cause errors when the doctor looks at the images.
The table may be hard or cold, but you can ask for 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 medicines.
A chest MRI provides detailed pictures of tissues within the chest area.
A chest MRI may be done to:
A normal result means your chest area appears normal.
An abnormal chest MRI may be due to:
MRI uses 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 people with kidney problems who need dialysis. If you have kidney problems, tell your provider before the test.
The strong magnetic fields created during an MRI can cause heart pacemakers and other implants not to work as well. It can also cause a piece of metal inside your body to move or shift.
Currently, MRI is not considered a valuable tool for spotting or monitoring slight changes in lung tissue. The lungs contain mostly air and are hard to image. CT scan tends to be better for monitoring these changes.
Disadvantages of MRI include:
Reviewed By: Denis Hadjiliadis, MD, MHS, Paul F. Harron, Jr. Associate Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.