Breast Imaging Reporting and Data System

BIRADS

Summary of the Breast Imaging Atlas from ACR

• Category 0 - Incomplete, needs additional imaging
• Category 1 - Negative
• Category 2 - Benign findings
• Caregory 3 - Probably benign (<2% chance of malignancy)
• Category 4 - Suspicious abnormality, biopsy should be considered
• Category 5 - Highly suspicious, appropriate action should be taken (>95% chance of malignancy)
• Category 6 - Proven cancer

Masses

A space occupying lesion seen in two projections (asymmetry in single projection).

1. Shape
   1. Round
   2. Oval
   3. Lobular
   4. Irregular
2. Margin - modifies shape
   1. Circumscribed (at least 75% well defined, remainder obscured not suspicious)
   2. Microlobulated
   3. Obscured by superimposed tissue)
   4. Indistinct (ill defined, raises concern for infiltration)
   5. Spiculated
3. Density - most cancers are of higher density than surrounding fibroglandular tissue, although they can trap fat
   1. High Density
   2. Equal Density
   3. Low Density (not fat containing)
   4. Radiolucent (Fat Density) - often benign entities such as oil cyts, lipoma, galactocele, hamartoma, fibroadenolipoma.

Calcifications

1. Typically Benign
   1. Skin Calcifications - often lucent center, tangential views can confirm
   2. Vascular Calcifications - parallel tracks, tubular
   3. Coarse Popcorn-like Calcifications - often casued by involuting fibroadenoma
   4. Large Rod-like Calcifications - a/w ductal extasia, radiate towards nipple, secretory calcs in women > 60 yo
   5. Round Calcifications - benign when scattered, punctate may warrent closer investigation
   6. Lucent Centered Calcifications - thicker than eggshell, oil cyst
   7. Eggshell Calcifications - fat necrosis and calc in wall of cyst
   8. Milk of Calcium Calcifications - sedimented calcs in macro or micro cysts, change with projection
   9. Suture Calcifications
   10. Dystrophic Calcifications - trauma or RT
2. Intermediate Concern / Suspicious Calcifications
   1. Amorphous or Indistinct Calcifications - small and hazy, can't place in another category, get magnification views
   2. Coarse Heterogenous Calcifications - smaller than classic benign dystrophic calcifications, often secondary to fibrosis, fibroadenoma, etc.
3. Higher Probability Malignancy
   1. Fine Pleomorphic Calcifications - fall between Amorphous and Fine Linear
   2. Fine Linear or Branching Calcifications - suggests filling lumen of duct
4. Distribution Modifiers
   1. Diffuse / Scattered - usually bilateral and benign
   2. Regional - involve a quadrant but not a specific duct distibution, usually benign
   3. Grouped or Clustered - at least 5 calcs in a small volume (<1cc)
   4. Linear - suspicious for malignancy
   5. Segmental - worrisome, suggests deposits in ducts and branches

Architechural Distortion

Abnormality w/o mass, suspicious for malignancy or radial scar, recommend biopsy

Special Cases

1. Asymmetric Tubular Structure / Solitary Dilated Duct
2. Intramammary Lymph Node
3. Global Asymmetry
4. Focal Asymmetry - not a well defined mass, but may warrent further evaluation

Associated Findings

1. Skin Retraction
2. Nipple Retraction - can be normal if chronic and bilateral
3. Skin Thickening - often s/p RT or trauma
4. Trabecular Thickening - thickening of the fibrous septa, often post RT
5. Skin Lesion
6. Axillary Adenopathy
7. Architectural Distortion
8. Calcifications

Location

1. Location
   1. Clock Face
   2. Quadrant
   3. Subareolar, Central, Axillary Tail
2. Depth
   1. Anterior
   2. Middle
   3. Posterior

Multicentric - tumor foci within different quadrants, contraindication to breast conservation sugery

Multifocal - tumor foci within the same quadrant of the breast

Breast Composition

1. Almost Entirely Fat (<25% glandular)
2. Scattered Fibrogladular Densities (25-50% glandular)
3. Heterogeneously Dense (50-75% gladular, may obscure small masses)
4. Extremely Dense (>75% glandular, lowers the sensitivity for mammography)