Unlike a mammogram, which uses X-rays to create images of the breast, breast MRI uses magnets and radio waves to produce detailed 3-dimensional images of the breast tissue. Before the test, you may need to have a contrast solution (dye) injected into your arm through an intravenous line. Because the dye can affect the kidneys, your doctor may perform kidney function tests before giving you the contrast solution. The solution will help any potentially cancerous breast tissue show up more clearly. Some people experience temporary discomfort during the infusion of the contrast solution.
Cancers need to increase their blood supply in order to grow. On a breast MRI, the contrast tends to become more concentrated in areas of cancer growth, showing up as white areas on an otherwise dark background. This helps the radiologist determine which areas could possibly be cancerous. More tests may be needed after breast MRI to confirm whether or not any suspicious areas are actually cancer.
For the breast MRI, you will need to pull down your hospital gown to your waist or open it in front to expose your breasts. Then you lie on your stomach on a padded platform with cushioned openings for your breasts. Each opening is surrounded by a breast coil, which is a signal receiver that works with the MRI unit to create the images. The platform then slides into the center of the tube-shaped MRI machine. You won’t feel the magnetic field and radio waves around you, but you will hear a loud thumping sound. You will need to be very still during the test, which takes around 30 to 45 minutes. If you’re claustrophobic, being confined within an MRI machine for a long period of time can be difficult. Some facilities have an open MRI machine to avoid this problem, or you may be given a mild sedative.
Because the technology uses strong magnets, it is essential that you remove anything metal — jewelry, snaps, belts, earrings, zippers, etc. — before the test. The technologist also will ask you if you have any metal implanted in your body, such as a pacemaker or artificial joint.
Where to have breast MRI
It’s important to have breast MRI done at a facility with:
- MRI equipment designed specifically for imaging the breasts. Not all hospitals and imaging centers have this; instead, many have MRIs used for scanning the head, chest, or abdomen.
- The ability to perform MRI-guided breast biopsy. If the breast MRI reveals an abnormality, you’ll want to have an MRI-guided breast biopsy (a procedure to remove any suspicious tissue for examination) right away. Otherwise, you’ll need to have a breast MRI again at another facility that offers an immediate MRI-guided breast biopsy.
If your doctor recommends that you have breast MRI for screening, diagnosis, or follow-up, ask for help in finding the best place to have the test done. The American College of Radiology is working on a system for accrediting breast MRI centers, which should make it easier to find high-quality breast MRI facilities in the future.