Breast MRI

Indications for Breast MRI

  • Implant evaluation

  • Axillary mets of unknown primary

  • Evaluate extent of disease (particularly of invasive lobular carcinoma)

  • Evaluate response to therapy

  • High risk screening

    • Lifetime risk >20% (15-25%)

    • 20 Gy of radiation to the chest as a child (lymphoma, etc.)

  • Diagnostic dilemma

  • Protocol

    • Basically everything is fat suppressed because breast is fatty so you need to get normal tissue suppressed

    • T2 with FS —> good to see the benign shit typically, cysts and whatever

    • To identify sequence — no heart visualized = T2

    • Need a breast coil

    • Need to be positioned correctly

Fat saturation

  • Poor fat saturation in image below

  • Remember, cannot use an inversion sequence if you are giving gadolinium because it has similar inversion time as fat (STIR) it would null out the gadolidium

  • Need a homogenous field to tell difference in resonance between fat and water

    • Water typically has taller peak

    • Fat has lower peak

    • Can null the fat peak or

    • Can use shimming

    • Also, get rid of field inhomogeneities (flatten fat fold with air pocket for example)

Incomplete fat saturation

Background Parenchymal Enhancement

  • Varies based on many factors, including

    • Menstrual cycle

    • Contrast agent used

  • Optimal time to scan = between day 5-15 of menstrual cycle

    • More enhancement seen in later part of cycle

    • Need to scan on same time of cycle if a second exam

  • Need to be off hormonal replacement therapy for 2-3 months

  • Need to be at least 6 months after lumpectomy

  • Need to be at least 1 year after radiation therapy

Type 1 = good

Type 3 = bad

Kinetics not really helpful for DCIS

Breast Pathology Pearls

  • Nipple normally enhances but will enhance more in Pagets

  • Enhancement alone does not necessarily indicate malignancy

    • LN, fibroadenomas, papillomas can all enhance

  • If lesions is T2 bright = likely benign

    • Exception = mucinous (colloid) cancer = bright on T2 and malignant

  • Mass margin is the feature most indicative of malignancy (more so than enhancement, bright/dark shit)

    • Margin of the mass should be evaluated on the first post contrast series

    • Spiculated = highest PPV of malignancy

  • Rim enhancement = bad

Foci

  • Dot of enhancement <5 mm

  • Too small to otherwise characterize

  • Multiple enhancing foci is lumped in with the background enhancement, not a BR2 just background breast tissue basically

References:

Flaring

  • Non uniform fat suppression when breast tissue to too close to the coil

  • NOT related to fat suppression process itself

  • Fix by putting a pad between the breast tissue and coild

Kinetics

Pathology

Pulsation artifact

  • Occurs in phase encoding direction

    • Takes longer so done in shorter axis

    • In chest MR = AP

    • In breast MR = side to side

      • Even though sided to side is wider and therefore will take longer you cannot have artifact in front of the chest in the breast tissue

Non-mass enhancement

  • Weird clump like area of enhancement

  • Classified according to distribution

    • Distribution of NME is the most predictive feature

    • Segmental distribution has the highest PPV

    • More concerning patterns

      • Focal

      • Linear

      • Segmental

    • Less concerning patterns

      • Regional

      • Multiple regions

      • Diffuse

  • If you see NME, think DCIS

Fibroadenoma

  • Well circumscribed mass

  • T2 bight (varies)

  • T1 post = homogenous enhancement with non-enhancing septations

Rebound/Flare Affect

  • When on tamoxifen breast tissue is suppressed

  • When off tamoxifen breast tissue will go back to normal and get bigger