MRI in Breast Cancer- Indications and Procedure

Last Updated on March 18, 2020

Magnetic resonance imaging or MRI of the breast is a painless test procedure that produces clear images of breast tissue.

MRI in breast cancer is used as a supplementary tool for breast cancer screening along with mammography or ultrasound.

Read more about Breast Cancer Screening Test

MRI uses radio waves and a strong magnet to capture detailed images of the inside of the breast. Also, it does not use X-rays meaning that it is radiation free.

Indications of MRI in Breast Cancer

MRI of the breast is used for screening, diagnosis as well as follow up of breast cancer.

It is not a replacement for mammography or ultrasound which are more commonly used for screening of breast cancer. MRI is rather a supplemental tool that has important uses in some specific situations. These include:

Screening breast cancer in high-risk women

These include women who have a strong family history of breast cancer or those who have inherited changes in BRCA1, BRCA2 or other genes. Women having a precancerous breast condition such as in-situ ductal or lobular carcinoma are also considered as those having a high risk for breast cancer. For such women, a screening MRI is recommended along with a yearly mammogram.

Read more about BRCA Gene Mutation and Testing

Since MRI may show abnormality even in the absence of cancer (high false positive), it is generally not a preferred breast cancer screening method for women with average risk. A high false-positive rate results in a woman being subjected to unnecessary additional tests and biopsies

To diagnose and evaluate breast tumors

In some women, especially those with very dense, non-fatty breast, an MRI may be able to detect a small breast mass better than a mammogram or ultrasound.

To determine the extent of cancer once breast cancer has been diagnosed

After breast cancer has been diagnosed, breast MRI may be performed to determine:

The size and extent of cancer
Whether cancer involves the underlying muscles
To look for other tumors in the same breast or the opposite breast.
To look for any enlarged lymph nodes in the armpit.

Read more about Staging of Breast Cancer

However not every woman with breast cancer would need to undergo a breast MRI.

To further evaluate an abnormal lesion seen on mammography

Sometimes a lesion or an abnormality seen on a mammogram or an ultrasound may look suspicious. In such cases, MRI may be done to determine whether the abnormality is actually of concern and should be biopsied or whether to ignore it.

For follow-up of site of surgery after breast cancer treatment

Scarring of tissue after surgery and recurrent cancer can look similar on mammography and ultrasound. If changes near scar tissue are detected by mammography or on physical examination, MRI can help to determine whether the change is normal scarring or due to cancer recurrence.

To assess response to neoadjuvant chemotherapy

In some cases, breast cancer is treated with chemotherapy before surgery. This is called neoadjuvant chemotherapy. This is usually done in cases where the size of the tumor is large and the drugs cause shrinkage of the tumor, thereby making surgery feasible.

In these cases of breast cancer, MRI is often used to monitor the response to chemotherapy and to evaluate the amount of residual tumor still present. This enables to determine the extent of surgery that would be required. MRI has been found to be superior to mammograms or ultrasound for this evaluation.

How to Prepare for Breast MRI Test

No special diet or preparation is needed before an MRI. However specific instructions may be given depending upon the patient’s medical condition.
Before performing the test, the patient is asked to put on clothes that do not have any zippers or metal.
It is important to remove any metal objects present on the body like removable dental work, hair clips, jewelry, body piercings, watches, credit cards, mobile phones, etc.
In case a person is having any medical implant, it is important to inform the radiologist or technologist about the same. The patient should not even enter the MRI scanning room without first being evaluated whether it is safe. Most orthopedic implants pose no risk and are considered safe. However, in the case of certain metallic implants, MRI should not be performed. These include:
- Pacemakers
- MR-incompatible prosthetic heart valves
- Metal coils inside blood vessels
- Clips used on a brain aneurysm
- A cochlear (ear) implant

The magnetic field produced during MRI may cause pacemakers or other devices to malfunction with serious consequences. If clear cut information is not available, such patients may check with the manufacturer whether the implant is compatible with MRI or not.

If the patient is claustrophobic, mild sedation may be given prior to the procedure.
In some cases, patients may have a known allergy to the contrast agent (eg, gadolinium) used in MRI. This information should also be given beforehand to the radiologist or the technologist.
Provide information about any kidney disease. In severe kidney disease, contrast agent gadolinium may not be safe to be administered. The patient may be asked to undergo a blood test to determine whether the kidneys are functioning normally.
For premenopausal women, MRI is usually performed between day 3 to day 14 of the menstrual cycle. The first day of the menstrual bleeding is considered as day one of the cycles. Inform the MRI facility about your menstrual cycle so that the test can be scheduled accordingly.
MRI should not be performed during pregnancy as the contrast gadolinium may pose a risk to the baby.
If the patient is breastfeeding, it is advisable to stop breastfeeding for 24 to 48 hours after the test so that gadolinium gets eliminated from the body and poses no risk to the baby. The patient may choose to pump the milk during this period and discard it.

Procedure of Breast MRI

MRI uses strong magnets instead of radiation to capture detailed, cross-sectional pictures of the body. A computer processes the signals and creates a series of images, each of which shows a thin slice of the body. The images obtained from different angles are studied by the radiologist to arrive at a diagnosis.

After changing into a gown and removing all metallic objects, you will be asked to lie face down on a narrow flat table. Your breasts will fit into a hollow depression in the table, which contains coils that detect magnetic signals from the MRI machine. This entire table then slides into the large circular opening of the scanning machine.
An intravenous (IV) line will be started in the hand or arm for injecting the contrast dye.
Breast MRI is a painless procedure. However, when contrast is injected, you may experience a feeling of coldness, a salty or metallic taste in the mouth, headache, nausea or itching. These effects usually last for a few seconds only.
You will be asked to stay very still while the procedure is being carried out as any movement could cause distortion and affect the quality of the images obtained. Pillows and straps may be used to make you comfortable and prevent movement during the procedure.
You may also be asked to hold your breath for a few seconds during certain parts of the test.
The MRI machine makes loud, thumping or clicking noises as the magnet switches on and off. You may be provided with earplugs or headphones so as to block these unpleasant sounds.
The technologist is present in another room where the scanner controls are located. However, you can constantly see him or her through a window. You can also communicate with the technologist during the procedure and tell about any breathing difficulties, or feelings of uneasiness or any other problem.
The entire procedure takes about 45 minutes to 1 hour.
Once the procedure is over, the table will slide out of the scanner and you will be assisted to get off the table.
The IV line inserted for contrast administration will be removed.

Aftercare

You should get up slowly from the table to avoid any dizziness or lightheadedness which might occur as a result of lying head down for a long time.

You may be monitored for some time after the test to check for any side effects of the contrast such as rash, itching, or difficulty in breathing.

In case sedatives were given before the procedure, you may be asked to rest until their effect goes away. You should also avoid driving after the test in such a case.

Breastfeeding mothers should not breastfeed for 24 to 48 hours after a breast MRI with contrast.

No other special care or dietary restriction is required after breast MRI. You can resume your daily routine and activities unless your doctor advises you against it.

Results

The images obtained are reviewed by a radiologist (a doctor who specializes in imaging techniques) to arrive at a diagnosis. The final result is then sent to your referring doctor who will discuss the test results with you.