The Breast Imaging Reporting and Database System, or BI-RADS®, was created by he American College of Radiology (ACR) as a uniform method for radiologists to classify mammogram findings, as well as an assessment structure and a classification system for mammography and ultrasound of the breast.
BI-RADS® encompass seven standardized categories, or levels. Each category has an associated follow-up plan to help radiologists and other physicians manage a patient’s care. Both screening and diagnostic mammogram results are coded according to the American College of Radiology system BI-RAD® system.
BI-RADS® Assessment Categories
a. Mammographic Assessment Is Incomplete
Category 0 / Need Additional Imaging Evaluation and/or Prior Mammograms for Comparison
Finding for which additional imaging evaluation is needed. This is almost always used in a screening situation. Under certain circumstances this category may be used after a full mammographic workup. A recommendation for additional imaging evaluation may include, but is not limited to the use of spot compression, magnification, special mammographic views and ultrasound. Whenever possible, if the study is not negative and does not contain a typically benign finding, the current examination should be compared to previous studies. The radiologist should use judgment on how vigorously to attempt obtaining previous studies.
Category 0 should only be used for old film comparison when such comparison is required to make a final assessment.
b. Mammographic Assessment Is Complete
Category 1 / Negative
There is nothing to comment on. The breasts are symmetric and no masses, architectural distortion or suspicious calcifications are present.
Category 2 / Benign Finding(s)
Like Category 1, this is a “normal” assessment, but here, the interpreter chooses to describe a benign finding in the mammography report. Involuting, calcified fibroadenomas, multiple secretory calcifications, fat-containing lesions such as oil cysts, lipomas, galactoceles and mixed-density hamartomas all have characteristically benign appearances, and may be labeled with confidence. The interpreter may also choose to describe intramammary lymph nodes, vascular calcifications, implants or architectural distortion clearly related to prior surgery while still concluding that there is no mammographic evidence of malignancy. Note that both Category 1 and Category 2 assessments indicate that there is no mammographic evidence of malignancy. The difference is that Category 2 should be used when describing one or more specific benign mammographic findings in the report, whereas Category 1 should be used when no such findings are described.
Category 3 / Probably Benign Finding — Initial Short-Interval Follow-Up Suggested
A finding placed in this category should have less than a 2% risk of malignancy. It is not expected to change over the follow-up interval, but the radiologist would prefer to establish its stability. There are several prospective clinical studies demonstrating the safety and efficacy of initial short-term follow-up for specific mammographic findings (1-5). Three specific findings are described as being probably benign (the noncalcified circumscribed solid mass, the focal asymmetry and the cluster of round [punctate] calcifications; the latter is anecdotally considered by some radiologists to be an absolutely benign feature). All the published studies emphasize the need to conduct a complete diagnostic imaging evaluation before making a probably benign (Category 3) assessment; hence it is inadvisable to render such an assessment when interpreting a screening examination. Also, all the published studies exclude palpable lesions, so the use of a probably benign assessment for a palpable lesion is not supported by scientific data. Finally, evidence from all the published studies indicates the need for biopsy rather than continued follow-up when most probably benign findings increase in size or extent. While the vast majority of findings in this category will be managed with an initial short-term follow-up (6 months) examination followed by additional examinations until longer-term (2 years or longer) stability is demonstrated, there may be occasions where biopsy is done (patient wishes or clinical concerns).
Category 4 / Suspicious Abnormality — Biopsy Should Be Considered
This category is reserved for findings that do not have the classic appearance of malignancy but have a wide range of probability of malignancy that is greater than those in Category 3. Thus, most recommendations of breast interventional procedures will be placed within this category.
Category 5 / Highly Suggestive of Malignancy — Appropriate Action Should Be Taken
These lesions have a high probability (≥95%) of being cancer. This category contains lesions for which one-stage surgical treatment could be considered without preliminary biopsy. However, current oncologic management may require percutaneous tissue sampling as, for example, when sentinel node imaging is included in surgical treatment or when neoadjuvant chemotherapy is administered at the outset.
The MQSA regulations require a facility to provide mammography reports to referring healthcare providers and lay summaries to its patients within 30 days of the date of the exam. The regulations also require that if the final assessment is “Suspicious” or “Highly Suggestive of Malignancy”, the facility should provide the mammography report and lay summary as soon as possible (ASAP). The FDA guidance interprets ASAP as within 3 days for the report to the healthcare provider and within 5 days for the lay letter to the patient.
Category 6 / Known Biopsy — Proven Malignancy — Appropriate Action Should Be Taken
This category is reserved for lesions identified on imaging study with biopsy proof of malignancy prior to definitive therapy.
Cytopathologists record their Pap test findings using the 2001 Bethesda System, which specifies specimen adequacy and is a descriptive diagnostic system that provides specific categories for abnormal findings, which in turn promote specificity in treatments.
The Bethesda System was updated in 1991 and again in 2001. The 2001 Bethesda System has three general reporting elements: specimen adequacy, general categorization, and interpretation/result.
There are 7 BCC codes within the Bethesda system.
- Negative for intraepithelial lesion or malignancy.
- Atypical squamous cells of undetermined signficance (ASC-US).
- Low grade squamous intraepithelial lesion (LSIL). This includes HPV and mild dysplasia.
- Atypical squamous cells — cannot exclude high grade SIL (ASC-H).
- High grade squamous intraepithelial lesion (HSIL) encompassing moderate dysplasia (CIN2), as well as CIN 3, which includes severe dysplasia carcinoma in situ (CIS).
- Squamous cell carcinoma
- Abnormal glandular cells including atypical glandular cells of undetermined significance (AGUS): endocervical adenocarcinoma; endocervical adenocarcinoma in situ; endometrial adenocarcinoma; extrauterine adenocarcinoma; adenocarcinoma, NOS
- Unsatisfactory Cytology
- Cytology Negative for Intraepithelial Lesion or Malignancy (NILM) but EndoCervix (EC)/Transformation Zone (TZ) Absent/Insufficient
- Normal Cytology/HPV Positive
- ASC-US or LSIL: Age 21-24
- LSIL Pregnant Women
- ASC-H and HSIL: Age 21-24
- AGC Subsequent Management