Many women are familiar with regular mammograms, but you may be unclear on where a breast MRI fits into the equation. Breast MRIs are different from mammograms and can be used in various ways to help with screening for and diagnosis of breast cancer.
Mammograms are the standard imaging tests for breast cancer screening. They are used to detect abnormal tissue growth in the breast that might be cancerous. During a mammogram, each breast is placed between two imaging plates while pressure is applied. The images are taken from a few angles to see if there are any areas of concern. If something abnormal is detected by the radiologist reviewing the mammogram, they may suggest additional imaging, such as a breast ultrasound or a breast MRI.
An MRI uses a magnetic field and radiofrequency waves to produce images of the breast tissue and is sometimes used in addition to a mammogram to help with screening, diagnosis, and monitoring a known cancer diagnosis. After getting a mammogram, a breast ultrasound or a breast MRI done, you’ll be given a BI-RADS score to represent your results.
When is a Breast MRI Recommended?
Mammograms are the gold standard for breast cancer screening, but breast MRIs are sometimes used as well. It’s not recommended for everyone. However, it’s a good tool for:
Patients Who Are at a High-Risk of Developing Breast Cancer
For some women who are at a higher risk of developing breast cancer, a screening MRI may be recommended. This would involve getting an MRI in addition to your yearly mammogram. MRIs are not recommended to be used alone because they can miss some cancers that a mammogram would detect.
Confirming a Diagnosis of Breast Cancer
If breast cancer is suspected, a breast MRI may be done to help with diagnosis. Usually, a diagnostic mammogram or an ultrasound would be done first, but if those results are not clear enough, an MRI can be done to help confirm. In some cases an MRI Is performed after a breast biopsy to confirm the location of the tumor.
A breast MRI can find cancers that may not be seen on a mammogram, but they can also lead to a false positive by finding things that turn out not to be cancerous. For this reason, MRIs are rarely used in place of a mammogram to screen women who are at an average risk of breast cancer.
What to Expect During a Breast MRI
Breast MRIs are typically performed at a hospital or a clinic with the equipment for this type of imaging. An IV will be placed in your arm so that a contrast material can be injected into your veins. This allows for the images to show areas of abnormality. Contrast materials can vary depending on the facility you go to and the exact reason for the MRI.
You’ll have to lie face down on a table with your breasts placed in two openings on the table to allow for them to not be compressed. The table you lay on will slide into a narrow tube where it will stay while the images are taken. The machine may make some loud clicking and thumping sounds during the exam. Sometimes, you can use earplugs or headphones during the exam to minimize the sounds if they bother you.
You will stay in the narrow tube for the duration of the exam, which will take around 30 to 45 minutes. After the test is complete, you may have to wait while the images are checked to ensure that no additional ones need to be taken.
Getting the Results of Your Breast MRI
After your test is complete, the results will be interpreted by a radiologist. They will describe what was seen as well as determine a BI-RADS score. BI-RADS stands for Breast Imaging Reporting Data System. This system for scoring provides breast cancer specialists with a strategy to rank patient mammograms and other imaging tests to know if there is a cause for concern.
You may never hear about the BI-RADS score if your results are normal and nothing unusual is detected. However, if something abnormal is detected, your doctor may discuss this score with you.
BI-RADS: The Key to Interpretation
The BI-RADS system is used to report the results of mammograms, breast ultrasounds, and breast MRIs. There are two main components to a BI-RADS score:
Your results will fall into one of the following six categories:
Category 0 - Incomplete. This means the images were not clear enough to provide definitive results and additional images will need to be collected.
Category 1 - Negative for Breast Cancer. No abnormal tissue was seen on the images. You can continue on with your regular yearly breast cancer screening.
Category 2 - Benign. A growth or mass may have been seen but it is not cancerous. This could be scar tissue or a tissue change from a previous surgery. Continued monitoring involves regular screening mammograms.
Category 3 - Probably Benign. A category 3 BI-RADS score means that an abnormal growth was found that is likely benign. A follow-up mammogram in 6 months is recommended to check for any changes. If the mass remains stable over two years, then less frequent imaging can be done. This category has a 0% to 2% chance of being cancerous.
Category 4 - Suspicious. This category indicates that the finding is suspicious of cancer. Your doctor will likely recommend following up with a tissue biopsy to confirm a diagnosis. Category 4 also has three subcategories:
4A - This includes findings with a lower likelihood of breast cancer. 2% to 10% chance of cancer
4B - This includes findings with a moderate likelihood of breast cancer. 10% to 50% chance of cancer
4C - This includes findings with a higher likelihood of breast cancer. 50% to 95% chance of cancer
Category 5 - Highly Suggestive of Breast Cancer. Category 5 results indicate that there is a 95% or higher chance of the growth being cancerous. A follow-up tissue biopsy to confirm the diagnosis will be recommended.
Category 6 - Known Malignancy. This category is for tissue that has previously been confirmed to be breast cancer with a biopsy. Such as when a patient who already has undergone cancer treatment has a follow-up imaging scan done to monitor for treatment progress.
The other component of a BI-RADS score is breast density. This looks at the amount of fibrous and glandular tissue the breasts have compared to fatty tissue. The more dense breasts are, the more difficult it is to see abnormal areas on a mammogram. This slightly raises your risk of having breast cancer.
Category A - mostly fatty breast tissue
Category B - areas of dense glandular and fibrous tissue are in the breast
Category C - more of the breast is made of dense glandular and fibrous tissue
Category D - extremely dense breast tissue
The more dense the breast tissue, the harder it is to see masses in the white areas of the mammogram images. This may lead to a discussion about other types of imaging as a part of screening.
Understanding your BI-RADS score helps your doctor determine if there is a need for additional testing, such as a breast biopsy, or other next steps. A score of 1 means that cancer was not seen in the images so regular screenings are recommended. If cancer was already confirmed in a biopsy or other testing before the MRI, the BI-RADS score will be a 6.
Regular breast cancer screening is a life-saving practice. Don't skip it, and encourage eligible loved ones to do the same.
Trustworthy Breast Cancer Diagnoses and Treatment in the Portland-Vancouver Area
If you or a loved one received a breast cancer diagnosis, the team at Compass Oncology is here to support you every step of the way. Our breast cancer specialists will review test results with you and create a personalized treatment plan based on your results, breast cancer stage, hormone receptor status, type of breast cancer, and several other factors. We can also provide a second opinion on treatment plans. Our cancer centers are in Portland, Tigard, and Vancouver.