Breast imaging-reporting and data system (BI-RADS)

BI-RADS classification is proposed by the American College of Radiology (ACR), last updated in November 2015, and is a widely used classification system at the time of writing this article (July 2016).

The BI-RADS acronym stands for Breast Imaging-Reporting and Data System which is a widely accepted risk assessment and quality assurance tool in mammography, ultrasound or MRI. Part of the initial implementation was to make the reporting of mammograms more standardized and comprehensible to the non-radiologist reading the report.

This is not a unique system. There are other systems (e.g. Nottingham classification) in use all over the world.


The latest version classifies lesions into six categories: 

  • BI-RADS 0
    • incomplete, further imaging or information is required, e.g. compression, magnification, special mammographic views, ultrasound
    • this is also used when requesting previous images not available at the time of reading
  • BI-RADS I: negative, symmetrical and no masses, architectural disturbances or suspicious calcifications present
  • BI-RADS II: benign findings, interpreter may wish to describe a benign-appearing finding
  • BI-RADS III: probably benign, short interval follow-up suggested
  • BI-RADS IV: suspicious abnormality
    • there is a mammographic appearance which is suspicious for malignancy
    • biopsy should be considered for such a lesion
    • these can be further divided as
  • BI-RADS V: there is a mammographic appearance which is highly suggestive of malignancy, action should be taken
  • BI-RADS VI: known biopsy proven malignancy 

The vast majority of screening mammograms fall into BIRADS I or II 4.

Treatment and prognosis

Risk of cancer:

  • BI-RADS III: ~2%
  • BI-RADS IV: ~30% 3
  • BI-RADS V: 95%
Breast imaging and pathology
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Article information

rID: 10003
System: Breast, Oncology
Synonyms or Alternate Spellings:
  • BIRADS classification
  • BIRADS system
  • BIRADS 6 tier system
  • Breast imaging-reporting and data system

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Cases and figures

  • Case 1: BIRADS 0
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    Case 2: BIRADS II
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  • Case 4: BIRADS IV
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  • Case 5: BIRADS IV-V
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  • Case 6: BIRADS V
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  •  Case 7: BIRADS V
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  • Case 8: BIRADS V
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