AOCR Resident Distance Learning Lecture

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AOCR Resident Distance Learning Lecture

• Sponsored by the American Osteopathic College of
  Radiology Education Foundation

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MRI Breast IndicationsWhat, when, howGetting
the ball rolling

• Claire McKay, DO
• MS Imaging Associates
• San Antonio, TX

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Goals

• Understand WHAT MRI breast is and where it came
  from
• Review WHEN MRI breast is appropriate
• Gather information and direction on HOW to begin
  to incorporate an MRI breast program for total
  breast healthcare for patients
• Technique Patient, equipment, protocol
• Interpretation and overview
• MRI Breast challenges
• Biopsy and intervention overview

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Nuts and Bolts

• Technique patient, equipment, protocol
• Interpretation overview
• Challenges
• Biopsy, interventions

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What is MRI Breast?

• With contrast, it is a sensitive (95-98) and
  relatively specific (37-97) modality for breast
• Negative predictive value gt95
• Positive predictive value 56-75
• Sensitive in conjunction with PET
• Sensitivity decreases for DCIS and lobular CA
• Premenopausal specificity varies with menstrual
  phase, glandular tissue
• Adjuvant with mammography, US, PE

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WhatEarly Breast MRI

• 1971 T1 relaxation times longer for tumors than
  normal tissue
• 1979 Breast images produced before brain images
• NY 1983 Breast MRI coils first available
• Germany 1988 Gadolinium contrast used on
  cancers to avoid excisional biopsy
• 1990 Fat suppression with hi-resolution MRI for
  tumor staging
• 1990s Slow adaptation due to poor fat
  suppression, no biopsy tools, poor RF coils

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WhatBreast MRI Coming of Age

• Coils, fat suppression, image processing widely
  available and of quality
• Stereotactic capabilities
• CAD
• MRI compatible needles, markers, wires
• ACR, ACS, ASBD, ASBS Practice Guidelines
• ACR Breast MRI Lexicon

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When Indications

• Tumor workup and staging
• Incomplete workup, occult mammogram and/or US
• Neoadjuvant response, post op margins
• High risk screening
• Implants

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Indications
Breast cancer staging Extent of disease
evaluation prior to breast conservation surgery
or mastectomy planning. Contralateral breast
examination in patients with breast malignancy
MRI can detect unsuspected disease in the
opposite breast in at least 4-5 of breast cancer
patients. Often, with negative mammography and
physical examination. Lesion characterization
When conventional breast imaging studies such as
mammography, ultrasound or physical examination
are inconclusive for the presence of breast
cancer. Large lymph nodes may be
present. Monitoring chemotherapy treatment To
evaluate chemotherapeutic response and the extent
of residual disease prior to surgical treatment
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Indications
Evaluating patients with positive surgical
margins for residual disease To help determine
which patients could be effectively treated by
re-excision or whether a mastectomy is required
due to the presence of more extensive
disease. Silicone and non-silicone breast
implant evaluation Evaluating breast implants
for rupture and detecting cancer in women with
breast implants pre-operative for
implants. Evaluating post-operative scar versus
tumor recurrence Occult breast cancer Locating
the very small, undiagnosed breast cancer (occult
cancer) when a malignant axillary node is found
and the origin cannot be determined with
mammography or physical examination. Surveillance
of high risk patients Breast cancer screening
in patients with a genetic predisposition to
breast cancer.
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What MRI Breast Basics 1

• Radiofrequency pulses with precise spacial
  modulation (use and manipulation) of strong
  magnetic field to image magnetic characteristics
  of hydrogen atoms
• 2-D thin slice, multiplanar or 3-D volumetric
  images without ionizing radiation
• Operator independent, not limited by dense breast
  tissue (relative)

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What MRI Breast Basics 2

• MRI pulse sequences create images that reflect
  different tissue properties
• MRI is very sensitive to paramagnetic IV contrast
  to shorten T1 relaxation increases signal to
  improve tissue differentiation
• Invasive breast tumors have neovascular borders
  thinned/leaky abnormal endothelium leads to rapid
  exchange of the contrast in the tumor compared to
  normal tissue.
• Thus, sensitivity for breast CA gt90
• Morphology and time course enhancement help
  differentiate benign from malignant

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What Breast CA MRI Principles

• Breast cancers are sensitive to contrast
  enhancement regardless of tissue density
• Tumor angiogenesis gives preferential enhancement
  of CA with IV contrast
• Lesion morphology must be used there is overlap
  between B9 and malignant lesions
• Time course enhancement
• Cancers have rapid wash-in in the 1st 2 min
• Cancers have plateau or gradual wash-out
• Cancers peak enhancement approx lt/2 minutes
• Benign conditions generally enhance gradually

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How Patient selection

• Appropriate indication(s)
• Menstrual cycle 7-10d after menstrual onset
• Contraindications vascular clips, ocular metal,
  pacemaker, implanted electromagnetic devices use
  a safety form
• Breast history form complaints, lumps previous
  bxs and clip sizes (signal void, blooming) XRT,
  chemo, surgery dates, HRT, cycle phase, family hx
• Get old films mammograms and US, PET

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How Equipment

• 1.5T magnet provides best STN ratio high
  performance gradients fastest, highest
  resolution.
• 1.5T improves fat suppression
• Not all software is alike shop and try before
  you buy
• Open MRI has weaker gradient systems
• Dedicated breast coil (4,7,8 channel)
• Prone reduces respiratory motion
• Stablizes breasts with little/no compression
• Do not use firm compression
• Coil maximizes STN ratio
• Remote power injector for dynamic imaging

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How Breast Coil RF System

• Parallel
• Multi small receive only coils higher SNR, less
  homogeneity, more hot spots
• Higher resolution but higher SNR, parallel
  artifacts
• Simultaneous acquisition
• Dedicated
• Transmit-receive quadrature coils larger FOV
  lower SNR but more efficient pulse sequence, less
  artifacts
• Broad homogenous coverage, few hot spots

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How Breast Coils
20cm unilat 40cm bilat
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How Breast Coil

• 1. Open Lateral, medial, cranial for
  intervention
• 2. Multichannel Parallel imaging for faster
  scan time and aid in diagnostic and intervention
• 3. Ergonomic Patient comfort careful of
  breast size and axillary imaging
• Integrated light source Ease with intervention
• Size One size fits most

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Dedicated Breast MRI
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How What is Shim?

• Area affected for image in a coil
• Factory round vs ellipsoid
• Round Each breast region of interest
• Ellipsoid Spherical FOV

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How Protocols

• Protocols are individualized for equipment
• Vendors have software
• Pulse sequences Gradient echo, spin echo, 3D,
  2D, fat sat /- subtraction, post contrast
  dynamic scans, time interval between postcontrast
  scans, matrix, scan time, slice thickness
  ax-sag-cor
• Postprocessing Multiplanar recons, MIP, time
  intensity curves
• Scan time 30 minutes postprocessing
• CAD cuts postprocessing time

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How Protocol/Interpretation

• T1 Skin, fibroglandular tissue, muscle, LN
• Moderately low signal compared to fat
• Mammary gland mixed low signal in high signal fat
  lobules
• Also includes lipoma, protein cyst
• T2 Heterogenous fibroglandular higher signal to
  muscle high signal cysts, lymph nodes,
  papilloma, ducts, blood vessels especially at
  periphery
• T1 fat sat post Enhance peripheral SQ vessels,
  nipple, tumor enhancement
• Dynamic post Fibroglandular tissue gradual,
  invasive cancer and lymph nodes rapid uptake
• Signal Time Intensity Curve

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T1 ax VIBRANT pre/fatsat
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Sag T2 FSE
Post op
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Fast STIR T2
Implant leakage, incidental pleural R effusion.
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T1 Post contrast Dynamic X4
Ax Post Sub
Cor Post Sub
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MIP 3D Post XRT Left Breast
L
R
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Portfolio with multiple nodules
Enhancement Curves
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3D MIP fatsat/subtraction IDC
Pre chemo
Post chemo 4 mo
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Portfolio pages pre - post
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How Artifacts

• Ghosting cardiac or respiratory motion
• Poor fat suppression from poor shim or excitation
  center frequency
• Patient motion causes blur or bright/dark bands
• Poor enhancement from failed contrast injection
• Metal void or blooming

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Shim
Blooming
Breathing motion large breasts
Ghosting, blooming
Artifacts
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What is a Time Intensity Curve?

• Goal To evaluate the enhancement pattern of a
  lesion
• ROI placed selectively onto lesion(s)
• Signal intensity (SI) is plotted on the SI Time
  Course
• To identify the part of the lesion with the
  strongest and fastest enhancement
• Manual vs CAD
• Selective information for differential diagnosis

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Persistent
Plateau
Bowed
There is overlap. Nothing replaces morphology
PLUS enhancement in interpretation.
Washout
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How ACR Lexicon

• Lesion Focus, mass, linear, ductal,
  focal/segmental/regional/diffuse, clumped,
  heterogenous/homogeneous, reticular,
  symmetric/asymmetric
• Shape Round, oval, lobulated, irregular
• Margins Smooth, irregular, spiculated
• Other Nipple retraction, skin thickening, edema,
  ducts, cysts, signal void
• Signal pattern
• Initial rise lt/ 2 min slow, medium, rapid
• Enhancement background, persistent, plateau,
  washout
• BIRADS Breast MRI BIRADS should be used

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When do I need MRI Biopsy or MRI guided Needle
Loc?

• Nonpalpable imaging detected breast lesion
• Accurate and safe targeting
• Real lesion
• Cooperative patient
• Well visualized in 2 views
• Safe lesion access

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In the beginning

• Sagital T2
• T1 pre and post fat saturation axial
• Axial dynamic imaging post contrast
• Coronal post contrast
• Post processing thin mip and 3-D
• Implant spin echo axial
• Gadolinium is necessary for cancer detection

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How Interpretation
Morphology
Probably B9
Suspicious
Benign
KINETICS
Plateau or bowed curve
Persistent curve
Short term follow up
Biopsy
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37yo with 100 lb weight loss new palpable mass
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Ax Post T1 fat sat
Ax 3D MIP fat sat sub
DCIS
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Ax 3D MIP fat sat sub post
Ax T2 STIR (implant rupture)
Sag T2
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Sag T2
Ax T1 post fat sat
43yo post excisional bx seroma MRI to check for
residual disease
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Screening MRI High Risk Family Hx
Pre contrast
Post contrast
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IDC
Benign tissue
Slow, persistent
Rapid, plateau
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Sag T2
55yo Prior R mastectomy, implants, new nodule on
L on annual mammogram
3D MIP post
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47 yo, prior mastectomy, breast pain, f/u 4mm
nodule
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6 mop fu nodule R 6 ocl stable MRI bx B9
stromal, florid UDH
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60 yo for known DCIS R 3 ocl MRI prior to
surgical excision
2 additional nodules found R
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3D MIP DCIS portfolio Irregular, lobular enhance
rapid, plateau
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DCIS R with additional nodules medial irregular,
enhancement rapid, plateau
MRI biopsy Stromal fibrosis, FCC, calcifications
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MRI Breast Challenges

• Resolution DCIS, lobular carcinomas
• Interpretation Few normals, time consuming, CAD
  confusion, difficult to correlate with mammogram
  and US and clinical information plus old films
• Time Pulse sequences longer scan time, post
  processing
• Cost Does the information justify the cost?
  Does it increase biopsies?
• MRI intervention Expensive tools, time consuming
  in the MRI suite, lesions access
• NOT meant to replace mammography

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Thank you !
cmckayhart_at_juno.com