Breast · Breast imaging reporting systems · BI-RADS v2025
BI-RADS Assessment Categories
American College of Radiology BI-RADS final assessment categories linking breast imaging findings with malignancy likelihood and management.
Purpose
To standardise the final assessment of breast imaging findings and communicate the corresponding malignancy likelihood and management recommendation.
| Category | Assessment | Likelihood of malignancy | Usual management |
|---|---|---|---|
| 0 | Incomplete | Not applicable | Additional imaging evaluation and/or comparison with prior examinations |
| 1 | Negative | No suspicious finding | Routine screening |
| 2 | Benign | Benign finding | Routine screening |
| 3 | Probably benign | >0% to ≤2% | Short-interval imaging follow-up |
| 4A | Low suspicion for malignancy | >2% to ≤10% | Tissue diagnosis should be considered |
| 4B | Moderate suspicion for malignancy | >10% to ≤50% | Tissue diagnosis should be considered |
| 4C | High suspicion for malignancy | >50% to <95% | Tissue diagnosis should be considered |
| 5 | Highly suggestive of malignancy | ≥95% | Tissue diagnosis and appropriate clinical action |
| 6 | Known biopsy-proven malignancy | Malignancy already established histologically | Manage as a known malignancy |
How to use it
- The BI-RADS category is the final assessment and must be accompanied by a concordant management recommendation.
- Category 0 indicates an incomplete evaluation; it is not a category of malignancy suspicion.
- Category 3 should be used only for an appropriately characterised probably benign finding after complete diagnostic evaluation, not for an indeterminate lesion.
- Category 4 spans a broad risk range and is subdivided into 4A, 4B and 4C to communicate increasing suspicion.
- Category 6 is reserved for imaging performed after histological confirmation of malignancy and before definitive treatment.
Common mistake
Do not interpret category 6 as merely more suspicious than category 5: category 5 is highly suggestive but not yet proven, whereas category 6 requires an established biopsy diagnosis.
Exam pearl
Remember the malignancy-risk ladder: category 3 ≤2%; 4A >2–10%; 4B >10–50%; 4C >50–<95%; and category 5 ≥95%.
Viva questions
- What is the purpose of the BI-RADS assessment categories?
- They provide a standardised final breast imaging assessment linked to malignancy likelihood and an appropriate management recommendation.
- Enumerate the BI-RADS final assessment categories.
- Category 0 is incomplete; 1 negative; 2 benign; 3 probably benign; 4 suspicious; 5 highly suggestive of malignancy; and 6 known biopsy-proven malignancy.
- What does BI-RADS category 0 mean?
- The assessment is incomplete because additional imaging evaluation and/or comparison with prior examinations is required before assigning a final category.
- What is the malignancy likelihood and management of BI-RADS category 3?
- The likelihood of malignancy is greater than 0% but no more than 2%. Short-interval imaging follow-up is recommended after a complete diagnostic evaluation.
- How is BI-RADS category 4 subdivided?
- Category 4A represents greater than 2% to 10% risk, 4B greater than 10% to 50%, and 4C greater than 50% but less than 95%. Tissue diagnosis should be considered for all three.
- What distinguishes BI-RADS category 5 from category 4C?
- Category 5 has at least a 95% likelihood of malignancy and imaging features highly suggestive of cancer, whereas category 4C remains below 95% despite high suspicion.
- What is the essential requirement for assigning BI-RADS category 6?
- The malignancy must already have been confirmed histologically, and the imaging must be performed before definitive treatment.
- What is a common misuse of BI-RADS category 3?
- Using it for an incompletely evaluated or indeterminate finding. Category 3 is restricted to appropriately characterised probably benign findings with a malignancy likelihood of no more than 2%.