Breast Imaging Reporting and Data System (BI-RADS)

Understanding your mammogram or breast ultrasound report


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The Breast Imaging Reporting and Data System (BI-RADS) is a numerical scale ranging between zero and six that is used in mammogram, breast ultrasound, and breast magnetic resonance imaging (MRI) reports.

BI-RADS is a standardized way to report your risk of breast cancer based on your diagnostic tests. A change in the number can help your doctors communicate whether your breast images have changed from one test to another.

Breast Imaging Reports

A mammogram is the most common breast imaging test, and it is often used in breast cancer screening. A breast ultrasound or breast MRI can also help identify breast cancer, and these tests are often ordered when further evaluation is needed after a mammogram is reviewed.

Breast imaging reports typically consist of a description of your breast density and any abnormalities in your breasts or in the surrounding area. The report will include the size, location, shape, and any other characteristics of a breast mass (or masses). Your breast imaging may be compared to previous images, especially if you have ever had a concerning mass in the past.

One section on your report also includes the BI-RADS score, which indicates the radiologist's opinion about the absence or presence of breast cancer. Your score gives an idea about your diagnosis and whether you need additional testing.

Your BI-RADS score is helpful, but your breast health and cancer risk can't always be categorized into one of the six categories.

Getting Your Results

Many people think of mammograms and other breast imaging studies as being "yes-no" types of tests. That is not the case, as there are many in-between or gray areas when it comes to breast imaging studies.

Many hospital systems now have patient portals, where you can access your test results even before you get a call from your doctor. This can be a great way for you to stay on top of your health, and to advocate for your own health care.

While you may want to quickly find your BI-RADS number and make a conclusion about your health based on this number alone, it is vitally important that you discuss your results with your doctor—even if your breast imaging test turns out negative (a good result with no sign of breast cancer).

BI-RADS Classifications

Your BIRAD score is a number between zero and six. Each number corresponds to a classification that estimates your breast cancer risk based on the imaging test. The individual categories are described here, and the table below provides a quick summary.

Category 0: Incomplete

A score of zero means that your mammogram or ultrasound didn't provide enough information for a clear diagnosis. This does not necessarily mean your doctor is worried about breast cancer.

This designation requires a follow-up imaging study, such as a mammogram or ultrasound obtained with special views or a breast MRI. Your report may be classified with a zero rating if a palpable breast lump isn't imaging clearly, if scar tissue from a previous biopsy or surgery is interfering with the image, or if your breasts are dense.

Category 1: Normal
A score of one means that you do not have any suspicious masses or calcifications and your breast tissue looks healthy.

Category 2: Benign
A score of two is given when your breasts are the same size and shape, and your breast tissue looks normal. Any cysts, fibroadenomas, or other masses appear benign.

A score of one or two does not mean that you are not at risk for breast cancer or could not have breast cancer. If your mammogram score is in this category, it is still important to continue regularly scheduled self-breast exams, medical breast exams, and mammograms.

Category 3: Probably Benign
A score of three is assigned when there are no suspicious lesions, masses, or calcifications seen, but a follow-up is recommended to confirm that no cancer exists is recommended. This may be needed if your radiologist does not have your baseline or a previous mammogram for comparison. Category 3 is the most difficult BI-RADS score when it comes to planning subsequent evaluation.

Category 4: Possibly Malignant
A score of four is reported when there are one or more suspicious lesions, masses, or calcifications. Usually, a breast biopsy is recommended to check the suspicious area.

Category 5: Malignant
A score of five means that there is a mass (or more than one mass) with an appearance of cancer. A biopsy is recommended to make an accurate diagnosis.

It's important to note that even though this category is described as "malignant" there are masses which can appear like cancer but which are related to a benign process instead. Conditions such as adenosis, fat necrosis, radial scars, and mastitis can sometimes mimic cancer on a mammogram.

Category 6: Malignant Tissue

Category 6 is only used if tissue from a biopsy has been examined and found to be cancerous. If this is the case, treatments such as surgery, chemotherapy, and/or radiation are required, and the imaging test is being obtained as part of the treatment or follow up plan.

BIRADS Scores Table

Category Diagnosis Number of Criteria
0 Incomplete Your mammogram or ultrasound didn't give the radiologist enough information to make a clear diagnosis; follow-up imaging is necessary
1 Negative There is nothing to comment on; routine screening recommended
2 Benign A definite benign finding; routine screening recommended
3 Probably Benign Findings that have a high probability of being benign (>98 percent); six-month short interval follow-up
4 Suspicious Abnormality Not characteristic of breast cancer, but reasonable probability of being malignant (3 to 94 percent); biopsy should be considered
5 Highly Suspicious of Malignancy Lesion that has a high probability of being malignant (>= 95 percent); take appropriate action
6 Known Biopsy Proven Malignancy Lesions known to be malignant that are being imaged prior to definitive treatment; assure that treatment is completed

Limitations of the BI-RADS Score

It's important to note that your BIRADS score doesn't replace your physician or radiologist's opinion and insight about your imaging tests, and the number is not a substitute for a clinical exam.

Some breast images do not fit neatly into BI-RADS categories, and there may be a wide variety of findings even within the categories.

For younger women, children, and adolescents, the BI-RADS score may not be reliable.

A Word From Verywell

The BI-RADS score is a useful way to compare and standardize breast imaging studies. Yet, it is only one of the many tools that your medical team uses to assess your health.

Your own individual breast cancer risk depends on a number of factors, such as your medical history (if you had cancer in the past) and your family history of cancer and breast cancer. Lifestyle factors, such as smoking and hormone therapy also increase your risk.

Nevertheless, screening mammograms are considered the most effective way to identify early-stage breast cancer and to get the most timely and definitive treatment, so it is important that you get your recommended screening tests (and follow up tests when they are recommended).

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