BI-RADS

BI-RADS (Breast Imaging Reporting and Data System) is a standardized quality assurance tool and lexicon used by radiologists to interpret and report mammography, ultrasound, and MRI findings related to the breast. Developed and maintained by the American College of Radiology (ACR), its primary purpose is to standardize breast imaging reports, reduce confusion and variability in interpretation, facilitate communication between radiologists and referring physicians, and aid in patient management. It also serves as a framework for data collection and research.

The system assigns a category score from 0 to 6 to describe the findings and the level of suspicion for malignancy, along with a recommendation for follow-up or action. Each category has specific implications for patient care:

• Category 0: Incomplete.

  • Meaning: Additional imaging (e.g., spot compression, magnification views, ultrasound) or prior mammograms are needed for a complete assessment. The radiologist has not reached a conclusion.
  • Action: Requires further evaluation.

• Category 1: Negative.

  • Meaning: The breasts are symmetrical, and no masses, architectural distortion, or suspicious calcifications are present. This is a normal study.
  • Action: Routine annual screening.

• Category 2: Benign.

  • Meaning: Benign findings are identified (e.g., clearly benign calcifications, fibroadenomas, intramammary lymph nodes), but there is no evidence of malignancy. The findings are not suspicious.
  • Action: Routine annual screening.

• Category 3: Probably Benign.

  • Meaning: A finding has a high probability (typically >98%) of being benign, but it is not entirely certain. Short interval follow-up is recommended to establish stability.
  • Action: Short interval follow-up (e.g., 6 months).

• Category 4: Suspicious Abnormality.

  • Meaning: The finding does not have the classic appearance of cancer but has a definite probability of being malignant (cancer risk generally 2-95%). This category is further subdivided into:
    • 4A (Low suspicion for malignancy): Cancer risk >2% to ≤10%.
    • 4B (Moderate suspicion for malignancy): Cancer risk >10% to ≤50%.
    • 4C (High suspicion for malignancy): Cancer risk >50% to ≤95%.
  • Action: Biopsy should be considered.

• Category 5: Highly Suggestive of Malignancy.

  • Meaning: The finding has a very high probability (typically >95%) of being malignant, with characteristic imaging features of cancer.
  • Action: Appropriate action should be taken (e.g., biopsy and definitive treatment).

• Category 6: Known Biopsy-Proven Malignancy.

  • Meaning: Malignancy has been proven by biopsy prior to the imaging study. This category is used for monitoring the response to treatment or for presurgical localization.
  • Action: Surgical excision or medical management as appropriate.

BI-RADS is regularly updated by the ACR to incorporate new imaging techniques and improved understanding of breast disease. Its widespread adoption has significantly improved the quality and consistency of breast cancer screening and diagnosis globally.