BI-RADS: Standardizing Breast Imaging and Reporting
WHAT IS IT?
BI-RADS: Breast Imaging Reporting and Data System, was developed by the American College of Radiology (ACR) to standardize mammogram reporting, as well as breast ultrasound and MRI reporting.
The standard mammogram report includes the following
- Indication and type of mammogram (screening/diagnostic)
- Statement regarding breast density
- Description of pertinent findings including size and location, oriented by quadrant and clock position
- Summary of important findings and BI-RADS category
KEY POINTS:
BI-RADS Classification Standardizes Findings and Recommendations for Further Management
BI-RADS 0 : Incomplete
- Recall for additional imaging/comparison with prior examinations, or both
BI-RADS 1: Negative (Essentially 0% chance of malignancy)
- Routine screening
BI-RADS 2: Benign (Essentially 0% likelihood of malignancy)
- Routine screening
BI-RADS 3: Probably benign (> 0% but ≤ 2% likelihood of malignancy)
- 6 month follow-up or continued surveillance
BI-RADS 4: Suspicious (> 2% but < 95% likelihood of malignancy)
- 4A: Low suspicion for malignancy (> 2% to ≤ 10% likelihood)
- 4B: Moderate suspicion for malignancy (> 10% to ≤ 50% likelihood)
- 4C: High suspicion for malignancy (> 50% to < 95% likelihood)
- Tissue diagnosis needed for all BI-RADS 4 categories
BI-RADS 5: Highly suggestive of malignancy (95% likelihood of malignancy)
- Tissue diagnosis needed
BI-RADS 6: Known, biopsy proven malignancy
- Surgical excision when appropriate
Density Categories
- Category a: Breasts are almost entirely fatty
- Prevalence: 10% of the population
- Mammography considered highly sensitive in this setting (88%)
- Category b: There are scattered areas of fibroglandular density
- Prevalence: 43% of the population
- Still sensitive but decreased from category a (82%)
- Category c: Breasts are heterogeneously dense
- Prevalence: 39%
- Small masses may be obscured
- Sensitivity drops to 69%
- Note: Breast cancer risk is 1.2 relative risk compared to average breast density
- Category d: Breasts are extremely dense
- Significantly lowers sensitivity of mammography (62%)
- Note: Breast cancer risk is 2.1 relative risk compared to average breast density
Learn More – Primary Sources:
ACOG Practice Bulletin No 164. Diagnosis and Management of Benign Breast Disorders
ACR BI-RADS® Atlas, Breast Imaging Reporting and Data System
ACOG Committee Opinion 625: Management of with Dense Breasts Diagnosed with Mammography