BI-RADS The American College of Radiology Breast Imaging Reporting and Data System
BI-RADS
The American College of Radiology Breast Imaging Reporting and Data System
This overview relates to the BI-RADS system for Mammography, but it applies, in general, to BI-RADS for Ultrasound and Magnetic Resonance Imaging of the breast. I have, recently, been asked specific questions about BI-RADS so I thought this overview might be helpful.
A BRIEF HISTORY OF BI-RADS
Mammography screening began, haphazardly, in the U.S. in the1980’s. There has never been a government guided, centrally coordinated, overall organization to oversee screening in the U.S. although the Food and Drug Administration (FDA) does monitor quality issues.
In the early to mid-1980’s approximately 20% of women had their first screening mammogram and this increased steadily until it plateaued in the late 1990’s when approximately 70% of women ages 40 and over had had at least one mammogram ¹.
As more and more women participated in screening, the poor quality of the mammography reporting became evident. Radiologists were dictating reports that were “stream of consciousness” and often left our clinical colleagues uncertain as to what the study showed and what should be done for the patient. This became apparent in a white paper that was highly critical of the low quality of mammography reporting ².
In the late 1980’s the American College of Radiology assembled a group of radiologists who were expert in Breast Imaging and also invited a leading breast surgeon and others to address the reporting issues. Dr. Carl D’Orsi and I were co-chairmen. I had developed a reporting system for my Breast Imaging Division at the Massachusetts General Hospital ³ and Dr. D’Orsi had worked with a company called Bolt, Beranek, and Newman in developing a vocabulary for mammography reporting. The evolution of BI-RADS is explained in an overview by Burnside et al ⁴.
The goal of BI-RADS was to develop a clearly defined dictionary of terms for describing findings on a mammogram. This is known as the “Lexicon” and was based on the work done by Dr. D’Orsi. The categories and organization of BI-RADS were based on my reporting system. BI-RADS explains how a report should be organized, and defines each type of finding, its significance, and how it should be categorized ranging from:
BI-RADS 0:
Although there are times when a lesion can be definitively determined to be malignant on a screening examination, it is best to have the patient who has any findings that raise suspicion to be categorized as “BI-RADS 0” which indicates there are findings that are uncertain and the patient should return for more definitive diagnostic evaluation.
BI-RADS 1:
is used when the mammogram is negative with nothing to report.
BI-RADS 2:
is used when there is a clearly benign finding that the radiologist wants to describe so that anyone else looking at the mammogram will not be confused.
BI-RADS 3:
is used for findings on the mammogram that have a low probability of being cancer (less than 2% likelihood), but that the radiologist wants to follow at a shorter interval based on the annual interval that is recommended for all women. The shorter interval is six months and BI-RADS suggests that the finding be followed up at 6 months, 12 months and then annually for a total of 3 years from the study that first identified the finding. Our experience at the Massachusetts General Hospital led us to follow-up these women every 6 months for a total of 2 years.
BI-RADS 4 ：
has been divided into 4a, 4b, and 4c. Biopsy (tissue diagnosis) is recommended for all 3 subcategories, but some radiologists wanted to grade these findings within BI-RADS 4.
BI-RADS 5 ：
was originally created for rural locations where getting patients to return foe additional evaluation was difficult. The appearance of the lesion is so characteristic of a breast cancer that it was not unreasonable to do an immediate biopsy.
BI-RADS 6 ：
is used when there is a known breast cancer (pathologically proven) that is still evident on the mammogram, but the mammogram is being done to evaluate other areas of the breast.
The primary reason for BI-RADS was to reduce any confusion about the interpretation of the mammogram and to be certain that every report had a clear, action defined, conclusion and, if needed, clear levels of concern and clear guidance for the next test if needed.
A secondary, but very important goal for BI-RADS was to allow radiologists to collect data to track their own reports and those in their screening program to determine what actually happened to each patient. This was ultimately codified by the “Audit” that was described by Dr. Edward Sickles ⁵ which allowed us to track our patients and learn from the outcomes of each examination and improve future mammographic analyses. By tracking our results, we were able to understand the results of our efforts and to improve our mammographic interpretations.
ORGANIZATION
Each study should be categorized as “Screening” or “Diagnostic”.
“Screening” involves women who have no signs or symptoms of breast cancer. They have no clinically evident findings and are being routinely, and periodically having their mammograms with the goal of discovering breast cancer earlier than when it becomes clinically evident. The most lives are saved by annual screening starting at the age of 40 ⁶
Women having “Diagnostic” evaluation have either something evident on clinical examination or breast symptoms such as focal pain, a “lump”, thickening, nipple changes or discharge, or are women who have had something found on their screening mammogram and are returning to have the finding evaluated.
OUTLINE OF THE REPORT
The reason for the study should be provided at the start of the report. I always include the menopausal status of the individual and like to include the age of the patient.
Eg: “This is a 57 year old, post-menopausal female having a screening study.”
Given the importance of breast density as potentially obscuring a lesion (with some slight increase in risk for older women with the densest pattern) the tissue pattern should be reported.
“The breast tissues are heterogeneously dense” and then I indicate that sensitivity is reduced by stating “this, somewhat, lowers the sensitivity of mammography”.
If there is nothing to report, then our report provides a simple summary of the absence of the major malignant criteria:“No mases or clustered microcalcifications are evident.”
Since there are cancers that can be hidden by dense breast tissue, the clinician should always be told that, even if the mammogram is negative, “Any decision for further evaluation should be based on the clinical evaluation”.
This last statement is also important if the patient has had a diagnostic evaluation for a clinically evident finding that is not defined by the mammogram so that the clinician is not dissuaded from further evaluation of the finding.
Then:“CONCLUSION: There is no mammographic evidence of malignancy.”I state “mammographic” since if there are clinically evident findings the referring physician should act on those.
At the bottom of the report is:“BI-RADS 1”
OTHER FINAL ASSESSMENTS
If there is a benign finding on the mammogram that might confuse someone, then I will describe it. For example:“There are numerous linear calcifications that project over both breasts that are typical of benign “secretory” deposits. There is no mammographic evidence of malignancy.”
“CONCLUSION: Benign calcifications with no mammographic evidence of malignancy.”
“BI-RADS 2”
If there is a suspicious finding, then the report might read:“There is a 1 cm, spiculated mass distorting the architecture in the upper outer left breast. No other masses or clustered microcalcifications are identified. Additional evaluation with mammography and ultrasound is recommended.”
“CONCLUSION: Suspicious lesion left breast, additional evaluation is recommended.
BI-RADS 0
When the patient returns for “Diagnostic evaluation”, then the report might read:“There is a 1 cm. in diameter irregular shaped mass with spiculated margins in the upper outer left breast posterior at 1:00. Ultrasound was performed and showed that the lesion is solid with posterior acoustic shadowing. This should be viewed with a high degree of suspicion and likely represents a malignant lesion. Ultrasound guided core needle biopsy could be performed.
CONCLUSION:Very suspicious mass left breast, biopsy is recommended.
BI-RADS 4
MULTIPLE FINDINGS
I have been asked how to manage multiple findings within BI-RADS. In the body of the report, each finding should be described and categorized.
There are multiple findings in the right breast:
1. There is an ill-defined, 8 mm. in diameter mass in the center of the right breast. Additional imaging is recommended.
2. There is a second, ill-defined 12 mm in diameter density in the 3:00 mid portion of the right breast. Additional imaging of this lesion is recommended.
3. There are numerous lucent centered, benign calcifications scattered throughout both breasts.
CONCLUSION: There are two suspicious lesions in right breast. Additional imaging is recommended.
BI-RADS 4
Again, the main goal of BI-RADS is to provide a clear and accurate analysis of the imaging study. A detailed description in the body of the report should be provided using descriptive terms that are clear and concise. The BI-RADS Lexicon of terms should be used for most descriptions so that there is no confusion.
The CONCLUSION should be concise and accurate with a clear recommendation if further evaluation is needed.
In the U.S. we put the BI-RADS code at the bottom of the report. If there are multiple findings we chose the one that defines the most consequential finding in the analysis. This doesn’t mean that there is only a single finding but indicates whether or not there is an indication that requires additional attention.
REFERENCES
1. Breen N, A Cronin K, Meissner HI, Taplin SH, Tangka FK, Tiro JA, McNeel TS. Reported drop in mammography : is this cause for concern? Cancer. 2007 Jun 15;109(12):2405-9.
2. Scott, W. Establishing mammographic criteria for recommending surgical biopsy. Chicago, Ill: American Medical Association; 1989.
3. Kopans DB. Breast Imaging. J.B.Lippincott Co. Philadelphia, Pa. 1989. p. 351
4. Burnside ES, Sickles EA, Bassett LW, Rubin DL, Lee H, Ikeda M, Mendelson EB, Wilcox P, Butler F, D’Orsi CJ. The ACR BI-RADS® Experience: Learning From History. J Am Coll Radiol Volume 6, Issue 12, December 2009, Pages 851-860.
5. Sickles EA, Ominsky SH, Sollitto RA, Galvin HB, Monticciolo DL. Medical audit of a rapid-throughput mammography screening practice: methodology and results of 27,114 examinations. Radiology. 1990 May;175(2):323-7.
6. Mandelblatt JS, Cronin KA, Bailey S, Berry DA, de Koning HJ, Draisma G, Huang H, Lee SJ, Munsell M, Plevritis SK, Ravdin P, Schechter CB, Sigal B, Stoto MA, Stout NK, van Ravesteyn NT, Venier J, Zelen M, Feuer EJ; Breast Cancer Working Group of the Cancer Intervention and Surveillance Modeling Network. Effects of mammography screening under different screening schedules: model estimates of potential benefits and harms. Ann Intern Med. 2009 Nov 17;151(10):738-47.
