Breast imaging-reporting and data system (BI-RADS)
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.
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Classification
Breast imaging studies are assigned one of seven assessment categories:
-
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
When there are multiple findings, the BI-RADS category for the exam is assigned the highest category in the following hierarchy, from lowest to highest: 1, 2, 3, 6, 0, 4, 5.
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 (in comparison to subcutaneous fat)
- anechoic
- hyperechoic
- hypoechoic
- isoechoic
- heterogeneous
- complex cystic and solid
- posterior features
- no posterior features
- enhancement
- shadowing
- combined pattern
See main article on breast masses.
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
- arteriovenous malformations/pseudoaneurysms
- Mondor disease
- 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
See main article on breast masses.
Calcifications
- typically benign
-
suspicious morphology
- amorphous
- coarse heterogeneous
- fine pleomorphic
- fine linear or fine-linear branching
- distribution
- diffuse
- regional
- grouped
- linear
- segmental
See main article on breast calcifications.
Other findings
- architectural distortion
-
asymmetries
- asymmetry
- focal asymmetry
- developing asymmetry
- global 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
See main article on background parenchymal enhancement.
Masses
- shape
- round
- oval
- irregular
- margins
- circumscribed
- irregular
- spiculated
- internal enhancement characteristics
- homogeneous
- heterogeneous
- rim enhancement
- dark internal septations
See main article on breast masses.
Non-mass enhancement
- distribution
- focal
- linear
- segmental
- regional
- multiple regions
- diffuse
- internal enhancement patterns
- homogeneous
- heterogeneous
- clumped
- clustered ring
See main article on non-mass enhancement.
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
See main article on breast MRI enhancement curves.
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:
