breast imaging medical school lecture november 18, 2015 susan peddle, md assistant professor...

Breast ImagingMedical School Lecture

November 18, 2015Susan Peddle, MDAssistant ProfessorUniversity of Ottawa

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Overall Objectives

• Review the background and evidence supporting the use of screening mammography, ultrasound (US) and magnetic resonance imaging (MRI)

• Describe Canadian population‐based screening programs, their performance indicators and their costs

• Provide an overview of mammographic abnormalities and their work‐up

• Screening versus Diagnostic mammography

• BI-RADS

• Review of mammographic abnormalities that warrant further work-up

• Diagnostic work-up

• Features of benign versus malignant lesions on ultrasound

• Breast Intervention

• Role of MRI in breast imaging

• Current recommendations for breast screening

Objectives

• Screening versus Diagnostic mammography

Objective 1

• Screening MG: to find cancers smaller than those detected at BSE or CBE

Sensitivity of BSE: Unknown

Sensitivity of CBE: Unknown

Sensitivity of screening MG: 75-90%

• Diagnostic MG: to further evaluate a screen detected abnormality, symptom or clinical finding

Pain

Palpable lump

Nipple Discharge

Others (skin changes, nipple inversion, shrinking breast, enlarging breast)

Screening MG versus Diagnostic MG

pectoralis muscle

inframammary fold

lymph node

fat

glandular tissue

vessel

skin

Cooper’s ligaments

subareolar lactiferous

ducts

Mammographic Mammographic AnatomyAnatomy

Typical Mammography Unit

Routine Mammographic Views

CC

MLO

MLO CC

Upperquadrant

Lowerquadrant

Outerquadrant

Innerquadrant

12:00

9:00 3:00

6:00

MedLat

O’clock Position used for Localization

6:00

3:009:00

12:00

Right Breast Left Breast

Med Lat

Technical Limitations

• Breast Density

• Patient anxiety, discomfort, physical limitations

• Post-therapeutic changes

Breast Density

fatty replaced0-25%

scattered25-50%

heterogeneous50-75%

extremely dense

75-100%

• BI-RADS

Objective 2

BI-RADS

• Breast Imaging Reporting and Data System

• Helps achieve uniformity in breast imaging reports which improves their clinical utility by communicating findings in a standardized way

• Help determine clear management

• 0: Needs further evaluation

• 1: Normal

• 2: Benign finding

• 3: Probably benign

• 4: Suspicious abnormality

• 5: Probable cancer

• 6: Biopsy proven cancer

BI-RADS

• 0: Needs further evaluation - additional mammographic views, +/- US, +/- MRI

• 1: Normal - Return to screening

• 2: Benign finding - Return to screening

• 3: Probably benign - > 98% likelihood of being benign. Short interval follow-up recommended in 6 months.

• 4: Suspicious abnormality - Biopsy needed

• 4A - 10-50% likelihood of being malignant

• 4B - 50-95% likelihood of being malignant

• 5: Probable cancer - Biopsy and surgical consultation needed (> 95% likelihood of being malignant)

• 6: Biopsy proven cancer

• Review of mammographic abnormalities that warrant further work-up

Objective 3

4 Main Mammographic Abnormalities

• Microcalcifications

• Architectural distortion

• Mass

• Asymmetries

Microcalcifications

Microcalcifications• Microcalcifications can be an

indicator of cancer, although they are often benign

• Detected mammographically

• Characterized by morphology (appearance), distribution, and change over time

• Analysis helps radiologist determine the likelihood of underlying benign versus malignant pathology

image

Terminal Ductal Lobular Unit (TDLU)

• Basic functional unit in the breast

• Consists of 10-100 acini that drain the terminal duct

• Terminal ducts drain to larger and larger ducts, and eventually to the nipple

TDLU - site of origin of most cancers

Lobular Calcifications- form in acini -

Intraductal Calcifications- form in ducts -

Almost always benignSuspicious for malignancy

Due to calcified cellular

debris or secretions

Skin

Vascular

Coarse or “Popcorn”

Rim or “Eggshell”

Benign Calcifications

Fine Pleomorphic

“Variable in size, density and shape”

Suspicious Microcalcifications

“Thin, linear or curvilinear irregular”

Fine linear or branching

Suspicious Microcalcifications

Architectural Distortion

Architectural Distortion

• Normal architecture is distorted with no definite visible mass

• Look for abnormal straight lines or spiculations radiating from a point

• Differential diagnosis:

• Carcinoma vs scar tissue

Right - recurrence with IDC Left - IDC

Right - recurrence with IDC Left - IDC

Mass

Mass• A space occupying

3D lesion seen in two different projections

• 3 important descriptive terms:

• Shape

• Margin

• Density

•Benign features

• Round or oval

• Circumscribed

• Low density

•Suspicious features

• Irregular

• Microlobulated, indistinct, spiculated

• High density

Typically Benign

Typically Malignant

Asymmetries

Asymmetries• Unilateral deposits of

fibroglandular tissue with NO mirror-image correlate in the opposite breast

• A discrete mass is not seen on the initial MLO and CC views

• True pathology versus overlapping normal tissue?

Asymmetry

??

Rt MLO Lt MLO

Focal Asymmetry

Global Asymmetry

Objective 4

• Diagnostic work-up

“Work-up”

• Refers to additional testing required to determine the origin of an imaging or clinical abnormality

• Comprised of additional mammographic views, US, MRI and/or biopsy

Abnormal Mammogram

Additional mammographic views

? True abnormality

+/- Ultrasound

? Mass

+/- Biopsy

? Suspicious

• Straight lateral or 90 degree view

• Coned compression views

• Magnification views

• Pinched (Eklund) views

• Rolled view

• Extended CC view

• Cleavage view

• Tomosynthesis

Additional Mammographic Views

Magnification Views • Performed for better characterization of microcalcifications

• Focal spot = 1.6 times

• 2 views: CC and straight lateral (90 degree)

Magnification ViewLt MLO

Coned Compression Views

• Performed to differentiate normal overlapping parenchyma from a true abnormality

Coned Compression

Lesion does not persist on coned compression views in keeping with normal

fibroglandular tissue

Lesion persists on coned compression views in keeping with a true lesion

Coned Compression Views

Ultrasound confirms the presence of a mass suspicious for malignancy

Tomosynthesis

• - New technique created to produce a 3D picture of the breast using X-rays

• - Designed to reduce overlapping tissues in mammography

• - Results in high-resolution images at mammographic doses

Breast

Reconstructed planes

2D 3DTomosynthesis

Stationary breast

platform

X-ray tube swings during

tomo

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are needed to see this picture.

Tomosynthesis

• Ultrasound features of benign versus malignant lesions

Objective 5

Ultrasound

Benign vs Malignant Features

Simple Cyst

• Always benign

• Features:

• Anechoic (black)

• No wall

• “Through transmission”

Ultrasound Features of Solid Masses

Classic maligna

nt

Classic benign

Benign Breast Lesions

• Well circumscribed - doesn’t invade

• Wider than tall - obeys normal tissue planes

• Thin echogenic pseudocapsule - compresses adjacent tissue

• Gentle macrolobulations

• Intensely echogenic - contains fat

• Angular margins

• Spiculations

• Microlobulations

• Taller than wide

• Posterior shadowing

• Ductal extension/Branch pattern

• Microcalcifications

Malignant Breast Lesions

Margins: Angulated

Margins: Microlobulated

Ductal extension

Shadowing

Can we make the diagnosis of cancer based on ultrasound

features only?

Case 1: 83 yo, palpable mass medial left breast

Case 2: 88 yo, palpable mass UOQ left breast

Case 1: 83 yo, palpable mass medial left breast

Case 2: 88 yo, palpable mass UOQ left breast

Cancer Fibroadenoma

Invasive ductal carcinoma Involuted calcified

fibroadenomas

Always start with a MG in women 35

years old and greater!

• Breast Intervention

Objective 6

• Tissue diagnosis mandatory for diagnosis of breast cancer

• In the US, 1 million breast biopsies are performed annually to diagnose 200,000 breast cancers

• Avoids unnecessary benign surgical excisions and allows surgeons to plan appropriate surgery in the setting of cancer

• Extremely beneficial for patients and for the health care system in general

Breast Intervention

• How do we perform breast biopsies?

• Ultrasound guided biopsy

– Solid and complex solid-cystic masses

• Stereotactic biopsy

– Suspicious or indeterminate microcalcifications seen on MG

– Persisting suspicious asymmetries on MG with no sonographic correlate

• MRI guided biopsy

– Lesions identified only on MRI with no mammographic or sonographic correlate

Breast Intervention

Ultrasound Guided Biopsy

FNA(uncommon

) CNB VAD

Core Needle Biopsy

Fine needle aspiration

Vacuum-assistedDevice

Core Biopsy

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Vacuum Assisted Biopsy

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Stereotactic Guided Biopsy

Technique

• Scout image taken to locate lesion in biopsy window

• “Stereo Pair” obtained after moving x-ray tube +15° and −15° relative to 0° position

• X, Y and Z (depth) coordinates calculated by computer

Specimen radiograph confirms microcalcifications in the

specimen

Final diagnosis: DCIS

Pre biopsyPre biopsy

Post biopsyPost biopsy

Persisting focal asymmetry

Deploy marker clip at the site of biopsy

Preoperative Image Guided Localizations

• Pre-operative localization is used to ensure complete excision of nonpalpable breast lesions

• Localization device is inserted pre-operatively using mammographic or ultrasound guidance

• Helps guide the surgeon in the OR, improving clear margin and breast conservation rates

Preoperative Image Guided Localizations

MG or Ultrasound Guidance

46 yo - Multifocal Disease UOQ

2 wires inserted to guide surgical

excisions

Radioactive Seed Localization

• Low-dose I125 titanium prostate seed is placed at the target using mammographic or ultrasound guidance

• Surgeon uses radioactivity probe to localize, dissect and remove breast lesion

Image courtesy of The Mayo Clinic

Post-procedure mammogram

confirms accurate seed

placement adjacent to clip

X-ray of lumpectomy specimen to

confirm excision

• Role of MRI in breast imaging

Objective 7

• MRI has a high sensitivity

• Main roles include:

– High risk screening:

– BRCA 1 and 2 mutation carriers

– > 25% lifetime risk of developing breast cancer

– Radiation to anterior chest wall for treatment of lymphoma

– Local staging of breast cancer

– Assess response to chemotherapy

– Problem solving

Role of MRI in Breast Imaging

43 yo – BRCA1 carrier

Baseline Screening MRI

Bilateral breast cancer not seen mammographically

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Left breast

Clinical: • Upper outer quadrant • Palpable abnormality

MG: • Pleomorphic microcalcifications (BI-RADS 5)

Stereotactic Biopsy:

Final diagnosis: DCIS high grade

CC MLO

Local Staging with MRI

MRI: • Non mass enhancement (arrow) • Additional retroareolar mass (circle) for which US guided biopsy was performed

Mastectomy and SLNB wereboth performed

Final pathology: Invasive ductal carcinoma and ductal carcinoma in situ (DCIS)

(Total extent 8.0 cm)

2 min C+

2 min C+

2 min MIP

January 2012 July 2012

Post 6 cycles of chemotherapy

Assess response to chemotherapy with MRI

• Current recommendations for breast screening

Objective 8

– Who should have mammograms?

– At what age should screening be initiated?

Current Recommendations for Screening

Benefits of Screening Mammography

• - Reduction in breast cancer mortality by 40%

• - Lower rate of mastectomy, radiation therapy and axillary lymph node dissection

• - Less expensive treatment and less time off work

Limitations of Screening

Mammography...”Harms”• False Negatives

• 10-20% of breast cancers are only detected at breast self-exam or physical exam

• False Positives

• Only 5-40% of lesions are detected at screening and recommended for biopsy

• Over-diagnosis

• 11% of cancers found never progress

• Asymptomatic women 40-49 years - Annual screening MG

• Asymptomatic women 50-74 years - Every 1-2 years

• Women over 74 years - Every 1-2 years, if in good health

CAR Guidelines – Screening Mammography

When to Start Screening?

• - CTFOPH recommends screening women 50-74 and having a discussion about screening with women 40-49

• • - OBSP screens women 50-74

• - Canadian Association of Radiology, American Cancer Society, National Comprehensive Cancer Network, American College Radiology, College Obstetricians and Gynecologists, recommend screening women 40-74 +

Should I Screen after age 74?

• - For all ages, the mortality benefit from mammographic screening begins to be seen 5-7 years after the onset of screening

• - Mammographic screening can be continued as long as there is reasonable expectation of a life expectancy of at least seven years

• - Average life expectancy for an 80 year-old woman is 8.6 years which means that the healthiest quartile can be expected to live considerably longer

What is the Chance of Developing Cancer between 40-50 years old?

• - 1 in 69 women will be diagnosed with invasive breast cancer in their 40s

• - Breast cancer is the leading cause of cancer death in women < 50 years

• - There is a very low incidence of breast cancer below age 30

• There is no abrupt change at age 50

Annual U.S. breast cancer incidence rates

per 100,000 women as a function of age for invasive + in-situ

cancers

Numbers of Breast Cancers by Age

SEER, 2010, http://seer.cancer.gov/csr/1975_2007/

77% > 50 years

18% 40 - 49 years

• 5% < 40 yrs

• 18% 40-49 yrs

• 23% 50-59 yrs• 26% 60-69 yrs• 28% 70-79 yrs

No Role for Screening with

Ultrasound

• Average risk women - Screen with mammography

• High risk patients - Screen with mammography and MRI

• Screening versus Diagnostic mammography

• BI-RADS

• Review of mammographic abnormalities that warrant further work-up

• Diagnostic work-up

• Features of benign versus malignant lesions on ultrasound

• Breast Intervention

• Role of MRI in breast imaging

• Current recommendations for breast screening

Objectives

Thank you