BI-RADS and Breast MRI Kathy Borovicka, M.D. Thursday February 15, 2018
Learning Objectives Be familiar with the Breast Imaging Reporting and Data System (BI-RADS) Understand the components of a breast imaging report, including the description of breast density, description of important findings, assessment and management. Be familiar with the indications for breast magnetic resonance imaging (MRI) Understand the terminology used in reporting the findings for breast MRI including mass and non mass enhancement
BI-RADS Breast Imaging Reporting and Data System American College of Radiology Most recent: 5th Edition (2013) Communication among physicians using common terminology with clear, concise, and standardized reporting Mammmography, US, MRI Follow up and outcome monitoring
BI-RADS 0: Incomplete assessment 1: Negative. 2: Benign 3: Probably benign 4: Suspicious 5: Highly suspicious 6: Known carcinoma
BI-RADS 0 Usually given for screening examinations with additional imaging recommended. Or possibly request for comparison with prior examination(s) within 30 days The radiologist describes the additional mammography views and ultrasound if needed on the call back form
BI-RADS 1 & 2 BI-RADS 1: Negative BI-RADS 2: Benign calcified fibroadenomas, skin calcifications, metallic foreign bodies (core biopsy and surgical clips), fat containing lesions (oil cysts, lipomas, galactoceles, and hamartomas) intramammary lymph nodes, vascular calcifications, architectural distortion from prior surgery, implants Recommend routine mammography screening Essentially 0% likelihood of malignancy
BI-RADS 3 Probably benign Short-interval (typically 6 month) follow up to demonstrate at least 2 year stability Greater than 0% to less or equal to 2% likelihood of malignancy Noncalcified circumscribed solid mass, focal asymmetry, and a solitary group of punctate calcifications
BI-RADS 4 Suspicious Can be further categorized into: 4A: Low suspicion of malignancy: > 2% to 10% likelihood of malignancy 4B: Moderate suspicion of malignancy: > 10% to 50% likelihood of malignancy 4C: > 50% to than 95% likelihood of malignancy
BI-RADS 5 Highly suggestive of malignancy Tissue diagnosis 95% likelihood of malignancy Identifies lesions for which any non-malignant percutaneous tissue diagnosis is automatically considered discordant, resulting in the recommendation for repeat (usually surgical) biopsy
BI-RADS 6 Known biopsy proven malignancy Reserved for examinations performed after biopsy proven malignancy in which there are no additional imaging abnormalities other than then known cancer Preoperative breast MRI Surgical excision when clinically appropriate
Breast Imaging Radiology Report 1. Indication for examination History: Personal or Family history of breast cancer Prior biopsies and pathologies including dates 2. Comparison to prior breast imaging 3. Description of overall breast composition 4. Clear description of important findings 5. Assessment 6. Management
Breast Magnetic Resonance Imaging (MRI) Breast MRI has superior sensitivity to detecting malignancy in comparison to mammography and ultrasound Overlap in benign and malignant diseases limits the specificity of breast MRI Higher cost Limited availability
*Indications for breast MRI American Cancer Society and American College of Radiology: Indicators for the performance of breast MRI 1. Preoperative evaluation: extent of disease. Multifocal: multiple foci of disease in one quadrant Multicentric: multiple disease in different quadrants Additional unilateral disease: 10-27% patients Contralateral disease: 3% patients Tumor size is more accurately depicted with breast MRI Helpful: dense breasts, invasive lobular carcinoma, extensive ductal carcinoma in situ, those who will be treated with neoadjuvant chemotherapy
JAOCR. Oct 2017
JAOCR. Oct 2017
Invasive lobular carcinoma Infiltrative growth pattern (single file growth along normal tissue planes) Mammography and ultrasound underestimate the tumor size of invasive lobular carcinoma Posteriorly: MRI helps with detection of invasion into the pectorals musculature (enhancement) as well as chest wall invasion
Indications for breast MRI 2. Post neoadjuvant chemotherapy: decrease the tumor size preoperatively to offer breast conservation axillary mets locally advanced disease Compare the per to post neoadjuvant chemotherapy breast imaging Importance of placement of biopsy markers in case tumor significantly shrinks and no longer seen with imaging
Indications for breast MRI 3. Positive surgical margins, post breast conservation identify the extent of residual disease which aids in surgical planning for re-exision granulation tissue in the tumor post may result enhancement in the early postoperative period the least false-positive results were found when MRI was performed between 35-42 days following surgery (Frei et al.)
Indications for breast MRI 4. Metastatic axillary lymphadenopathy, unknown primary malignancy Usually <1% of all breast carcinoma cases MRI can detect 62-86% of occult primary breast cancer option: breast conservation therapy rather than mastectomy targeted hormonal and chemotherapeutic treatments based on the histology
Indications for breast MRI 5. Silicone breast implant integrity Noncontrast Intracapsular silicone implant rupture: implant envelope degrades but the silicone is still contained by the surrounding fibrous capsule. MRI: subcapsular, linguine, keyhole/noose signs Extracapsular silicone implant rupture: free silicone outside the fibrous capsule within the breast and axilla
MRI: Implants 1. Implant material and lumen type saline silicone 2. Location: retroglandular, retropectoral 3. Abnormal implant contour: focal bulge 4. Implant rupture: intracapsular +/- extracapsular rupture 6. Peri-implant fluid (post-surgical, ialcl: implant-associated anaplastic large cell lymphoma)
Indications for breast MRI 6. Breast cancer screening: MRI is used as an adjunct to mammography in high-risk women Not appropriate for screening in the general average risk population High risk women: BRCA1 and BRCA2 gene mutations and their untested first-degree relatives Prior chest radiation between ages 10-30 Certain syndromes: Lifetime risk for breast cancer >20% as determined by risk models
Insufficient evidence for women with intermediate risk: lifetime risk between 15-20% diagnosis of atypia or lobular carcinoma in situ (LCIS) dense breasts on mammography personal history of breast cancer Case-by-case basis
Indications for breast MRI 7. Equivocal mammography findings Used as a problem-solving tool 3 dimensional localization of a lesion seen on only 1 view: asymmetries, architectural distortions, and equivocal changes in the appearance of prior surgical or biopsy sites Recent study of 115 patients, MRI was 100% sensitive and 92% specific in such a setting Aid in recommendation for short term follow up versus biopsy
MRI Report Indication Technique Amount of intravenous contrast given (Gadavist- weight dependent) Breast density: fat, scattered, heterogeneous, extremely dense Background parenchymal enhancement (BPE): minimal, mild, moderate, marked BPE: symmetric or asymmetric (postradiaton or pathology)
MRI Sequences Localizer Precontrast axial and sagittal T1 T2: fluid sensitive sequence Postcontrast T1 axial fat sat (4) Subtracted images (4) Color images
MRI: Focus Focus: punctate (dot) enhancement, <5mm, no borders, nonspecific, and too small to be characterized morphologically Multiple: background parenchymal enhancement (BPE) with foci separated widely in the breast by normal fibroglandular breast tissue and fat Suspicious: Unique and distinct from BPE, solitary focus, no fatty hilum, washout kinetics, new or increased from prior Benign: not unique when compared to BPE, bright on T2, fatty hilum, persistent kinetics, stable
MRI: Mass 3D space-occupying structure, convex-outward contour Shape: oval (includes lobulated), round, or irregular Margin: circumscribed, irregular, spiculated Internal architecture Internal mass enhancement characteristics: homogenenous (confluent + uniform), heterogeneous (nonuniform), rim enhancement, dark internal separations (suggests a fibroadenoma)
MRI: Margin margin analysis depends greatly on the spatial resolution, such that a not circumscribed margin may appear relatively circumscribed on low spatial resolution scans mammography has extremely high spatial resolution that may not be matched with the current magnets in clinical use today margin and shape analysis should be performed on the first postcontrast image to avoid washout or progressive enhancement of the surrounding tissue
MRI: Non-mass enhancement (NME) Not a focus or a mass Distribution: focal area, linear, segmental, regional, multiple regions, or diffuse Focal area: confined area of the breast, less than a breast quadrant and within a single duct system Linear enhancement: line corresponding to a single duct. Enhancement can be within or surrounding a duct Segmental enhancement: triangular or cone shaped with the apex at the nipple and ducts and their branches extending posteriorly
MRI: NME Regional enhancement: spans at least a quadrant, broader area than a single duct system, may be geographic, and lacks convex-outward contour Mutliple regions: enhancement over at least two broad areas, separated by normal tissue or fat Diffuse enhancement: widely scattered and evenly distributed, similar appearing enhancement throughout the breast fibroglandular tissue Regional, mutiple and diffuse: characteristic of more benign disease, such as proliferative changes, although multicentric carcinoma may have this appearance.
MRI: NME Nonmass enhancements can be further described: homogeneous, heterogeneous, clumped, clustered ring Clumped: aggregate of enhancing foci in a cobblestone pattern that my be occasionally confluent. Clustered ring: rim like enhancement around adjacent ducts. Can also see with fibrocystic changes.
Kinetic Curve Assessment Abnormal enhancement: enhancement of higher signal intensity compared to surrounding normal BPE on a contrast enhanced scan Kinetic technique: dynamic measurement in which the uptake and washout contrast in tissues is monitored for a period of time following contrast injection depends on: perfusion, capillary permeability, blood volume, contrast media distribution volume Tumors: dense, highly permeable vasculature, rapid blood flow, microheterogeneity. Tumors therefore enhance more rapidly and more strongly than normal tissue
Time intensity curve (TIC) The kinetic information is typically expressed as a TIC CAD (Computer assisted device) systems: calculate kinetic information, generating both color maps and graphs Initial phase of enhancement: slow, medium, fast Threshold: 50-100% increase in signal intensity Delayed phase enhancement: persistent, plateau, washout Overall: morphology trumps kinetics
MRI Skin lesions Cysts Fat containing lesions: lymph nodes, fat necrosis, hamartoma, postoperative seroma/hematoma with fat Nonenhanging findings: ductal precontrast high signal on T1W, cyst, postoperative collections (hematoma/seroma), post-therapy skin and trabecular thickening, non-enhancing mass, architectural distortion, signal void from foreign bodies (biopsy markers, surgical clips) Associated feature: skin thickening, skin retraction, skin invasion (direct invasion, inflammatory cancer), nipple retraction, nipple invasion, axillary adenopathy
SUMMARY Be familiar with BI-RADS applying to all breast imaging modalities: mammography, ultrasound, and breast MRI Understand the components of a breast imaging report: Indication, Comparison (PRIORS), Technique (2D or 3D mammogram, US, MRI), Breast density, Important findings, Assessment and Management (BI- RADS). Indications for breast MRI: preoperative evaluation, post neoadjuvant chemotherapy, positive surgical margins post breast conservation therapy, metastatic axillary LAD with unknown primary breast malignancy, silicone breast implant integrity, breast cancer screening in high risk women, and equivocal mammography findings. MRI findings: focus, mass or nonmass enhancement.
References ACR BI-RADS ATLAS 2013 (text and images) Case Report: Breast Implant-Associated Anaplastic Large Cell Lymphoma: Report of 2 Cases and Review of the Literature. Aesthetic Surgery Journal: 2014, Vol 34 (6). 884-894. Clinical indications for breast MRI Applied Radiology: October 2010. Utilization of Breast MRI for extent of disease in newly diagnosed malignancy. JAOCR: October 2017, Volume 6 (4). 5-11.