Breast imaging produces complex visual data that requires translation into a clear assessment for patients and providers. This need for consistent communication led to the development of a standardized reporting tool used globally. The system allows radiologists to communicate findings with a single numerical score, indicating the degree of suspicion and guiding the next steps in patient care. This approach ensures every patient receives a predictable and appropriate recommendation.
Standardizing Breast Imaging Reports
The standardized system used across different imaging modalities is the Breast Imaging Reporting and Data System, widely known by its acronym, BI-RADS. This tool was created by the American College of Radiology (ACR) to eliminate confusion and establish a common language among medical professionals. Before BI-RADS, a radiologist’s description of a finding might have been interpreted differently by another doctor, potentially delaying proper follow-up.
The system assigns a score ranging from 0 to 6 to the findings in a breast imaging report, providing a uniform scale of suspicion for malignancy. This classification is used for mammography, breast ultrasound, and magnetic resonance imaging (MRI). The BI-RADS score helps the healthcare team track a patient’s results over time and determines whether additional testing is required for a definitive diagnosis.
Decoding the Bi-RADS Scores
The BI-RADS classification system functions as a risk assessment tool, with each score corresponding to a specific probability of the finding being cancerous. A score of 0, designated as Incomplete, indicates that the radiologist requires additional imaging to make a final assessment, often involving specialized mammogram views or an ultrasound. A score of 1, or Negative, signifies that the breast tissue appears completely normal with no masses, distortions, or suspicious calcifications, and the patient should continue with routine annual screening.
A score of 2 is classified as a Benign Finding, meaning the radiologist has identified a non-cancerous abnormality, such as a simple cyst or benign calcifications. No further action beyond routine screening is necessary for this category. Category 3, Probably Benign, is assigned to a finding that has a very low likelihood of malignancy, specifically less than 2%. This category is reserved for lesions that exhibit classic benign characteristics.
A finding classified as Category 4, Suspicious Abnormality, necessitates a tissue sample, or biopsy, for a definitive diagnosis. The probability of cancer in this category is wide, ranging from greater than 2% to less than 95%. Category 4 is subdivided to guide the need for intervention.
Category 4 Subdivisions
Subcategory 4A indicates a low likelihood of cancer (2% to 10%).
Subcategory 4B suggests a moderate concern (10% to 50%).
Subcategory 4C carries a high probability of malignancy (50% to 95%).
A score of Category 5, Highly Suggestive of Malignancy, is assigned to findings that have the classic features of breast cancer, with a probability of being cancerous at 95% or greater. Finally, a score of Category 6, Known Malignancy, is used only after a biopsy has already confirmed the presence of cancer. This final category is utilized to monitor the size and appearance of a known tumor while the patient is undergoing treatment, such as chemotherapy or radiation.
Management and Follow-Up Recommendations
Each BI-RADS score is directly linked to a specific set of recommended actions. Patients with scores 1 and 2 are advised to continue with standard annual mammography screening. These results confirm the absence of malignancy or the presence of a known, non-threatening finding, and require no immediate intervention.
For a score of 3, the recommended action is short-interval follow-up imaging, typically a repeat unilateral mammogram or ultrasound in six months. This watchful waiting approach is used to confirm that the probably benign finding remains stable over a period of 1 to 2 years, rather than subjecting the patient to an immediate, unnecessary biopsy. If the finding resolves or remains unchanged during this period, the patient can then return to their routine annual screening schedule. However, a biopsy may be considered immediately for patients who experience high levels of anxiety or who have a strong family history that increases their overall risk.
When a score of 4 or 5 is assigned, a tissue biopsy is the necessary next step to determine the exact nature of the abnormality. This procedure, often a core needle biopsy, is performed to obtain a small sample of the suspicious tissue for microscopic examination by a pathologist. If the biopsy confirms a cancer diagnosis, which is highly likely with a Category 5 result, the patient will then begin the process of treatment planning.
A score of 6 means the patient has a confirmed cancer diagnosis, and the primary action shifts entirely to treatment, such as surgery, chemotherapy, or radiation therapy. Open and thorough communication between the patient and their physician is important to clarify the findings and the rationale for the recommended plan. For scores 4 and higher, the final course of action often involves a multidisciplinary team, including the radiologist, a surgeon, and an oncologist, who collaborate to determine the optimal strategy for care.