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MRI Breast (Screening/Diagnostic)

Dynamic contrast-enhanced breast MRI is the most sensitive imaging test for invasive breast cancer and is used for high-risk screening, disease extent assessment, and problem-solving. It relies on tumor neoangiogenesis producing early enhancement and characteristic kinetics, interpreted alongside morphology using the BI-RADS lexicon. It also evaluates silicone implant integrity without contrast. Careful attention to background parenchymal enhancement and timing is essential for accurate interpretation.

Indications

  • Annual high-risk screening (BRCA/other mutation carriers, prior chest radiation, strong family history, lifetime risk >=20%)
  • Assessment of extent of disease and multifocal/multicentric/contralateral disease in newly diagnosed cancer
  • Problem-solving of equivocal mammographic/ultrasound or clinical findings
  • Evaluation of response to neoadjuvant chemotherapy
  • Assessment of the primary in occult breast cancer presenting with axillary metastasis
  • Silicone implant integrity evaluation (non-contrast protocol)
  • Evaluation in dense breasts where mammographic sensitivity is reduced

Contraindications & Cautions

  • Non-MRI-conditional implanted devices and ferromagnetic foreign bodies
  • Severe renal impairment (eGFR <30) limits gadolinium; nephrogenic systemic fibrosis risk
  • Gadolinium hypersensitivity
  • Pregnancy: avoid gadolinium; breast MRI generally deferred
  • Timing in premenopausal women: schedule days 7-14 of the menstrual cycle to reduce background enhancement
  • Inability to lie prone and still for the examination

Patient Preparation

  • MRI safety screening for devices and implants
  • Schedule during the second week of the menstrual cycle in premenopausal women
  • Review the value of pausing hormone replacement therapy per local protocol
  • Check eGFR and obtain contrast consent
  • Establish reliable antecubital IV access for power-injected gadolinium
  • Position prone with both breasts pendant in a dedicated bilateral breast coil
  • Ensure comfortable, symmetric positioning to minimize motion and enable subtraction

Technique & Parameters

  • 1.5T or 3T (3T preferred) with a dedicated bilateral breast coil, prone positioning
  • Bilateral axial T2/STIR for cysts, edema, and lymph node characterization
  • Axial T1 fat-suppressed pre-contrast, then multiple dynamic post-contrast acquisitions (early ~90 s and delayed phases)
  • Subtraction images and maximum intensity projections for lesion detection
  • High spatial resolution with <=1 mm in-plane and thin slices for morphology
  • Diffusion-weighted imaging as an adjunct to improve specificity
  • For implants: T2 with silicone-selective and water-suppressed sequences, no contrast required

Systematic Review

  • Assess and grade background parenchymal enhancement (minimal, mild, moderate, marked)
  • Review MIPs and subtractions for foci, masses, and non-mass enhancement
  • Characterize each enhancing lesion by morphology (shape, margin, internal enhancement)
  • Analyze kinetic curves (initial upstroke and delayed washout/plateau/persistent)
  • Compare with mammography/ultrasound and prior MRI for stability
  • Evaluate the axillary, internal mammary, and supraclavicular nodes
  • For implants, assess for intra/extracapsular rupture signs
  • Inspect skin, nipple, chest wall, and imaged lung/mediastinum

Key Findings & Significance

  • Irregular mass with spiculated/irregular margins and rim enhancement with washout kinetics suggests malignancy
  • Segmental or linear clumped non-mass enhancement suggests DCIS or invasive disease
  • Persistent enhancement with smooth oval morphology favors a benign lesion (e.g., fibroadenoma with nonenhancing septa)
  • Washout kinetic curve (type 3) increases suspicion; persistent (type 1) is more often benign
  • Linguine sign indicates intracapsular implant rupture; free silicone indicates extracapsular rupture
  • Marked background parenchymal enhancement can mask lesions and reduce specificity
  • Enlarged, rounded, cortically thickened axillary node suggests nodal metastasis

Differential Considerations

  • Enhancing mass: invasive carcinoma, fibroadenoma, papilloma, phyllodes, lymph node
  • Non-mass enhancement: DCIS, invasive lobular carcinoma, fibrocystic change, hormonal/background enhancement
  • Rim-enhancing lesion: invasive carcinoma, fat necrosis, abscess, inflamed cyst
  • Washout kinetics: malignancy, but also some fibroadenomas and papillomas
  • Implant abnormality: intracapsular rupture, extracapsular rupture, radial folds (mimic), silicone granuloma
  • Multiple enhancing foci: benign hormonal enhancement vs multifocal malignancy

Pearls & Pitfalls

  • Morphology outweighs kinetics; assess both but do not dismiss a suspicious mass with benign curves
  • Marked background enhancement reduces sensitivity/specificity; time to cycle phase when possible
  • Subtraction misregistration from motion can create false enhancement; verify on source images
  • Fat necrosis and post-surgical change commonly mimic malignancy; correlate with history and T1 fat signal
  • Nonenhancing internal septa in an oval mass are characteristic of fibroadenoma
  • Do not overlook the axilla and internal mammary chain
  • MRI-detected lesions without a correlate may require MRI-guided biopsy

Structured Report

  • State indication, technique, cycle timing, contrast, and comparison studies
  • Report background parenchymal enhancement and fibroglandular density
  • Describe each lesion using BI-RADS lexicon (morphology, internal enhancement, kinetics, size, location)
  • Assign a BI-RADS final assessment category and management recommendation
  • Report nodal, skin, nipple, and chest wall involvement
  • For implants, state integrity and rupture type if present
  • Impression: most significant finding, correlation needs, and biopsy/follow-up recommendation

References

  • ACR BI-RADS Atlas (MRI) lexicon and assessment categories
  • ACR Practice Parameter for the Performance of Contrast-Enhanced Breast MRI
  • ACS/ACR high-risk breast MRI screening guidelines
  • EUSOBI recommendations for breast MRI
  • RadioGraphics reviews on breast MRI interpretation, kinetics, and implant evaluation

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.