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.



  • 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)


  • 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)


  • 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


  • 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


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