How are Breast Imaging-Reporting and Data System (BI-RADS) categories defined in mammography reports?

Updated: Jan 31, 2017
  • Author: Muhammad Neaman Siddique, MBBS; Chief Editor: Eugene C Lin, MD  more...
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The BI-RADS categories are defined as follows:

  • BI-RADS 0: This means that the assessment is incomplete either because of technical factors, or a lesion is not fully evaluated by the standard screening views, or because prior mammograms are unavailable for confirming stability, or a change in a lesion diagnosed on a prior mammogram. The patient is asked to return for additional mammographic views and/or an ultrasound, or prior mammograms are requested.

  • BI-RADS 1: This is a completely negative examination. The woman should continue with screening mammography and clinical breast examination based on screening guidelines.

  • BI-RADS 2: This represents benign findings such as cysts, fibroadenomas, or benign vascular or parenchymal calcifications. Malignancy is not a concern, and routine follow-up is recommended.

  • BI-RADS 3: This represents findings that do not have characteristic benign features, but the likelihood of malignancy is less than 2%. Examples of such findings are parenchymal asymmetry, calcifications, or a nodule that doesn’t have classic benign imaging features. These patients are advised to have follow-up studies at shorter intervals, during which the category may get upgraded if lesions change sufficiently to raise concern for a malignancy or may get downgraded if repeated imaging confirms benignity of the lesion.

  • BI-RADS 4: This represents findings that are suspicious for malignancy.

  • BI-RADS 5: This represents lesions that are highly suggestive for malignancy, such as spiculations, pleomorphic calcifications, and skin retraction.

  • BI-RADS 6: This represents biopsy-proven malignancy in which the mammogram is being performed to either evaluate the contralateral breast or assess response to neoadjuvant chemotherapy.

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