Breast MRI or magnetic resonance imaging of the breast is a non-invasive diagnostic test to show the doctor any abnormality in the breast including breast cancer. This procedure makes the use of powerful magnetic field and radio waves, which pass through the breast tissue and translate into images on the computer screen.

Although this is a sensitive test, it can still miss some cancerous and non-cancerous breast tumors, which a mammogram will detect. They also can’t differentiate between cancerous tissue, cysts, or fibroids. A breast MRI, therefore, does not replace a mammogram but is used along with it.

However, that does not diminish its importance. A breast MRI helps to differentiate between the normal breast tissue and diseased tissue.

According to a recent study, MRI conducted on women who were suspected of breast cancer in one breast, detected cancer in the other breast in about 90% of the cases. Clinical breast exam and mammography had missed out on the cancer of the other breast.

Statistics show that adding MRI to breast cancer screening doubled the figures of breast cancer cases detected.

MRI is also used in breast screening of high-risk women to ensure the presence or absence of breast cancer. Unlike mammograms, MRI can detect tumors in dense breast tissue.

Although the breast MRI primarily focuses on the breasts and the axillary regions, some other structures such as the lung, mediastinum, bony thorax, and upper abdomen are also visualized.

It can also evaluate cancer-related areas such as axillary lymph nodes, skin, and pectoral muscle that help in prognosis.

Sometimes, the diagnostic value of MRI is combined with ultrasound to evaluate the status of lymph node metastasis in breast cancer  

When does the doctor order a breast MRI?

The doctor orders this test when the clinical examination and findings from mammography and ultrasound do not give enough evidence to confirm the nature of the breast abnormality.

It is also done your breast biopsy is positive for cancer. It helps to show how much the disease has spread.

Your doctor may also order this test as a screening tool for detecting breast cancer in women who are at high risk, those who have a strong family history of breast cancer or ovarian cancer and in those who have hereditary breast cancer gene changes such as BRCA1 or BRCA2

Other conditions in which the doctor may order a breast MRI include

  • Your breast implant has ruptured
  • Your breasts are dense and mammograms did not detect a previous breast cancer
  • You exhibit signs of precancerous breast changes, which include atypical hyperplasia or lobular carcinoma in situ along with a strong family history of breast cancer and dense breast tissue
  • You were exposed to radiation treatments to your chest area before age 30 years.

Breast MRI Procedure

The breast MRI usually takes 30 to 60 minutes but can sometimes extend to 90 minutes.

You are asked to remove all belongings such as your watch, necklace, etc. If you have been on hormone replacement therapy or are taking oral contraceptives, you should stop taking them one month before going for an MRI.

For better image clarity, the best time to have a breast MRI done is seven to ten days after the first day of the menstrual cycle.

You are given a hospital gown to wear asked to lie face down on the MRI table. You then slide into the MRI machine chamber. Your breasts are exposed and project downwards through two openings in the platform of the MRI table.

You will hear thumping sounds for a few minutes. Otherwise, the MRI is eventless. It is necessary to lie still during the procedure because any movement can disturb the accuracy of the findings.

The MRI produces slicing images of the breast so that images of the breast tissue can be viewed at different planes of the breast. This can be compared to slices of bread when the loaf is sliced with a knife.

At times, it may be necessary to inject a contrast medium in your vein to get a better contrast between different tissues and a better visualization on the scan report.

After the MRI, you can immediately get up, wear your clothes and belongings and resume your normal duties.

A radiologist will analyze the images seen on the computer screen. He will send a signed report to your primary care physician, who will share the results with you.

MRI disadvantages and risks

  • MRI cannot detect microcalcifications (tiny specks of calcium) in breast tissue, which can be detected by mammograms. Microcalcifications account for half of the malignancies detected by mammograms.
  • Breast MRI is, therefore, most effective when used in conjunction with mammograms and other imaging procedures. It cannot be a replacement for a mammogram.
  • MRI may give a false positive report, which can later be confirmed as nonmalignant on a breast biopsy. This can result in unnecessary anxiety for the patient.
  • The high cost of MRI is sometimes not covered by insurance.
  • You could have a reaction to the contrast dye used. A contrast breast MRI involves the injection of a dye to make the images easier to visualize. You can develop allergic reactions and some serious complications if you have kidney problems.

Safety of Breast MRI

  • Breast MRI is safe for use in an average person. It does not expose you to radiation. The MRI does not use x-rays and therefore, there is no radiation exposure. It creates a magnetic field and radio waves are sent from a scanner.
  • The strong magnetic field is not harmful to you. However, it can cause implanted medical devices to malfunction.
  • Gadolinium is a contrast agent used in magnetic resonance imaging. There is a lot of evidence to show that gadolinium is safe to use except if you are allergic or have kidney disorders.

Contraindications for Breast MRI

People with certain conditions should not undergo an MRI.

  • Any person with metal implants inside the body such as a heart pacemaker, cochlear implant for hearing, implanted insulin pump, cerebral aneurysm clip, implanted orthopedic rods, implanted insulin pump. This is for fear that the magnetic field may dislodge the metal.
  • People with a metallic rod or such device in the spine
  • People with severe heartburn
  • Pregnancy
  • People who have claustrophobia (fear of closed spaces).
  • People who cannot lie on their backs for 30 minutes or more