Women's Health


The term BI-RADS, an acronym in English for Breast Image Reporting and Data System , is a classification developed in 1993 by the American College of Radiology( ACR) in order to standardize mammography reports in order to minimizerisks of misinterpretation of mammography reports and to facilitate the comparison of results for future clinical studies.

Thus, the ACR BI-RADS is a standardized form of reporting the radiological findings of mammography, which greatly reduces the risk of subjective interpretations of purely descriptive reports and prevents the same finding from being interpreted differently between the radiologistwho performed the examination and the attending physician of the patient who requested the examination.

The BI-RADS classification also helps the attending physician to know when investigating a suspected lump should be supplemented with other methods and when it can be satisfactorily discontinued only with the result of the mammogram. It also helps to standardize medical conducts.

Initially proposed as a classification for mammography reports, BI-RADS has also been used to describe mammographic and mammographic breast ultrasound reports.

ACR Classification BI-RADS

If you have a mammogram and have any suspicious lesions, be it a lump, cyst, calcification or a clearly malignant lesion, it is important that the mammogram is as straightforward and understandable as possible. In order for all physicians, regardless of their specialties, to understand and interpret the results of their mammography uniformly, the radiologist needs to synthesize the mammographic findings using one of the six categories of the BI-RADS classification. Through this classification, your doctor can easily distinguish the likelihood of your injury being malignant or benign.

What we will describe below are the 6 BI-RADS classification categories( criteria updated in November 2015 by the American College of Radiology).

BI-RADS category 0 - Inconclusive examination

When the radiologist classifies his result as BI-RADS 0, this means that he considered the examination inconclusive or incomplete. The causes for a BI-RADS 0 include technical factors, such as poor quality images, which may be due to inadequate breast positioning or patient movement during the examination. The BI-RADS 0 can also be assigned when there is doubt about the existence or not of an injury, and it is necessary to perform another image examination to take the test.

The availability of previous mammography reports so that the radiologist can compare old images with current images decreases the risk of mammography being classified as BI-RADS 0. For example, a lesion difficult to evaluate but has existed for several years andnever changed his appearance, speaks clearly in favor of a benign lesion. With the help of previous results, the physician can change the rating from BI-RADS 0 to BI-RADS 2( see below).

When the mammography report receives the BI-RADS classification, the patient is instructed to perform additional mammographic images and / or a breast ultrasound.

Therefore, a BI-RADS 0 does not indicate that the lesion is probably benign or that it is probably malignant. BI-RADS 0 is an inconclusive examination that must be repeated.

BI-RADS category 1 - Normal examination or negative test

When the radiologist classifies your result as BI-RADS 1, this means that the mammogram does not change. The examination is completely normal. The breasts are symmetrical and no masses, architectural distortions or suspicious calcifications were visualized.

The risk of malignant lesion in a test classified as BI-RADS 1 is 0%.

BI-RADS category 2 - Examination with certainly benign findings

When the radiologist classifies his result as BI-RADS 2, this means that he has found some changes in mammography, but that the characteristics of the lesion allow to affirm that it is benign.

Among the lesions that are usually found in BI-RADS 2 classification, we can mention:

  • Calcified Fibroadenomas.
  • Simple breast cysts( read: CISTO AMAMA - Symptoms, Treatment and Risk of Turning Cancer).
  • Intra-mammary lymph nodes.
  • Vascular calcifications.
  • Lipomas.
  • Hamartomas.
  • Calcifications of secretory origin.
  • Silicone Implants.
  • Surgical scar.

To be classified as BI-RADS 2, a physician must be assured that the lesion is of benign origin. If the doctor has questions, the result can not be classified as BI-RADS 2, but rather as BI-RADS 3.

Therefore, in practice, a BI-RADS 2 result has the same clinical value as a BI-RADS 1.The risk of malignant injury is 0%.

BI-RADS category 3 - Examination with probably benign findings

When the radiologist classifies his result as BI-RADS 3, this means that he has found some changes in the mammogram, which is probably benign, but that he does not have 100% safety. Although the physician is almost certain that the lesion is benign, if he has the slightest doubt, the classification should be Bi-RADS 3.

When the examination is classified as BI-RADS 3, the suggested course is to repeat the mammogram after6 months. If the new examination is also BI-RADS 3, a new mammogram is repeated after another 6 months( 12 months after the first).If the result is the same, a last mammographic reassessment should be performed after another 1 year( 2 years after the initial result).If after 2 years, the lesion remains the same, the radiologist may consider BI-RADS 2.

On the other hand, if at any time after the lesion changes characteristics and becomes more suspect, the classification must bechanged to BI-RADS 4 and the lesion should be biopsied. Several studies have already shown that this semi-annual follow-up does not pose a risk for the patient. Even in the rare cases where the lesion changes characteristic and there is a suspicion of malignancy, waiting does not harm the patient's health.

Therefore, a BI-RADS 3 result indicates a lesion with a very low risk of malignancy, which does not need to be initially biopsied, but which, for prudence, should be followed closely over the next 2 years.

The risk of malignant lesion of BI-RADS 3 is only 2%, that is, 98% of cases are even benign lesions.

BI-RADS category 4 - Exam with suspect findings.

When the radiologist rates his result as BI-RADS 4, it means that he has found some alteration in mammography, which may be cancer but is not necessarily cancer. All patients with a BI-RADS 4 result should be submitted to biopsy of the lesion so that the correct diagnosis can be established.

The BI-RADS 4 classification is usually divided into 3 sub-categories according to the risk of cancer:

BI-RADS 4A - Injury with low suspicion of malignancy - 2 to 10% risk of cancer.
BI-RADS 4B - Injury with moderate suspected malignancy - 11 to 50% risk of cancer.
BI-RADS 4C - Injury with high suspicion of malignancy - 51 to 95% risk of cancer.

Regardless of the subcategory of BI-RADS 4, all cases should be biopsied. The difference is that in the patient with BI-RADS 4A, the biopsy is expected to confirm a benign lesion, whereas in BI-RADS 4C, the biopsy is expected to confirm the diagnosis of cancer.

BI-RADS category 5 - Examination with high risk of cancer

When the radiologist classifies his result as BI-RADS 5, this means that he has found some alteration in mammography, which is almost certainly derived from breast cancer.

Breast lesions with typical cancer characteristics include dense and spiculated nodules, pleomorphic calcifications, lesions with skin retraction or distortions of the breast architecture or fine linear calcifications arranged in a segment of the breast.

All BI-RADS 5 lesions should be biopsied.

The risk of malignancy in an examination classified as BI-RADS 5 is greater than 95%.

BI-RADS category 6 - Examination with previously known malignant lesion

The BI-RADS 6 classification is used only in patients who already have the diagnosis of established breast cancer and end up performing a mammogram to follow up the disease, such as after starting chemotherapy. This classification serves only to confirm to the physician that the malignant lesion identified on the mammogram is the same as previously known.