Breast MRI

Radswiki et al.

Breast MRI is a rapidly growing field, especially in the assessment of high risk women. 

Editorial board note: this article is probably outdated, lacks structure and is in need of a major rewrite. If you are interested in refining it you are more than welcome.

  • T1
  • T2
  • T1 C+ (Gd) : dynamic and kinetic analysis
  • density
  • background enhancement
    • none/minimal: <25%
    • mild: 25-50%
    • moderate: 50-75%
    • marked : >75%
  • focus < 5 mm: cannot characterize margins, etc
  • mass enhancement
    • shape: round, oval, lobulated, irregular
    • margins: smooth, irregular, speculated
    • internal: homogenous, heterogenous, rim, dark or enhancement, internal septations, central (target)
  • non mass enhancement
    • focal, linear ductal, linear clumped, segmental patchy/clumped, regional, diffuse
    • stippled, punctate, bilateral symmetric - it is important to scan both breasts for comparison
  • linear enhancement
  • enhancement kinetics: see breast MRI enhancement curves
    • washout, plateau, persistent (caveat: papillomas and lymph nodes washout)
    • ~ 70% of invasive cancers wash out 
    • ~ 9% of DCIS washes out
  • BIRADS 0: use very sparingly; confirming lymph node or fibroadenoma on ultrasound or confirming benign process on mammogram and mammogram not available
  • BIRADS II: lymph nodes, inflamed cysts, fibroadenoma, fat necrosis, foci/stippled enhancement, background enhancement.
  • BIRADS IIIA: short term follow-up (in 1-3 months) no mass likely hormonal enhancement (day 7-14 unless patient has known cancer for EOD eval or 2 - 3 weeks off hormone replacement therapy)
  • BIRADS IIIB: 6 month follow-up for mass enhancement after having evaluated for benign morphology and kinetics; probably benign: < 5 mm without rim enhancement, spiculation or washout
  • BIRADS IIIA & B: follow for 2 years (6 month, 1 year, 2 year. (whereas mammogram 3 years; 24% of 1st time MRI given BI-RADS 3; 0-10% cancer rate (3% MSKCC; small invasive cancers and DCIS)

It is important to remember that as most MRIs of the breast are performed on high risk population, 17% of smooth masses on 1st MRI were cancer (2/3 DCIS/ 1/3 Invasive). Thus one must not apply the same rules as to ultrasound on low risk patient; i.e. if washes out the lesion needs to be biopsied. 

Similarly ductal enhancement should always prompt a biopsy.

Clinical history and correlation with mammography is always useful and can reduce assignment of BIRADS III category.

Cancer detection highest in postmenopausal and for extent of disease (EOD) evaluation (22%) and lowest in premenopausal women for high risk screening (10%)

Positive predictive value (PPV) of MRI
  • in high risk screening population : 3 - 4% prevalence when mammography was negative ( 0.3 % when mammo and ultrasound negative)
  • 7% if personal history of cancer
  • positive predictive value 24% ( ½ invasive 4 mm median size/ ½ DCIS). Biopsy recommended in 17%
Extent of disease (EOD)
  • contralateral breast
    • 5% prevalence
    • 20 % positive predictive value (biopsy recommended in 1/3) (NEJM 3/29/07: Bx rec in 12 % PPV 25 %);
  • Ipsilateral breast
    • ~ 25%
    • 50% PPV (biopsy recommended in 50%)

Ipsilateral multifocal ¾ (same quadrant > 1cm from index CA or contiguous but extends > 4 cm) multicentric ¼; distribution similar to recurrent disease

Additional sites of ipsilateral cancer more frequent if +FH (42%) & ILC (55%)

Positive predictive value higher the closer the lesion is to the index cancer.

Biopsy to get histological diagnosis no matter how suspicious because result is Mx

Younger patients because of 1 - 2% / year recurrence may also benefit from preop MRI

True and false positive rate decreases with each subsequent comparison MRI

MRI sensitivity
  • IDC / ILC : > 90%
  • DCIS : 80 - 90%
  • Implant rupture : ~ 94 % 9
ACR guidelines
  • high risk screening
  • extent of disease (EOD) evaluation in ipsilateral and contralateral breast
  • positive margins (better accuracy further from lumpectomy site than near Lx site b/c postop enh/changes)
  • neo-adjuvant chemotherapy : to assess residual disease
  • metastatic axillary lymphadenopathy of unknown primary (75 - 80% sensitive) - can spare a patient from having management because may be able to undergo BCT; management path only finds cancer in two-thirds
  • posterior lesion to assess chest wall invasion (pectoralis can be resected so not considered
  • chest wall stage IIIB - serratus anterior, rib, intercostal muscles)
ACS recommendations
  • BRCA+ : BRCA 1 or BRCA 2
  • 1st degree relative BRCA+ and untested
  • those who have had prior radiotherapy to chest wall 
  • > 25% lifetime risk based on genetic models (some of which take breast density into consideration)
  • not recommended if lifetime risk < 15 % because of high false positive rate
Other possible indications
  • problem solving (e.g. post operative breasts with distortion)
  • recurrent breast cancer / scar changes (not usual before 2 - 3 years; peak 5 - 7 years; increased risk if EIC, younger age, positive margins (wait at least 1 month post op to scan), no RT)
  • to assess for synchronousmultifocal or multicentric disease
Mass
  • spiculated mass : 80 %
  • irregular shape : 32 %
  • < 5 mm mass : 3 %
Non mass
  • calcifications
    • segmental : 67 %
    • clumped ductal : 31 %
Ductal enhancement
  • malignant causes : DCIS, invasive cancer
  • benign high risk causes : ADH, LCIS
  • benign : fibrosis, ductal hyperplasia, fibrocystic change
  • 40 - 50 % cancers should be < 1 cm
  • at least 20 - 30% should be DCIS
  • positive nodes < 20%
False negatives
  • technical causes : breast tissue not included in the coil, motion, bad contrast injection, too much compression
  • marked background enhancement

Caveat : if mammography or ultrasound is positive or palpable finding need to treat / biopsy / excise despite negative MRI !

Ultrasound correlation

MSKCC : only 23% probably low but if lesion is less than 1 cm or deep within lots of background parenchyma in a large breast may want to go directly to MR guided biopsy.


Breast imaging and pathology
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Article Information

rID: 12182
Systems: Breast, Oncology
Section: Approach
Synonyms or Alternate Spellings:
  • MRI breast
  • MRI of the breast
  • Magnetic resonance imaging of the breast

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  • Drag
    VIBRANT +C early ...
    Case 1 : showing breast cancer + lipoma
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    3D VIBRANT +C
    Case 2 : showing invasive ductal carcinoma
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    Case 3 : showing invasive lobular carcinoma
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    Fig. 1

Sagittal T2
    Case 4 : showing extra-capsular implant rupture
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    Subtraction image
    Case 5 : showing multicentric lobular cancer
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    CAD colour flow m...
    Case 5 : color coded image shows large breast cancer
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    On post contrast ...
    Case 6: pseudoangiomatous stromal hyperplasia
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    This is a type I ...
    Case 7: enhancement curve
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    Case 8: high grade ductal carcinoma in situ
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