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

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BI-RADS (Breast Imaging-Reporting and Data System) is a risk assessment and quality assurance tool developed by American College of Radiology that provides a widely accepted lexicon and reporting schema for imaging of the breast. It applies to mammography, ultrasound, and MRI. This article reflects the 5th edition, published in 2013 1.

Classification

Breast imaging studies are assigned one of six assessment categories based on the most suspicious lesion:

  • BI-RADS 0: incomplete
    • need additional imaging evaluation (additional mammographic views or ultrasound) and/or
    • for mammography, obtaining previous images not available at the time of reading
  • BI-RADS 1: negative
    • symmetrical and no masses, architectural distortion, or suspicious calcifications
  • BI-RADS 2: benign
    • 0% probability of malignancy
  • BI-RADS 3: probably benign
    • <2% probability of malignancy
    • short interval follow-up suggested
  • BI-RADS 4: suspicious for malignancy
    • 2-94% probability of malignancy
    • for mammography and ultrasound, these can be further divided:
      • BI-RADS 4A: low suspicion for malignancy (2-9%)
      • BI-RADS 4B: moderate suspicion for malignancy (10-49%)
      • BI-RADS 4C: high suspicion for malignancy (50-94%)
    • biopsy should be considered
  • BI-RADS 5: highly suggestive of malignancy
    • >95% probability of malignancy
    • appropriate action should be taken
  • BI-RADS 6: known biopsy-proven malignancy 

The vast majority of screening mammograms fall into BI-RADS 1 or 2 4. Screening mammograms with suspicious findings should generally be assigned BI-RADS 0 to indicate a callback for diagnostic evaluation, meaning additional views to confirm and further evaluate the finding.

Radiographic appearance

BI-RADS provides standardized terminology to describe breast imaging findings.

Ultrasound
Tissue composition

These terms are only used in screening ultrasounds and not in the diagnostic setting.

  • homogeneous background echotexture - fat
  • homogeneous background echotexture - fibroglandular
  • heterogeneous background echotexture

See main article on breast echotexture.

Masses
  • shape
    • oval
    • round
    • irregular
  • orientation
    • parallel
    • not parallel
  • margin
    • circumscribed
    • angular
    • microlobulated
    • indistinct
    • spiculated
  • echo pattern
    • anechoic
    • hyperechoic
    • hypoechoic
    • isoechoic
    • heterogeneous
    • complex cystic and solid
  • posterior features
    • no posterior features
    • enhancement
    • shadowing
    • combined pattern
Calcifications
  • calcifications in a mass
  • calcifications outside of a mass
  • intraductal calcifications
Associated features
  • architectural distortion
  • duct changes
  • skin changes
    • skin thickening
    • skin retractions
  • edema
  • vascularity
    • absent
    • internal vascularity
    • vessels in rim
  • elasticity assessment
    • soft
    • intermediate
    • hard
Special cases
  • simple cyst
  • clustered microcysts
  • complicated cyst
  • mass in or on skin
  • foreign body including implants
  • intramammary lymph nodes
  • axillary lymph nodes
  • vascular abnormalities
  • postsurgical fluid collection
  • fat necrosis
Mammography
Breast composition
  • fatty: the breasts are almost entirely fatty
  • scattered fibroglandular: there are scattered areas of fibroglandular density
  • heterogeneously dense: the breasts are heterogeneously dense, which may obscure small masses
  • extremely dense: the breasts are extremely dense, which lowers the sensitivity of mammography

See the main article on breast density.

Masses
  • shape
    • round
    • oval
    • irregular
  • margin
    • circumscribed
    • obscured
    • microlobulated
    • indistinct
    • spiculated
  • density
    • high density
    • equal density
    • low density
    • fat-containing
Calcifications

See main article on breast calcifications.

Other findings
  • architectural distortion
  • asymmetries
    • asymmetry
    • global asymmetry
    • focal asymmetry
    • developing asymmetry
  • intramammary lymph node
  • skin lesion
  • solitary dilated duct
Associated features
  • skin retraction
  • nipple retraction
  • skin thickening
  • trabecular thickening
  • axillary adenopathy
  • architectural distortion
  • calcifications
Location of lesion
  • laterality
  • quadrant and clock face
  • depth
  • distance from the nipple
MRI
Amount of fibroglandular tissue
  • almost entirely fat
  • scattered fibroglandular tissue
  • heterogeneous fibroglandular tissue
  • extreme fibroglandular tissue

See the main article on breast density.

Background parenchymal enhancement
  • level
    • minimal
    • mild
    • moderate
    • marked
  • symmetry
    • symmetric
    • asymmetric
Masses
  • shape
    • round
    • oval
    • irregular
  • margins
    • circumscribed
    • irregular
    • spiculated
  • internal enhancement characteristics
    • homogeneous
    • heterogeneous
    • rim enhancement
    • dark internal septations
Non-mass enhancement
  • distribution
    • focal
    • linear
    • segmental
    • regional
    • multiple regions
    • diffuse
  • internal enhancement patterns
    • homogeneous
    • heterogeneous
    • clumped
    • clustered ring
Other findings
  • focus
  • intramammary lymph node
  • skin lesion
  • ductal precontrast high signal on T1W
  • cyst
  • postoperative collections (hematoma/seroma)
  • post-therapy skin thickening and trabecular thickening
  • non-enhancing mass
  • architectural distortion
  • signal void from foreign bodies, clips, etc.
Associated features
  • nipple retraction
  • nipple invasion
  • skin retraction
  • skin thickening
  • skin invasion
    • direct invasion
    • inflammatory cancer
  • axillary adenopathy
  • pectoralis muscle invasion
  • chest wall invasion
  • architectural distortion
Fat-containing lesions
  • lymph nodes
    • normal
    • abnormal
  • fat necrosis
  • hamartoma
  • postoperative seroma/hematoma with fat
Location of lesion
  • location
  • depth
Kinetic curve assessment / signal intensity/time curve description
  • initial phase
    • slow
    • medium
    • fast
  • delayed phase
    • persistent
    • plateau
    • washout
Implants
  • implant material and lumen type
    • saline
    • silicone
      • intact
      • ruptured
    • other implant material
    • lumen type
      • single
      • double
      • other
  • implant location
    • retroglandular
    • retropectoral
  • abnormal implant contour
    • focal bulge
  • intracapsular silicone findings
  • extracapsular silicone
    • breast
    • lymph nodes
  • water droplets
  • peri-implant fluid

Radiology report

Findings should be identified in the radiology report if they are suspicious, new, enlarging, or more extensive than at prior exams. Findings should be accompanied by a description of their location and an assessment of suspicion for malignancy.

Treatment and prognosis

When used appropriately, the BI-RADS assessment categories accurately reflect their positive predictive value for cancer, which are on average as follows for mammographically identified lesions that underwent biopsy 3:

  • BI-RADS 2: 0%
  • BI-RADS 3: 2%
  • BI-RADS 4: 30%
  • BI-RADS 5: 97%

See also

There are other systems for classifying breast lesions:

  • -</ul><p>The vast majority of screening mammograms fall into BI-RADS 1 or 2 <sup>4</sup>.</p><h4>Radiographic appearance</h4><p>BI-RADS provides standardized terminology to describe breast imaging findings.</p><h5>Ultrasound</h5><h6>Tissue composition</h6><p>These terms are only used in screening ultrasounds and not in the diagnostic setting.</p><ul>
  • +</ul><p>The vast majority of screening mammograms fall into BI-RADS 1 or 2 <sup>4</sup>. Screening mammograms with suspicious findings should generally be assigned BI-RADS 0 to indicate a callback for diagnostic evaluation, meaning additional views to confirm and further evaluate the finding.</p><h4>Radiographic appearance</h4><p>BI-RADS provides standardized terminology to describe breast imaging findings.</p><h5>Ultrasound</h5><h6>Tissue composition</h6><p>These terms are only used in screening ultrasounds and not in the diagnostic setting.</p><ul>

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