Breast imaging

BREAST IMAGING

Dr. Sayan

Timeline of Breast Imaging• 1950’s – Breast Self Examination• 1960’s – BSE + Mammography• 1970’s – BSE + Mammography + Thermography + Ultrasound• 1980’s – BSE + Mammography + Better US• 1990’s – BSE + Mammo + US + MRI• 2000’s – Digital Mammo + US + MRI• 2020?? – Digital Mammo + US + MRI + MR spectroscopy +

Tomosynthesis + PEM + BSGI

1913 - Albert Salomon • Laid the foundations of mammography• 3000 mastectomy specimen • Collaboration of macroscopic anatomy with

microscopic examinations.1963 - 1966: Health Insurance Plan (HIP) of New York • First RCT- periodic screening with physical

examination & mammography. • 1/3rd reduction in mortality at 5 yrs f/u & sustained

benefit till 18 yrs of f/uIn 1965: 1st mammography unit the “Sénographe” was

built by Compagnie Générale de Radiologie” headed by Charles Gros

Mammography : History

• Mammography is a special type of X -ray imaging - to create detailed image of the breast.

• Permit earlier detection of abnormality

• High contrast resolution is required - attenuation diff. between normal & diseased breast tissue is so small

Mammography

X-ray tube

Compression device

Image detector

Film/Screen Mammography• Old method• The image is created directly on a film-

Non modifiable

• Less sensitive for women with dense breasts

• 10 - 20 % of breast cancers that are detected by physical examination are not visible on film mammography

• A major limitation of film mammography is the film itself – quality depends on exposure

Digital Mammography • Electronic (digitised) image of the

breast - stores it directly in a computer

• Can be manipulated

• Less radiation exposure than film mammography

• Improvement in image storage and transmission

• Cost 1.5 to 4 times more than film systems

Advantages of Digital Mammography

• Exposure can be tailored to enhance tissue contrast• Faster image acquisition• Shorter examination time• Improved contrast• Better delineation of parenchyma & subcutaneous tissue • Reproducibility• Electronic transmission ( Tele-mammography)• Less storage space

New advances• CAD- Computer Aided Detection• Dual energy subtraction• Contrast subtraction digital mammography

Digital Mammography

Basic positioning – CranioCaudal View• From above a

horizontally-compressed breast

• Will show as much as possible of glandular tissue surrounded by fatty tissue and the outermost edge of chest muscle

• Nipple will be shown in profile.

• Can't capture much of armpit and upper chest

Medio-Lateral Oblique view

• From the side and at an angle of a diagonally-compressed breast

• The angle allows more of breast tissue to be imaged including tissue in armpit.

• It will show glandular as well as fatty tissue

• Gives a larger area than a CC view

Other Views May be Taken for a Diagnostic Mammogram

• Latero-medial (LO) - from the outside towards the center

• Medio-lateral (ML) - from the center towards the outside

• Spot compression - compression on only a small area, to get more detail

• Cleavage view - both breast compressed, to see tissue near the center of the chest

• Magnification - to see borders of structures and calcifications

Why Use So Much Compression?• Holding breast away from chest wall permits projection of most tissue

& decreases noise from chest wall structure• less motion results in clearer edges (less blurring)• Decrease in dose due to reducing thickness thro’ which radiation has to

pass• Separates overlapping structure• Pressing close to detector minimizes geometric unsharpness• More uniform thickness and uniform exposure• Accurate registration of image for computer reconstruction algorithm

The compression force should be firm but should not cause pain; preferably should not be more than 20 N

Poulos et al. Breast compression in mammography: How much is enough? Australasian Radiology Volume 47, Issue 2, pages 121–126, June 2003

Mammography

SENSITIVITY 67% (60-78%)

SPECIFICITY 94% (93-96)

PPV 8.6 (3-16)

NPV 99.7% (99.6-99.9)

Sensitivity overall ≈ 67%, but lower in

• Young, dense breasts• Hormonal therapy• Mucinous, lobular pathologies• High grade or high proliferative indices• Short interval

Screening Mammography

in the average risk woman

Specificity overall ≈ 94%, but lower in

• Young, dense breasts, • Hormonal therapy• BIRADS not used• Prior breast surgery• BMI <25• No centralised screening/Quality Assurance programs• Long interval

Screening Mammography

in the average risk woman

Screening mammography Diagnostic mammographyFor asymptomatic ‘well’ women to detect unsuspected lesions

Scope For diagnosing breast changes or abnormalities that may have been detected through breast self exam (BSE) and/or clinical examination

Emphasis is on mass population screening to reduce overall mortality and morbidity

Emphasis Emphasis is on individual benefit

According to guideline followed

Target For women or men of any age who have symptoms or signs

Free service mostly as part of Govt. funded screening programme

Cost Medicare rebate may be available but out-of-pocket costs may be incurred

No referral required. Recommendations from health professionals are strongly encouraged

Referral Referral required from medical practitioner

Staff specialise in screening for and assessing impalpable lesions. Mammograms are read independently by two specially trained radiologists

Staff Staff experienced in a range of diagnostic procedures. Experience in breast cancer mainly with women presenting with palpable lesions/changes

Results letter notifying the woman screened and her primary health care providerWhere screening results are abnormal, notification is sent to the woman screened and her nominated general practitioner immediately

Notification Full report is sent to general practitioner or surgeon usually within a few days

17

Fibro-glandular Breast

• Dense with very little fat• Females 15-30 years of age

or 30 years or older without children

• Pregnant or lactating

18

Fibro-fatty Breast

• Average density• 50% fat & 50% fibro-

glandular• Women 30-50 years of

age or women with 3 or more children

19

Fatty Breast

• Minimal density• Women 50 and older

(postmenopausal), men and children

• Irregular/regular mass

• Ambiguous border

• Spiculated

• Heterogeneous density, mostly

higher than the Surrounding tissue

• Site: over 50% at upper-outer

quadrant

X-ray Findings of Breast Cancer• Calcification: clustered salt-like

microcalcification in 1/3 cases

inside/outside the mass, sometimes

only the microcalcifications

observed

• Architectural Distortion

• Retraction of nipple

• Thickening of skin

Spiculated/Stellate mass• central soft-tissue tumour mass

from the surface of which spicules extend into the surrounding breast tissue

• Approximately 95% of spiculate masses seen on mammography are due to invasive breast cancers

• typical ultrasound features are of an echo-poor mass, with poorly defined margins and posterior acoustic shadowing

Architectural Distortion• seen mammographically as

numerous straight lines usually measuring from I to

• 4 cm in length radiating toward a central area

TYPES OF CALCIFICATIONBENIGN MICROCALCIFICATIONS

• Smooth & round• Calcification with lucent

center • Dermal calcification• Vascular cal.• Large rod like cal.• Popcorn cal.

MALIGNANT MICROCALCIFICATIONS5 or more in numberEach equal to or less than 0.5mm in sizePleomorphic

Size Shape Density

Fine linear branchingDot and dash patternv, y pattern of calcification

Asymmetrical Soft Tissue Density• some carcinomas, particularly

small tumours• found in screening practice, may

not show typical features of• malignancy such as an irregular or

spiculate outline. These tumours• may appear on basic screening

films as asymmetricalsoft-tissue• opacities

Radiolucent Lesions• Oil Cysts - single or multiple, are

usually 2-3 cm in diameter, and result from trauma which is usually surgical

• Lipoma• Galactocele

BIRADS (Breast Imaging-Reporting And Data System)

Category 0- Need Additional Imaging Evaluation and/or Prior Mammograms For Comparison: (Incomplete Assessment)

• When no radiologist is there to report• Recall patient• Almost always used in a screening situation• Additional imaging evaluation - spot compression, magnification,

special mammographic views and ultrasound• If the study is not negative and does not contain a typically benign

finding, the current examination should be compared with previous studies. The radiologist should use judgment on how vigorously to attempt obtaining previous studies

BIRADSCategory 1: Negative

• The breasts are symmetric and no mass, architectural distortion, or suspicious calcification is present.

BIRADSCategory 2: Benign finding(s):

• Like Category 1, "normal" assessment, but the interpreter chooses to describe a benign finding

• Involuting/calcified fibroadenomas• Multiple secretory calcifications• Fat-containing lesions such as oil cysts, lipomas or Galactoceles• Hamartomas

• The interpreter may also choose to describe • Intramammary lymph nodes • vascular calcifications• implants or architectural distortion clearly related to prior surgery

Category 2 should be used when describing one or more specific benign mammographic findings which require no further evaluation

Category 1 should be used when no such findings are described

BIRADSCategory 3: Probably Benign Finding - Short Interval Follow-Up Suggested:

• Should have less than 2% risk of malignancy

• It is not expected to change over the follow-up interval, but the radiologist would prefer to establish its stability

• Three specific findings are described as being probably benign • Non-calcified mass• Focal asymmetry• Cluster of round (punctate) calcifications

BIRADSCategory 4: Suspicious Abnormality - Biopsy Should Be Considered:

• Do not have the classic appearance of malignancy • Probability of malignancy greater than those in Category 3. • Most recommendations of breast interventional procedures will be

placed within this category. • Relevant probabilities be indicated so the patient and her

physician can make an informed decision on the ultimate course of action

• 4A - Should be biopsied but has less chance of malignancy• 4B - Intermediate suspicion • 4C - Is of concern but does not have classic morphology of malignancy

Sanders et al. Clinical Implications of Subcategorizing BI-RADS 4 Breast Lesions associated with Microcalcification: A RadiologyâPathology Correlation Study". The ��Breast Journal 16 (1): 28–31 (2010)

BIRADSCategory 5: Highly Suggestive of Malignancy - Appropriate Action Should Be Taken:

• Lesions have a high probability ( 95%) of being cancer.

• This category contains lesions for which one-stage surgical treatment could be considered without preliminary biopsy.

• current oncological management may require percutaneous tissue sampling as,

• when sentinel node imaging is included in surgical treatment • neoadjuvant chemotherapy is administered at the outset.

BIRADSCategory 6: Known Biopsy - Proven Malignancy: Appropriate Action Should Be Taken

• Lesions identified on the imaging study with biopsy proof of malignancy prior to definitive therapy

• This category was added to the classification because sometimes patients are treated with neo-adjuvant chemotherapy.

Mammography Limitations• As many as 20% of breast cancers will be missed by mammography.

• Approximately 10% of women are recalled for additional workup and a significant portion prove to have no abnormality, resulting in unnecessary anxiety and cost.

• Tissue superimposition that is created by the overlap of normal breast structures in a two-dimensional mammographic projection can obscure a lesion making it more difficult to perceive or rendering it mammographically occult

Why Breast Tomosynthesis (3D mammography)?• Tissue superimposition hides

pathologies in 2D• Tissue superimposition mimics

pathologies in 2D

3D Improves Visibility by Reducing Tissue Superimposition

2D Mammogram Tomosynthesis

Better Sensitivity

2D Mammogram Tomosynthesis

Fewer Recalls

Digital Breast Tomosynthesis (DBT)L. Pescarini et al. Attualità in senologia; 2008

Digital breast tomosynthesis

3D Principle of Operation• X-ray tube moves in an arc

across the breast • A series of low dose

images are acquired from different angles

• Total dose approximately the same as one 2D mammogram

• Projection images are reconstructed into 1 mm slices

Compression PaddleCompressed Breast Detector Housing

Reconstructed Slices {

Arc of motion of x-ray tube, showing individual exposures

Tomosynthesis takes multiple angle Breast views and Reconstructs them into Cross-sectional slices

Screening mammograms and their radiation risks

Towards appropriate use of diagnostic imaging: A guide for medical practitioners and their patients. Cancer Council WA, 2011

• Two of the major factors affecting radiation dose are the amount of compression and the thickness and structure of the breast

• Studies have linked high doses of ionising radiation (>50mSv) to an increased risk of cancer. However, the risk is extremely low with the radiation dose received from a mammogram.

Breast UltrasoundDiagnostic test for evaluation of mammographic and palpable abnormalities

• Used as a 'second-look' procedure• Can differentiate cystic from solid mass• Characterize solid masses• Evaluate axilla for metastatic disease• First examination in young women <35 yrs and is valuable in the

assessment of mammographically `dense' breast• Being the only `real-time' imaging modality it can be used to

accurately localise or biopsy breast lesions

Indications• Symptomatic breast lumps in women <35 years• Breast lump developing during pregnancy or lactation• Assessment of mammographic abnormality (± further mammographic views)• Assessment of MRI detected lesions• Clinical breast mass with negative mammograms• Breast inflammation• The augmented breast (together with MRI)• Breast lump in a male (together with mammography)• Guidance of needle biopsy or localisation• Follow-up of breast cancer treated with adjuvant chemotherapy

Breast Ultrasound - procedure• 7.5-10 MHz linear array probe• patient is examined in the supine oblique

position• The side being examined is raised and the

arm placed above the head to ensure that the breast tissue is evenly distributed over the chest wall

Breast UltrasoundScreening ultrasound

• No radiation, no compression• 28% increase cancer detection when combined with mammography

compared to mammography alone • In the absence of any suspicious clinical lesion, a negative ultrasound and

mammographic examination has a very high negative predictive value

Not ready for widespread use• Low specificity, higher cost, lack of availability• Low sensitivity for calcifications of DCIS

Berg et al. Combined Screening With Ultrasound and Mammography vs Mammography Alone in Women at Elevated Risk of Breast Cancer. JAMA. 2008;299(18):2151-2163

Typical Ultrasound characteristics of solid breast

lesions

A typical 'tall' irregular spiculated hypoechoic attenuating mass s/o malignant breast tumour

1 2 3 4 2-4 overall0

20

40

60

80

100

mx us combined

Screening Study 11,130 patients, 221 patients w/cancer

Mammography 78%Mammography + Ultrasound 97%

Breast density is the most important factor in determining the sensitivity of mammography (higher density in pre-menopause and HRT)

Kolb et al Radiology 2002;225:165-175

Combined Mammography and Ultrasound

Breast MRI

Technical Requirements:

• High-field breast MRI (1.5T or >)• Gadolinium-DTPA injection• Dedicated bilateral breast coil• Good fat suppression techniques• High-resolution 3D gradient echopulse sequence

Breast MRI: Indications• Screening of High-Risk Women• Contralateral Breast Cancer in Newly Diagnosed Breast Cancer• Lobular Cancer• Occult Breast Cancer• Close or Positive Surgical Margins• Post-operative Scar vs. Tumor Recurrence• Neo-Adjuvant Chemotherapy• Implants and Known or Suspected Cancer• Problematic Mammogram

High Risk ScreeningAnnual Breast MRI and Mammography Screening is Recommended for Women Who Have: (Based on ACS Recomendations)

• BRCA1 or BRCA2 gene mutation • First degree relative with BRCA1 or BRCA2 gene mutation and have not

been tested themselves• Lifetime risk of breast cancer has been scored at 20-25% or greater,

based on one of several accepted risk assessment tools that look at family history and other factors

• Chest wall radiation between the ages of 10 and 30 yrs• Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-

Ruvalcaba syndrome, or may have one of these syndromes based on a history in a first-degree relative

Clinical IndicationsDetection of Contralateral Breast Cancer in Newly Diagnosed Breast

Cancer

• 10% of women with breast cancer will develop a new tumor in the opposite breast with a negative mammogram and physical exam at the initial time of diagnosis

• Finding cancers earlier may help women make treatment decision, potentially sparing additional surgery, radiation therapy and chemotherapy later

• Contralateral breast cancers more often identified when index cancer was infiltrating lobular carcinoma

AJR 2003, vol. 180:333-341NEJM 2007 vol. 356,No. 13:1295-1303

Clinical Indications

Infiltrating Lobular Carcinoma• Insidious cancer- Difficult to detect on mammography and physical

exam• Multifocal / multi-centric in up to 35% of cases and bilateral in 10%• Frequent cause of positive lumpectomy margins

Clinical Indications

Occult Breast Cancer• About 0.3% of breast cancers present with malignant axillary lymph

nodes, but normal breast examination and mammogram• Mastectomy standard treatment for occult malignancy• Up to 2/3 can be localized with MRI allowing breast conservation

surgery

Clinical Indications

Close or Positive Surgical Margins• Up to 50% of lumpectomies have inadequate margins, requiring

additional resection• MRI can locate residual or additional tumor foci• Applied pre-operatively, MR significantly decreases re-operations

Clinical IndicationsImplants and Known or Suspected Cancer• MRI is not affected by implants or silicone• Improves diagnostic confidence• Allows guided needle biopsy• Women with history of silicone injections can benefit from MRI

screening

Contrast Enhanced Breast MRI• Based on the fact that a

carcinoma is usually well vascularized. Thus a contrast medium will quickly accumulate in the tumor.

• The evaluation consists of finding suspicious regions in the images, calculating the absorption of contrast-medium in those regions, and deriving the diagnosis from that data

Without contrast

With contrast

Breast MRI• Breast cancers are usually irregular in shape and heterogeneous in

their enhancement on MRI• Both mammography and USG have limitations in the evaluation of the

chest wall. MRI is able to visualize the entirety of the chest wall. Enhancement of the pectoralis and intercostal muscles is indicative of chest wall invasion in patients with a posterior breast tumor

Baum F, Fischer U. Eur Radiol 2002

0 1 2

Morphology round, oval, lobulated linear, dendritic, stellate _

Margins well defined ill defined _

Pattern homogeneous inhomogeneous rim enhancement

Signal intensity low (<50%) moderate (50-100%) high (>100%)

Curve continuous plateau wash out

SCORE DIAGNOSTIC VALUE

0-1 Benign

2 Probably benign

3 Probably benign

4-5 Suspicious for malignancy

6-8 Highly suggestive for malignancy

Fischer scoreBREAST MRI

Benefits of Breast MRI• Can image breast implants and ruptures • Highly sensitive to small abnormalities • Used effectively in dense breasts • Can evaluate inverted nipples for evidence of cancer • May detect breast cancer recurrences and residual tumors after

lumpectomy• Can locate primary tumor in women whose cancer has spread to

axillary (armpit) lymph nodes• Can spot or characterize small abnormalities missed by

mammography • May be useful in screening women at high risk for breast cancer,

according to recent studies

Limitations of Breast MRI• MRI takes 30-60 minutes compared to 10-20 minutes for screening

mammography

• The cost of MRI is several times the cost of mammography

• MRI requires the use of a contrast agent

• MRI patients must tolerate any claustrophobia

• MRI can be non-specific; often cannot distinguish between cancerous and non-cancerous tumors

Sensitivity & SpecificityMammogram Vs Ultrasound Vs

MRI

Sensitivity Specificity

Mammogram 82% 99%

Ultrasound 86% 98%

MRI 3T 100% 94%

Haitham Elsamaloty et al . AJR 2009; 192:1142-1148, Increasing the accuracy of detection of Breast Cancer with 3-T MRI.

Sensitivity and Specificity of Annual MRI, Mammography, Ultrasound and 6

Monthly CBE in High Risk WomenAUTHOR MAMMOGRAPHY ULTRASOUND MRI CBE

SENSITIVITY (%)

SPECIFICITY (%)

SENSITIVITY (%)

SPECIFICITY (%)

SENSITIVITY (%)

SPECIFICITY (%)

SENSITIVITY (%)

SPECIFICITY (%)

Kuhl et al 33 98 33 80 100 95 NS NS

Tilanus-Linthorst et al

0 100 - - 100 95 NS NS

Stoutjesdijk et al

42 96 - - 100 89 NS NS

Podo et al 13 100 13 100 100 99 - -

Morris et al NS NS - - 69 77 - -

Kriege et al 40 95 - - 71 90 18 98

Warner et al 36 100 33 96 77 95 9 99

Cancer Imaging 2005; 5(1): 32-38

Ref: websites of various groups