BI-RADS Terminology for Mammography Reports: What Residents Need to Know

1. BI-RADS Terminology for Mammography Reports: What Residents Need to Know Karina Pesce, MD, PhD María B. Orruma, MD Carolina Hadad, MD Yesenia Bermúdez Cano, MD Roberto Secco, MD Andrea Cernadas, MD

2. Authors’ Affiliation: Department of Breast Radiology Hospital Italiano de Buenos Aires Pres. Tte. Gral. Juan Domingo Perón 4190 C1199 ABB, Buenos Aires, Argentina Corresponding Author: Karina Pesce, MD, PhD e-mail: drakarina.pesce@gmail.com Presented as an education exhibit (BR 176-ED-X) at the 2017 RSNA Annual Meeting. All authors have disclosed no relevant relationships.

3. Introduction • The structure of the Breast Imaging Reporting and Data System (BI-RADS) lexicon lends itself to the consistent and rational evaluation of mammographic findings and facilitates resident and breast imaging fellowship training. • Both the American College of Radiologists (ACR) and the Society of Breast Imaging recommend that breast imaging education within residency and fellowship programs should require the use of BI-RADS terminology, assessment categories, and management recommendations.1 • In this presentation, we present the updated lexicon for mammography from the BI-RADS fifth edition,2using examples of original cases to illustrate the BI-RADS terminology used to facilitate the education of resident radiologists.

4. Describe breast lesions by using the correct BI-RADS descriptors. • Determine the appropriate BI-RADS category at mammography. • Define the indications for using a BI-RADS category 3 at mammography. • Develop a skillful and practical approach to performing and interpreting mammograms using the BI-RADS lexicon.

5. 1 2 3 4 The illustrative BI-RADS fifth edition2 is a product of years of collaboration among subsection heads, committees, and the ACR, and most importantly, input from users of the system.

6. Mammography Report Structure • Indication for examination • Succinct description of the overall breast composition • Clear description of any important findings with comparison to previous examinations • Assessment • Management 1 • Perform mammography • Recall a screening-detected finding and evaluate a clinical finding • Specify the finding and its location • Follow-up as either a probably benign lesion or cancer, treated with breast conservation

7. 2Descriptors of Breast Density (a-d) Mediolateral oblique (MLO) mammograms show the various types of breast tissue density according to the ACR. The BI-RADS written descriptors of breast density should be used in the radiologic report. Letters or numbers should not be used. • Scattered areas of fibroglandular densities a c d b • Extremely dense tissue • Almost • entirely fatty tissue • Heterogeneously • dense tissue

8. 3Findings Described in the BI-RADS Lexicon • Provide a clear description of any important findings. • It is assumed that most important findings are (a) of concern at screening, (b) inherently suspicious, (c) new, or (d) interpreted to be larger and/or more extensive when compared to the findings depicted at previous examinations. Asymmetries * Microcalcifications • Architectural distortion Mass

9. Masses Depicted at Mammography: Morphology Higherprobabilityof a benign lesion A mass is defined as a three-dimensional occupying lesion that is seen on two different mammographic projections. • What do residents need to know when describing a mass depicted at mammography? • Remember these mnemonics: • Shape: ROI • Margin: COMIS Higherprobability of malignancy

10. Masses Depicted at Mammography: Density, Calcifications, Associated Features, and Location Mass Higherprobabilityofbenign Higherprobabilityof a benign lesion • Associated features to describe include: • Architectural distortion and edema • Duct changes • Skin thickening • Skin retraction • When describing the location of the mass, include its: • Laterality • Quadrant and clock-face description • Depth • Distance from the nipple Higherprobability of malignancy

11. Typically Benign Microcalcifications • Popcorn-Like • Vascular Dystrophic • Skin c b Round Popcorn-like d e a Vascular • Round Mammograms obtained from different patients show typically benign microcalifications (arrow), including skin (a), dystrophic (b), round (c), vascular (d), and popcorn-like (e). • Skin: Typically lucent-centered and pathognomonic in appearance • Dystrophic: Irregular shape, usually > 1 mm in diameter, often with lucent centers • Round: May be considered benign when diffuse and small (< 1 mm) and are frequently formed in the acini of lobules. When smaller than 0.5 mm, the term punctate should be used to describe these findings. • Vascular: Parallel tracks or linear tubular calcifications that are clearly associated with blood vessels • Popcorn-like: Classic large calcifications (> 2–3 mm at the greatest diameter); produced by an involuting fibroadenoma • Describing distribution may not be appropriate for typically benign calcifications. Round Routine Mammography Screening Management • Rim Continued on next slide

12. Typically Benign Microcalcifications: Continued Rim Suture Milk-of-calcium • Large rodlike • Round f h g i Mammograms obtained from different patients show more typically benign microcalifications (arrow), including large rodlike (f), milk-of-calcium (g), suture (h), and rim (i). • Large rodlike: Associated with ductal ectasia; may form solid or discontinuous smooth linear rods, most of which are 0.5 mm or larger in diameter • Milk-of-calcium: Manifestation of sedimented calcifications in macro- or microcysts, usually but not always grouped. On craniocaudal (CC) views, they are often less evident and appear as round smudgy deposits, while occasionally on MLO views and especially on 90° lateral (lateromedial/mediolateral [ML]) views they are more clearly defined and are often semilunar, crescent shaped, curvilinear (concave up), or linear, defining the dependent portion of the cysts. • Suture: Calcium deposited on suture material • Rim: Thin benign calcifications that appear as calcium deposited on the surface of a sphere Round Management Routine Mammography Screening • Rim

13. Microcalcifications: Distribution The distribution of microcalcifications can indicate the positive predictive value (PPV) for malignancy in BI-RADS. The illustration depicts an MLO view of the breast that details the PPV with the corresponding type of distribution, along with corresponding insets of cropped mammograms. • Grouped • PPV = 31% • 5 or more microcalcifications within 1 cm3, maximum 2 cm • Segmental • PPV = 62% • Calcium deposits in the ducts and branches of a segment or lobe Diffuse PPV 0% • Regional • PPV = 26% • Scattered in a larger volume (> 2 cc) of breast tissue and not in the expected ductal distribution • Linear • PPV 60% • Arrayed in a line is a finding suggestive of deposition along the ducts

14. Suspicious Microcalcifications Coarse heterogeneous Amorphous b a • Magnified areas of interest from mammograms show amorphous (arrows in a) and coarse heterogenous (arrow in b) calcifications. The patient depicted in a underwent a stereotactic core biopsy, the results of which confirmed atypical apocrine adenosis. The patient depicted in b underwent a stereotactic core biopsy, the results of which confirmed a high-grade intraductal carcinoma. • Morphology, distribution, associated features, and location of suspicious microcalcifications should be included in the radiologic report. • Amorphous: PPV: 21% BI-RADS category 4B; so small and/or hazy in appearance that a more specific particle shape cannot be determined • Coarse heterogeneous: PPV: 13% BI-RADS category 4B; irregular conspicuous calcifications that are generally 0.5 mm–1 mm in diameter and tend to coalesce but are smaller than dystrophic calcifications Management Tissue diagnosis

15. Suspicious Microcalcifications: Continued Fine pleomorphic Fine linear or fine-linear branching c d • Mammograms show fine plemorphic (arrow in c) and fine linear or fine-linear branching (arrow in d) calcifications. Both patients underwent stereotactic core biopsies, and the results of each confirmed high-grade intraductal carcinoma. • Morphology, distribution, associated features, and location of suspicious microcalcifications should be included in the radiologic report. • Fine pleomorphic: PPV = 29%, BI-RADS category 4C; usually more conspicuous than amorphous forms and have discrete shapes. These irregular calcifications are distinguished from fine linear and fine linear branching forms by the absence of fine-linear particles. Fine pleomorphic calcifications vary in size and shape and are usually less than 0.5 mm in diameter. • Fine linear or fine-linear branching: PPV = 70%, BI-RADS category 4C. Thin linear irregular calcifications that may be discontinuous and less than 0.5 mm in caliber. Occasionally, branching forms may be seen. Their appearance suggests filling of the lumen of a duct or ducts involved irregularly by breast cancer. Management Tissue diagnosis

16. Architectural Distortion What is the next step? Diagnostic evaluation and obtaining additional mammographic views at three-dimensional (3D) mammography and breast US. MLO mammogram shows architectural distortion (arrow). In the absence of history of trauma or surgery, architectural disortion is suspicious for malignancy or radial scar.

17. Asymmetry Clinical Pearl Diagnosing asymmetry involves a careful analysis and the comparison with at least one (often more) previous examination. It should include a diagnostic evaluation with additional mammographic views and breast US images, and 3D mammography may also be performed for the evaluation. a b a b (a) MLO mammogram shows an area of asymmetry (arrow). (b) CC mammogram does not show the asymmetry. Asymmetry: An area of dense fibroglandular tissue that is visible on only one mammographic projection. Most of these findings represent summation artifacts and superimposition of normal breast structures. A one-view findingthatlacksconvex borders that may ormaynotcontaininterspersed fat occupies lessthanonequadrantofthe breast. (a, b) Mammograms show a focal asymmetry (arrow). Focal asymmetry is evaluated relative to the corresponding location in the contralateral breast and represents a relatively small amount of dense fibroglandular tissue over a confined portion of the breast (less than one quadrant). A two-view finding that lacks convex borders (may or may not contain interspersed fat) occupies less than one quadrant of the breast, similar in appearance to that depicted on CC and MLO views.

18. Asymmetry: Continued b a b a (a, b)Bilateral MLO mammograms show a global asymmetry (arrow). Global asymmetry: Global asymmetry is evaluated relative to the corresponding area in the contralateral breast and represents a large amount of dense fibroglandular tissue over a substantial portion of the breast (at least one quadrant). There is no mass, architectural distortion, or associated suspicious calcifications. Global asymmetry usually represents a normal variant. MLO mammograms obtained in 2017 (a) and 2018 (b) show the development of an asymmetry (arrow). Developing asymmetry: This is a focal asymmetry that is new, larger, and more conspicuous than that depicted on a previous examination. Approximately 15% of developing asymmetries are found to be malignant, so these cases warrant further imaging evaluation and biopsy unless found to be characteristically benign at further workup.

19. Solitarydilatedduct Skin lesion a b Mammogram shows a skin lesion (arrow). This finding may be described in the mammography report or annotated on the mammographic image when it projects over the breast (especially on two different projections) and may be mistaken for an intramammary lesion. A raised skin lesion that is large enough to be seen at mammography should be marked by the technologist with a radiopaque device designated for use as a marker for a skin lesion. Dots = marked raised skin lesion. Mammograms show a solitary dilated duct (arrow). Solitary dilated duct is a rare mammographic finding, and it can be associated with noncalcified ductal carcinoma in situ (DCIS).3 Solitary dilated duct appears to have a greater than 2% likelihood of malignancy, sufficiently high enough to suggest that a suspicious (BI-RADS category 4A) assessment may be appropriate. 3 Chang CB, Lvoff NM, Leung JW, Brenner RJ, Joe BN, Tso HH, Sickles EA.Solitary dilated duct identified at mammography: outcomes analysis. AJR Am J Roentgenol. 2010;194(2):378-382. Continued on next slide

20. Skin lesion Intramammary Lymph Node • Mammogram shows a normal intrammary lymph node (arrow). • A normal intramammary lymph node is a mass less than 1 cm in diameter that is well circumscribed and slightly lobulated. In addition, in most instances, a radiolucent cleft (which represents fat in the hilum of the node) is depicted. The typical location of these nodes is the upper outer quadrant of the breast.

21. Determining Lesion Location in the Breast • A complete set of lesion location descriptors should include: • Designationof the finding in the right orleftbreast • Quadrant and clock-face notation (preferablyboth) • Depth (anterior, middle, or posterior third) • Distancefromnipple RIGHT 8’clock Lateral Superior posterior anterior middle Distance from the nipple Medial Inferior CC view  MLO view CC view  MLO view Illustration shows the right breast. Illustration shows the left breast.

22. Assessing Location Compare recent mammography examinations with previous examinations, if deemed appropriate by the interpreting physician

23. Assessment and Patient Management A significant change in the fifth edition of BI-RADS that is relevant to all breast care providers is the separation of the BI-RADS assessment from patient management. 4 The separation was implemented to provide more flexibility for several specific clinical cases for which a seemingly discordant management recommendation might be appropriate for a given assessment. 5

24. 4 BI-RADS Assessment Categories BI-RADS 0: Needs additionalimage evaluation and/or prior mammograms for comparison BI-RADS 1: Negative (0% likelihood of malignancy) BI-RADS 2: Benign (0% likelihood of malignancy) BI-RADS 3: Probably benign (0 % to ≤ 2% likelihood of malignancy) • BI-RADS 4: Suspiciousabnormality(likelihoodof malignancy: 4A = 2%–10%, 4B =10%–50%, and 4C = 50%–95%) BI-RADS 5: Highly suggestive of malignancy (≥ 95% likelihood of malignancy) BI-RADS 6: Known biopsy-provenmalignancy

25. Management: BI-RADS Category 1 • Management a b Bilateral MLO (a) and CC (b) mammograms show a normal examination. There are no findings to comment on. Routine mammography screening

26. BI-RADS Category 1 • Case 1: CC (a) and MLO (b) mammograms show dense breast tissue. • In this case, assign the screening mammography a BI-RADS category 1. • Negative Mammogram • With or without palpable breast nodule Assign a BI-RADS 1 category if there are no abnormal imaging findings in a patient with a palpable abnormality, (possibly a palpable cancer), but add a note in the report recommending surgical consultation or tissue diagnosis if clinically indicated. a b

27. Management • BI-RADS Category 2: Benign Assessment Spectrum of Benign Findings Routine mammography screening

28. BI-RADS Category 3: Probably Benign4 These findings are generally depicted on baseline examinations. IMPORTANT A BI-RADS 3 should not be assigned at screening mammography. It should be assigned after a diagnostic workup has been completed. • Focal asymmetry (arrows) A focal asymmetry should be nonpalpable and should not have have a sonographic correlate. Continued on next slide

29. BI-RADS Category 3: Probably Benign4 The fifth edition of BI-RADS is more flexible than previous editions as it allows for a BI-RADS category 3 to be assigned (even if the lesion is not part of the three findings accepted as BI-RADS category 3) if the radiologist has had personal experience to support this assignment. Examples include: • Developing calcifications (arrow in a) that seem to be most likely vascular, but not definitely “I don’t know.” “It is strange.” “I had a similar cancer case.” “I am not sure about it.” a • Calcifications that are suggestive of early evolving fat necrosis  • Lesions (arrows in b and c) in which stability evaluation is difficult owing to technical differences between an analog image (b) and a digital image (c). The can also occur when comparing images obtained using equipment from different vendors. • IMPORTANT b c • BI-RADS 3 should not be used when a radiologist is “not sure” whether a finding is benign or suspicious. 2012 2013

30. BI-RADS Category 3: Management Follow-up Algorithm IMPORTANT • If the BI-RADS category 3 lesion disappears or becomes apparently benign before the 2-year follow-up, assign a BI-RADS 2 category. InterobserverVariability If stable, follow-up for 2 years Disagreement on the use of BI-RADS descriptors from one examination to the next may lead to an upgrade in the BI-RADS categorization without any demonstrable change between examinations. • If the lesion increases in size (> 20% diameter) during follow-up, update the category to a BI-RADS category 4 and recommend biopsy. The increase in size (> 20%) applies to masses (likely fibroadenomas).

31. BI-RADS Category 4: Suspicious for Malignancy Mammographic Examples BI-RADS 4A Solitarydilatedduct • Category 4A: • Low suspicion • for malignancy • Management BI-RADS 4B Microcalcifications: coarseheterogeneous • Category 4B: • Moderate suspicion for malignancy Tissue Diagnosis • Category 4C: • High suspicion for malignancy BI-RADS 4C Architecturaldistortion Division into BI-RADS 4A, 4B, 4C is an option.

32. BI-RADS Category 5: High Risk for Malignancy • Chance of malignancy ≥ 95% • Assigned for classic cases of malignancy • If the results of a biopsy indicate a benign lesion, recommend a repeat (usually surgical) biopsy. • Recommendation should be noted as follows: “Biopsy should be performed in the absence of clinical contraindication.” Examples: Magnified Areas of Interest on Mammograms Irregular spiculated high-density mass (arrow) with associated microcalcifications Irregular-shaped high-density mass (arrow) with skin retraction and calcifications New segmental fine-linear branching calcifications (arrow)

33. BI-RADS Category 6: Biopsy-Proven Malignancy • This category is reserved for examinations performed after the results of a biopsy indicate malignancy (eg, imaging performed after percutaneous biopsy but prior to complete surgical excision) in which there are no mammographic abnormalities other than the known cancer that might need additional evaluation. When to use it: Assign this category after monitoring response to neoadjuvant chemotherapy. BI-RADS category 6 is commonly assigned at preoperative MRI (when only the malignancy is depicted and there are no other suspicious findings). a b ML (a) and CC (b) mammograms show a right inferior internal quadrant mass, skin edema, and axillary adenopathies

34. Case 2: Unilateral Axillary Adenopathy (a) MLO mammogram shows unilateral axillary adenopathy (arrow) with no suspicious findings in the breasts. Screening mammography = BI-RADS 0. Consequently, a careful search of the ipsilateral breast images is warranted. Think: The presence of unilateral axillary adenopathy suggests occult breast carcinoma or, much less commonly, lymphoma, metastatic melanoma, ovarian cancer, or other metastatic cancers. (b) Bilateral axillary US image shows asymmetry. Bilateral US should be performed to confirm that the finding is asymmetric and/or unilateral. a BI-RADS Category 4 Why? In the absence of a known infectious or inflammatory cause, isolated unilateral axillary adenopathy is suspicious for malignancy. b

35. Case 3: Bilateral Axillary Adenopathy (a) Bilateral MLO mammograms show bilateral axillary adenopathy (arrows) with no suspicious findings in the breasts in a patient with known lymphoma. Clinical Pearl In this case, bilateral axillary adenopathy is presumed owing to the known diagnosis of lymphoma. b (b) US image shows axillary adenopathy with loss of the hilar cortical relationship. BI-RADS Category 2 Why? Because in this case, the BI-RADS assessment should be determined on the basis of the imaging findings depicted in the breasts, but the report also should indicate the presence of adenopathy and the known underlying disease. a

36. Case 4: Postsurgical Scarring Mammography is performed after an attempted complete surgical excision, and the results of a pathologic examination indicate positive resection margin. (a, b) Mammograms show postsurgical scarring. If images show only postsurgical scarring (although the results of a pathologic examination are margin positive), then BI-RADS category 2 should be assigned. An extra note stating that the pathology report suggests a residual tumor should be included in the radiology report. a b

37. Case 5: Assessment-Management Discordance ML (a) and CC (b) mammograms, magnification of the retroareolar section (c), and US image (d) show no imaging findings of malignancy in a woman with clinically suspected Paget disease. (e) Photograph shows an erythematous scaly patch with oozing and crusting in the areola, which effaces the nipple.It is important to know the clinical manifestations of Paget disease because they can be the only signs of the breast cancer. CC CC ML Paget DiseaseSymptoms Itching, eczema, erythema of the nipple and areola, nipple erosion or ulceration, scaly or flaky skin, nipple retraction, bloody discharge from the nipple, or a combination of these d e c b a BI-RADS Category 2 Why? Because in this situation, the BI-RADS assessment should be determined on the basis of the imaging findings depicted in the breasts. Continued onnextslide

38. Assessment-Management Discordance: Continued Another case that involves assessment-management discordance occurs in a patient with clinical suspicion for Paget disease but no mammographic or US findings that suggest malignancy. BI-RADS Category 1 Why? Because in this situation, the BI-RADS assessment should be determined on the basis of the imaging findings depicted in the breasts. Performing breast MRI is the appropriate follow-up option. IMPORTANT! BI-RADS category 0 should not be used for diagnostic breast imaging findings that warrant further evaluation with MRI.

39. No, because there has been no consensus on establishing the use of specific-shaped markers to represent palpable versus skin lesions. Skin Marking Isthere BI-RADS guidanceconcerningthestandardizationofbreast skin markers in the fifth edition? Skinlesion To properly educate interpreting physicians, an institution should adopt a policy requiring the consistent use of two different shapes of radiopaque markers for marking palpable and skin lesions. Nodule Palpable Scar Magnified areas of interest on mammograms demonstrate various methods of denoting skin markings.

40. Follow-up Postlumpectomy 2016 2016 a 2017 b 2017 Mammograms from 2016 (a) and 2017 (b) show an increase in architectural distortion (lines).

41. Mammography in Men Do mammography examinations performed on men require a BI-RADS final assessment and/or numeric code? • All mammography examinations regardless of the patient’s sex must have a final BI-RADS assessment category (but not a numeric code) in the mammography report. However, management recommendations may differ from those made for women because annual screening mammography is not usually appropriate for men. a b c (a–c) Mammograms obtained in a male patient show an irregular subareolar mass with spiculated margins.

42. Testing Yourself On the basis of the findings denoted by the arrow on the straight lateral (90°) magnification view from a mammogram, which BI-RADS category should be assigned? As depicted on the accompanying mammogram, in which of the following cases would a BI-RADS category 6 assignment be most appropriate? The finding denoted by the arrow in the CC mammogram of the right breast is most likely which of the following? A. Suspicious abnormality; a biopsy should be performed. B. Postprocedure mammography for marker placement. C. Recent biopsy-proven breast cancer. D. Previously treated breast cancer. A. An oil cyst. B. A calcified fibroadenoma. C. Fat necrosis. D. Milk-of-calcium calcification. A.BI-RADS 3. B.BI-RADS 4. C.BI-RADS 1. D.BI-RADS 2. B. Popcorn-like calcifications (arrow) are findings compatible with calcified fibroadenoma. D. On straight lateral (90°) magnification view, layering the calcifications (arrow) would be necessary in order to make the diagnosis of benign milk-of-calcium calcifications. C. BI-RADS category 6 is assigned to patients with a cancer diagnosis who have not yet been definitively treated.

43. Conclusion

44. Suggested Readings • D’Orsi CJ, Kopans DB. Mammography interpretation: the BI-RADS method. Am Fam Physician 1997;55(5):1548–1550, 1552. • D’Orsi CJ, Sickles EA, Mendelson EB, et al. ACR BI-RADS atlas, Breast Imaging Reporting and Data System. 5th ed. Reston, Va: American College of Radiology, 2013. • Mercado CL. BI-RADS update. Radiol Clin North Am 2014;52(3):481–487. • Michaels AY, Birdwell RL, Chung CS, Frost EP, Giess CS. Assessment and management of challenging BI-RADS category 3 mammographic lesions. RadioGraphics 2016;36(5): 1261–1272. • Rao AA, Feneis J, Lalonde C, Ojeda-Fournier H. Pictorial review of changes in the BI-RADS fifth edition. RadioGraphics 2016;36(3):623–639. • Sickles EA, Philpotts LE, Parkinson BT, et al. American College of Radiology/Society of Breast Imaging curriculum for resident and fellow education in breast imaging. J Am Coll Radiol 2006;3(11):879–884. • Tabár L, Vitak B, Chen TH, et al. Swedish two-county trial: impact of mammographic screening on breast cancer mortality during 3 decades. Radiology 2011;260(3):658–663.

45. References • Sickles EA, Philpotts LE, Parkinson BT, et al. American College of Radiology/Society of Breast Imaging curriculum for resident and fellow education in breast imaging. J Am Coll Radiol 2006;3(11):879–884. • D’Orsi C, Sickles EA, Mendelson EB, Morris EA. Breast Imaging Reporting and Data System: ACR BI-RADS breast imaging atlas. 5th ed. Reston, Va: American College of Radiology, 2013 • Chang CB, Lvoff NM, Leung JW, et al. Solitary dilated duct identified at mammography: outcomes analysis. AJR Am J Roentgenol. 2010;194(2):378-382. • Michaels AY, Birdwell RL, Chung CS, Frost EP, Giess CS. Assessment and management of challenging BI-RADS category 3 mammographic lesions. RadioGraphics 2016;36(5):1261–1272.