Mr Bi-Rads Lexicon



Mr Bi-Rads Lexicon


Sughra Raza, MD










Sagittal T1WI C+ FS MR in a 65 year old with a mass on screening mammogram shows an oval mass with spiculated margins and thick rim enhancement image (BI-RADS 4C). US-guided CNB revealed IDC and DCIS.






Sagittal T1WI C+ FS MR of the opposite breast in the same patient shows unexpected ductal, clumped NMLE image (BI-RADS 4B). MR-guided CNB showed IDLC.


TERMINOLOGY


Abbreviations



  • Breast imaging reporting and data system for magnetic resonance imaging (BI-RADS® MRI)



    • Published by American College of Radiology (ACR); terms may undergo revision


  • Maximum intensity projections (MIP)



    • 3D reconstruction of brightest pixels from 3D post-contrast subtraction data


  • Computer-aided detection (CAD)



    • Computer-assisted parametric mapping


  • Signal intensity (SI)


Definitions



  • Standardized terminology developed by subcommittee of ACR



    • Terms parallel BI-RADS: Mammography and BI-RADS: US when possible


    • Lexicon to describe findings on breast MR



      • Lesion type, architecture, and location


      • Kinetics: Initial and delayed phase


      • Associated findings: Nipple, skin, axilla, chest wall


      • Final assessment and management recommendations


      • Extramammary findings (e.g., hepatic, pulmonary)


  • Focus: Punctate, nonspecific enhancement, too small to characterize morphologically (usually < 5 mm)


  • Mass: Enhancing 3D space-occupying lesion with discrete margins


  • Non-mass-like enhancement (NMLE): Area of enhancement distinct from surrounding parenchyma; not space-occupying mass



    • Usually has interspersed fat or normal tissue


  • Kinetics: Signal-intensity curves based on initial and delayed-phase enhancement over time



    • Sensitivity threshold (e.g., 50%, 60%, 100% increase in signal intensity in 1st 90 seconds) determines whether or not color is assigned


    • Specific color assignment is based on delayed-phase behavior (persistent, plateau, washout)


MR FEATURES & INTERPRETATION Imaging Protocols



  • Magnet field strength of at least 1.5 T


  • Dedicated breast coil


  • Sequences



    • Typically: T1W image; T2W FS image (or STIR); dynamic pre- and post-contrast 3D SPGR FS


  • Contrast: 0.1 mmoL/kg Gadolinium-based contrast via power injector


  • Post-processing: Subtraction series, MIPs, ± use of CAD


Imaging Pitfalls



  • Limitations of examination



    • Confirm successful contrast administration (e.g., heart, great vessels, liver enhancement)


    • Hormonal influences: Significant variation can be seen in parenchymal enhancement in premenopausal women



      • Schedule in days 7-14 of menstrual cycle when possible: ↓ parenchymal enhancement, false positives


    • Larger breasts: Inhomogeneous fat saturation; artifacts from breast touching coil or table surface


Exam Interpretation



  • Interpretation informed by exam indication, history, and correlative imaging findings



    • Prior biopsies, risk factors, ± symptoms


    • Compare to recent mammography, US, and MR


  • Lesion location



    • Quadrant, subareolar, central, axillary tail


    • Distance from nipple, skin, or chest wall (in cm) as appropriate


    • Table position (e.g., R72) &/or series/slice location where finding best seen


  • Background enhancement



    • Minimal, mild, moderate marked


    • Moderate background enhancement may obscure detection of small masses


    • Parenchyma usually slower to enhance than cancer



      • Early imaging (within 1-2 minutes) after contrast injection is therefore important



Mass Shape



  • Round/spherical; oval/elliptical


  • Lobulated: Undulating contour, scalloped


  • Irregular: Uneven shape


Mass Margin



  • Smooth: Circumscribed, 17-44% malignant when solitary



    • Resolution of ˜ 1 mm may be insufficient to identify subtle spiculation


  • Irregular: Neither smooth nor spiculated, may be ill defined or indistinct; 22-39% malignant


  • Spiculated: Radiating lines from margin, 80-91% malignant


Mass Internal Enhancement Characteristics



  • Homogeneous: Confluent, uniform enhancement


  • Heterogeneous: Nonuniform enhancement


  • Rim enhancement: Greater at periphery, 40-84% malignant



    • Thick, irregular rim, rapid enhancement, and washout kinetics favor malignancy


  • Enhancing internal septations: PPV > 95%


  • Central enhancement: Greater in center of mass


  • Dark internal septations: Nonenhancing internal septations



    • High NPV; often fibroadenomas


Non-Mass-Like Enhancement (NMLE) Distribution



  • Focal area: < 25% of quadrant in confined area



    • Contains interspersed fat or normal glandular tissue


  • Linear/ductal: In a line, pointing to nipple; often branching, conforming to duct



    • Linear often used in place of ductal


    • 20-26% malignant, usually clumped internal enhancement


  • Segmental: Triangular region or cone with apex pointing to nipple



    • Suggests duct and its branches


    • Most common NMLE reported in DCIS at 40-55%


  • Regional: Geographic, ≥ 25% of quadrant



    • Symmetric regional NMLE favors benign etiology


    • At edges of parenchyma: May be “inflow”


    • Cyclic dependency if normal variant


    • When isolated and biopsied, 47-50% malignant


  • Multiple regions: ≥ 2 regions, patchy


  • Diffuse: Uniform, even throughout breast



    • Distinguish diffuse NMLE from background enhancement


NMLE Internal Enhancement



  • Heterogeneous


  • Homogeneous


  • Clumped: Cobblestone-like, confluent in areas, “bunch of grapes” or “string of pearls” appearance



    • Favors DCIS, especially in linear or segmental distribution


  • Stippled/punctate: Round, tiny, dot-like


  • Reticular/dendritic: Strand-like



    • Can be seen with inflammatory carcinoma


NMLE Symmetry



  • Symmetric: Mirror image, both breasts


  • Asymmetric: More in 1 breast than other


Kinetics



  • Sample and report ROIs of most rapidly enhancing ± most suspicious areas in lesion


  • Initial phase: Change in SI within 1st 2 minutes of injection (before curve changes)



    • Slow: < 60% increase in SI


    • Medium: 60-100% increase in SI


    • Rapid: > 100% increase in SI


  • Delayed phase: SI over time after 1st 2 minutes



    • Persistent (type 1): Progressive, continued increase in signal over time


    • Plateau (type 2): SI does not change over time after initial rise; flat (± 10%)


    • Washout (type 3): SI decreases after peaking



      • Cancers more likely to show washout or plateau kinetics



Associated Findings



  • Nipple retraction or inversion, pre-contrast high duct signal, skin retraction, skin thickening (> 2 mm), edema, abnormal signal void (artifacts), cyst(s)


  • Lymphadenopathy: Enlarged, rounded nodes, eccentrically thickened cortex, loss of fatty hila



    • Encourage positioning to include axilla


  • Pectoralis muscle or chest wall invasion: Must see extension of suspicious enhancement into pectoralis, intercostal muscle(s), or rib(s); not sufficient to abut


  • Hematoma/blood: Bright signal on pre-contrast T1W image


  • Cyst: Circumscribed round or oval fluid-filled mass, imperceptible wall, bright on T2W FS image


Final Assessments, Recommendations



  • Should reflect the most suspicious findings in each breast


  • 0: Incomplete, additional evaluation needed


  • 1: Negative, no lesion found, routine follow-up


  • 2: Benign finding, routine follow-up


  • 3: Probably benign, short interval follow-up



    • 6-month follow-up



      • 2-10% risk of malignancy across multiple series, varying criteria


      • Concept requires further validation for MR


      • Consider circumstances of exam: Higher risk of malignancy if satellite to known cancer; follow-up problematic due to planned pregnancy or relocation


    • Proposed criteria for BI-RADS 3 (ACRIN 6666)



      • 1-2 smooth, oval mass(es), persistent or plateau kinetics, not suspicious on mammography or US


      • Solitary focus, persistent or plateau kinetics (1/37 [3%] malignant in 1 series)


      • Patchy regional enhancement, persistent kinetics, no US correlate


      • Multiple, bilateral similar findings favor benign


    • Optional 3A: Possibly hormonal, follow-up at different time in cycle, 2-6 weeks


  • 4: Suspicious abnormality, optional subdivision



    • 4A: Low suspicion of malignancy, biopsy


    • 4B: Intermediate suspicion of malignancy, biopsy


    • 4C: Moderate suspicion of malignancy, biopsy


  • 5: Highly suggestive of malignancy, take appropriate action (usually biopsy)


  • 6: Recent biopsy-proven malignancy; ongoing treatment



    • Exam for local extent of disease


    • Following neoadjuvant chemotherapy



REFERENCES

1. Schnall MD et al: Diagnostic architectural and dynamic features at breast MR imaging: multicenter study. Radiology. 238(1):42-53, 2006

2. Morakkabati-Spitz N et al: Diagnostic usefulness of segmental and linear enhancement in dynamic breast MRI. Eur Radiol. 15(9):2010-7, 2005

3. Kriege M et al: Efficacy of MRI and mammography for breast-cancer screening in women with a familial or genetic predisposition. N Engl J Med. 351(5):427-37, 2004

4. Warner E et al: Surveillance of BRCA1 and BRCA2 mutation carriers with magnetic resonance imaging, ultrasound, mammography, and clinical breast examination. JAMA. 292(11):1317-25, 2004

5. Ikeda DM et al: Breast Imaging Reporting and Data System, BI-RADS: Magnetic Resonance Imaging (BI-RADS®: MRI), 1st ed. Reston, American College of Radiology, 2003

6. Liberman L et al: Ductal enhancement on MR imaging of the breast. AJR Am J Roentgenol. 181(2):519-25, 2003

7. Liberman L et al: Probably benign lesions at breast magnetic resonance imaging: preliminary experience in high-risk women. Cancer. 98(2):377-88, 2003

8. Liberman L et al: Breast lesions detected on MR imaging: features and positive predictive value. AJR Am J Roentgenol. 179(1):171-8, 2002

9. Nunes LW et al: Optimal post-contrast timing of breast MR image acquisition for architectural feature analysis. J Magn Reson Imaging. 16(1):42-50, 2002

10. Ikeda DM et al: Development, standardization, and testing of a lexicon for reporting contrast-enhanced breast magnetic resonance imaging studies. J Magn Reson Imaging. 13(6):889-95, 2001

11. Schnall MD et al: A combined architectural and kinetic interpretation model for breast MR images. Acad Radiol. 8(7):591-7, 2001






Image Gallery









Axial T1WI C+ FS MR with color overlay in an asymptomatic 33 yo woman, whose sister had breast cancer at 39, shows an 8 mm oval, smooth mass with rapid initial enhancement & washout kinetics image.






Sagittal T1W FS MR C+ delayed image shows washout kinetics image. On T2W image (not shown) the mass demonstrated high signal (BI-RADS 4B). MR-guided CNB showed a grade II IDC.






(Left) Sagittal T1WI C+ FS MR in a 50 yo woman with family history of breast cancer shows a < 5 mm focus image. A few other small foci were also present; mammograms had been negative for 7 years. (Right) Sagittal T1WI C+ FS MR with color overlay (same patient) shows washout kinetics image. Follow-up MR at 6 months was recommended (BI-RADS 3). Despite the size (< 5 mm), this is a mass with irregular margins &, in retrospect, should have been biopsied.






(Left) Sagittal T1WI C+ FS MR in the same patient at 6-month follow-up shows increased lesion size, now reported as a 5.5 mm mass with more intense enhancement image and irregular margins. (Right) Sagittal T1WI C+ FS MR image from the same exam shows washout kinetics only in the small mass image (BI-RADS 4B). Biopsy showed an ER(+), PR(+), Her-2/neu(-), grade I IDC and DCIS. She was treated with lumpectomy, XRT, and tamoxifen.






(Left) Axial T1WI C+ FS MR of a 48-year-old woman with history of right breast ADH on excisional biopsy shows a solitary 3 mm focus in the medial posterior left breast image. (Right) Sagittal T1WI C+ FS MR delayed image of the same patient shows plateau kinetics image (BI-RADS 4B). Correlative US showed a 4 mm mass and US-guided CNB revealed an ER(+), PR(+), Her-2/neu(-), grade II IDC with DCIS.







(Left) Axial T1WI C+ FS MR in a 71-year-old woman with a new palpable lump in the upper right breast, corresponding architectural distortion on mammogram, and shadowing mass on US shows nonenhancing distortion image. This patient had a remote history of excisional biopsy near this site. (Right) Sagittal T1W FS MR C+ delayed image of the same case shows the focal architectural distortion without appreciable enhancement image.
Only gold members can continue reading. Log In or Register to continue

Related Posts

Sep 18, 2016 | Posted by in OBSTETRICS & GYNAECOLOGY IMAGING | Comments Off on Mr Bi-Rads Lexicon
Premium Wordpress Themes by UFO Themes