MRI (Magnetic Resonance Imaging)
What is an MRI?
MRI stands for “magnetic resonance imaging” scan. It is a medical test that lets the healthcare provider look at internal organs using magnets and radio waves. A computer then makes a slice-by-slice figure of the patient, like a loaf of bread that has been sliced. MRI scans are used because they give special details that cannot be seen in other radiology tests. A radiologist is a doctor that specializes in looking at different types of images of patients. The radiologist will carefully look at the scan and create a report.
MRI scans are useful for looking at the brain, spinal cord, muscles, bones, the heart, and the liver. MRI scans are most often used for non-emergent reasons. This is because MRI scans take longer to be done and read. MRI scans can be used emergently in cases of stroke.
MRI scans may be done to figure out the size of tumors and whether they can be removed with surgery. MRIs are most often used for:
- Brain and spinal cord tumors.
- Head and neck tumors near the base of the skull.
- Tumors in the chest, particularly near the chest wall or heart.
- Breast cancer patients may have an MRI to check for breast cancer in the other breast.
- MRI may be used in addition to a mammogram in women who have dense breast tissue or are at high risk for cancer.
- Liver cancer.
- Prostate cancer.
How do I prepare for an MRI scan?
Before your MRI, you will be asked to remove any metal on your body. You will be asked a series of questions about any metal you could have in your body. Leave jewelry and other metal at home, if possible. You do not need to fast from eating before the MRI.
How is this test performed?
The patient lies flat on a table and should stay still during the test. Moving can make the MRI results blurry. The table moves through a large tube (this is the magnet). The tube can be loud while it is on and you may be given earplugs to protect your ears. The test can take anywhere from 30 minutes to 2 hours, depending on what areas are being scanned. A radiation technologist will be in a nearby room with a window and microphone to hear and talk to you during the exam.
IV contrast can be used during an MRI to better see the blood vessels. This contrast is known as “gadolinium” and is different from the contrast used in a CT scan. If you have an allergy to CT contrast, which is iodine based, there is a good chance you will still be able to have the MRI contrast. Gadolinium cannot be given to anyone with kidney disease because it can harm the kidneys.
Many people worry about being in a tube during the exam; however, recently, much larger tubes, or bores, are being used. Patients who are claustrophobic (afraid of small or confined spaces) can be given a medicine to relax. You will need to have a ride home after the exam if you have taken a medication to relax, as you will not be able to drive.
For patients who are still not able to tolerate the MRI, "open" MRI scans may be performed. They are not as widely available as a standard MRI. The quality of the pictures from an open MRI may not be as good. You should talk with your provider about your options for MRI.
Picture of an MRI machine
How do you receive the results of your MRI?
The radiologist writes a report for the provider who ordered the MRI. The report provides information about the patient, the reason for the test, if contrast was given and what was found. The report will detail both normal and abnormal findings. Your provider will be able to talk to you about your results.
American Cancer Society. (2019). MRI for Cancer. Retrieved from https://www.cancer.org/treatment/understanding-your-diagnosis/tests/mri-for-cancer.html
U.S. Department of Health and Human Services: National Institutes of Health. (2016). MRI Scans. Retrieved from https://medlineplus.gov/mriscans.html