Breast Imaging Techniques and Applications

Normal Breast

Terminal duct lobular unit (TDLU) = extralobular terminal duct (columnar cells, surrounding elastic tissue) + lobule. Lobule = intralobular duct (cuboidal cells, no surrounding elastic tissue) + ductules/acini + intralobular stroma. TDLU is the origin of DCIS, LCIS, infiltrating ductal/lobular carcinoma, fibroadenoma, most fibrocystic change, epithelial hyperplasia.

Segmental ducts -> lactiferous ducts -> lactiferous sinuses. Main ducts and branches are the origins of papilloma, papillary tumours, cause of duct ectasia.

Lobular stroma envelops the lobular acini, consisting of breast-specific hormonally responsive fibroblast-like cells mixed with scattered lymphocytes; source of fibroadenomas and phyllodes tumours. Interlobular stroma consists of dense fibrous connective tissue mixed with adipose; source of fat necrosis, lipoma, fibrous tumours, fibromatosis, sarcomas.

Sternalis (normal variant in 10%) runs along the sternum, superficial to pectoralis major, only seen on CC as a medial triangular density.

Physiological changes:

  • Premenarche – blind-ending ducts.
  • Menarche – development of ductules/acini.
  • Proliferation from increase in oestrogen/progesterone after ovulation -> epithelial proliferation, increase in number of ductules and lobules, oedematous intralobular stroma
  • Involution from fall in in oestrogen/progesterone after menstruation -> epithelial apoptosis, resorption of intralobular stroma. Mammography best performed just after menstruation (at involution phase), not done just before (proliferation phase).
  • Pregnancy -> marked epithelial proliferation and acini.
  • Prolactin, insulin, growth hormone -> secretory acini with intracellular vacuoles.
  • Perimenopausal – from 30s-40s proliferation decrease and atrophy of both lobules and connective tissue (fibroglandular regression), volume replaced with adipose.

Axillary/ectopic breast tissue is supernumary to main fibroglandular plate, persistence of mammary ridge. Aberrant/accesssory tissue may be anywhere along milk line (axilla->inguinal, forelimb->hindlimb buds), may have associated nipple/areola (polythelia).

Nodular densities are TDLUs (nonpregnant 1-8mm, but mostly 1-2mm). Linear densities are fibrous strands, vessels or milk ducts. Homogenous, structureless densities are fibrous tissue. Radiolucent areas are adipose tissue. Tabar mammographic parenchymal patterns:

  • Pattern I – Equal proportions of all 4 building blocks, most common premenopausal, changing to II or III with involution (HRT arrests or reverses this process). May have accessory breast tissue in axillary tail or lower half of breast, seen in retroglandular clear space on CC. Cancers may be hidden in areas of fibrosis, difficult to perceive if there are no calcifications, contour change or architectural distortion.
  • Pattern II – Mostly adipose.
  • Pattern III – Mostly adipose with prominent retroareolar ducts (retroareolar, periductal fibrosis or duct ectasia).
  • Pattern IV – Dominant nodular and linear densities, obscuring pathology (10% of women), resistant to involution. Adenosis is multiplication of acini and lobules in a disorderly manner (hyperplasia and hypertrophy) with TDLU’s now 3-7mm, later developing fibrosis usually centrally. Can grow more vigorously in a single area, palpable, histologically difficult to differentiate from carcinoma. Nodules are proliferating glandular structures, thick linear densities are increased periductal connective tissue.
  • Pattern V – Extensive homogeneous fibrous tissue, greatly obscuring pathology (5% of women), resistent to involution. Usually convex contour, homogeneous “ground-glass-like” structureless fibrosis; may be associated with normal parenchyma or hyperplasia.

Wolfe classification of distribution of fibroglandular tissue: N1 (most adipose with no ducts visible), P1 (ductal tissue <1/4 of breast), P2 (>1/4 of breast), DY (severe involvement with obscuration of normal ductal pattern).

Breast cancer prevalence low risk for patterns I-III and N1/P1, high risk groups IV-V and P2/DY; both increase with age, high risk group equivalent to low risk +15yrs.

All lymph from breast -> subareolar/Sappey plexus. Main path -> axillary nodes; accessory paths -> supraclavicular, contralateral axillary, internal mammary, subdiaphragmatic nodes and liver.

Poland syndrome – rare congenital unilateral underdeveloped/absent pectoralis muscle ± webbed fingers.

Involution

Involution causes scalloped contours of Cooper’s ligaments, evenly scattered TDLU’s, oval lucent areas giving a harmonic structure. Starts medial -> nipple -> UOQ -> central, any interruption or reversal of this order is suspicous.

  • Duct ectasia (mastitis obliterans) as periductal glandular tissue reduces. Dark/grey/yellow discharge. May have secretory calcs (rod/cigar/tubular).
  • Focal fibrosis (fibrous mastopathy) – hypoehoic with central ‘cloud-like’ echogenicity, heterogeneous. Predominantly premenopausal. Normal variant of involution or end result of inflammation.
  • Glandular islands (focal asymmetric glandular tissue) – asymmetric density, may ‘appear’ on HRT.

Mammography

kV 27-32 to create density of 1.6-1.8. A 4 film series is 1mGy. Higher risk in younger patients due to dense breasts (also reduces sensitivity), high radiosensitivity. Estimated risk is 2:million in age 40-49yo, 1:million 50-59yo. Standing position able to lean into unit easier than sitting. Recumbant imaging is difficult. Palpable lesions should be marked. Following mastectomy, mammo should be done yearly, including MLO of mastectomy side.

Views:

  • Mediolateral Oblique (MLO) – parallel to pec major (40-60 deg to horizontal) to image greatest amount of tissue. XRT and compression paddle superomedial. Pec major should be seen to level of posterior nipple line (line from nipple perpendicular to pec major). Nipple and inframammary fold profiled. Markers (side and view) near axillary tissue.
  • Craniocaudal (CC) – horizontal compression with XRT and paddle superior. Nipple and ideally pectoralis muscle seen centrally. Slightly lateral to midline to include axillary tail. Must see retromammary and anterior mammary (SC) fat.
  • True/90o lateral, mediolateral (ML), lateromedial (LM) – milk of calcium is gravity dependent, to further visualise lesion seen in only one view.
  • Spot/coned compression – for masses, determines whether lesion is real or summation shadow (requires two projections), better definition.
  • Magnification (M) – 1.8x for calcification, CC and true lateral.
  • Spot/coned compression with magnification (M) – 1.5 or 1.8x for masses and calcification
  • Exaggerated craniocaudal (XCC) – outer aspects and axillary tail.
  • Cleavage view (CV) – posteromedial breast.
  • Tangential (TAN) – verify skin lesions, palpable lesions obscured by dense tissue.
  • Rolled medial (RM) or lateral (RL) – verify true lesions, determine location. Sup breast rolled in said direction prior to compression on CC. Upper lesions move in rolled direction, lower lesions opposite.
  • Lateromedial oblique (LMO) – better superomedial visualisation, better visualisation and comfort for pectus excavatum, recent sternotomy or prominant pacemaker.
  • Implant displacement (ID) = Eklunds “push back” technique – implant pressed against chest wall and breast tissue pulled with greater compression.

Screening Mammography

Screening mammography is the only proven way to lower mortality from breast cancer, with greater than 24-29% reduction. Large (77,080 women) randomized controlled trial in Sweedin (1999) screening mammomography showed 30% reduction in breast cancer mortality (intention-to-treat analysis).

Positive predictive value for cancer specialist clinical examination 95%, mammo 95%, US 90%, FNA 99.8%. False negative mammograms in 9-16% (cancer not included on film, dense parenchyma, suboptimal technique, tumour type not visible, observer error); but generally detected at examination.

In NZ free BreastScreen Aotearoa mammography every 2yrs for 45-69yo; greatest benefit 50-59yo. Annual mammography if 1st degree relative (mother/sister) had premenopausal (<55yo) breast cancer, commencing 10yrs before their cancer onset. Other high risk patients include BRACA, previous atypia, previous breast CA, previous radiotherapy; should have annual mammography from 40yo. Screening can reduce mortality in 40-49yo, but some of these tumours have short preclinical detectable period (sojourn time) of 1-2y. Bienniel screening in 40-49yo fails to detect grade 3 cancers early, thus reducing short term mortality benefit; benefit largely limited to grade 2 ductal/invasive lobular/medullary cancers. Delayed and lesser benefit than women >50yo.

Impact of screening on mortality depends on histologic type. Detection of invasive lobular, medullary or grade 2 ductal greatly reduces mortality. Detection of DCIS, tubular, mucinous or grade 1 ductal cancers produces very little demonstratable effect on mortality in 10-15y. Interval cancers are typically more advanced at diagnosis, biologically more aggressive.

8% of pateitns are recalled for further study, biopsy in 1.6%, cancer in 0.6%. 50% cancers found are minimal (noninvasive or <10mm with negative nodes), >80% node-negative.

Whole breast US screening has lower PPV, with high biopsy rate. MR expensive and has high false positive, but may a have role in high risk groups.

Screening mammography MLO and CC views are compared to 2 studies prior (if available), and are double read. Screening is not diagnosis. If there is an abnormality further assessment is required with ultrasound ± further views.

Digital Mammography

Full-field digital mammography (FFDM) has higher contrast resolution, equal or better than DR, but lower spatial resolution. Dose is comparable in small breasts, lower in large. Faster image acquisition, ability for image processing, CAD, electronic storage, teleradiology. Trials have not shown increased cancer detection rates compared to film-screen.

Interpreting the Mammogram

CC and MLO viewed mirror-image at same time for asymmetric densities, architectural distortion, parenchymal contour changes, calcifications. All parenchyma is scanned with a viewer (eliminates extraneous light, focuses attention, magnifies). Masking horizontally (scanning caudal and cranial aspects) and oblique (caudal and cranial; parallel and antiparallel to pec respectively), by covering film with card/paper. Check diagnostic adequacy, then search for lesions, analyse lesions.

Forbidden areas where asymmetric densities are highly suspicious:

  • “Milky way” on MLO – 30-40mm region adjacent to pectoralis on MLO (peripheral UOQ).
  • Medial half of the breast on CC undergoes early involution, reducing likelihood of lesion being benign.
  • “No man’s land” on CC – retroglandular clear space. Densities here may represent parenchyma (accessory breast) or true lesion.
  • Retroareolar region difficult due to ductal and dense fibrous tissue, potential undercompression. Also undergoes involution just second after medial breast. Rich lymphatics here mean early tumour spread (hence worse prognosis).

Lesions are categorised into circuar/oval, stellate/spiculated, calcifications, thickened skin syndrome, or any combination of these.

Calcifications

Calcified secretory material or necrotic debris. Need to analyse distribution and form to identify type of cavity that they have been formed in (dilated ducts or lobules), and density of calcs to determine if malignant or benign. Mandatory microfocus magnification with or without spot compression in two projections. Benign calcification include clusters of apocrine cysts, sclerosing adenosis, fat necrosis or hyalinized fibroadenomas. 25-35% of calcifications undergoing biopsies are malignant. 7% of invasive carcinomas calcify, 22% of DCIS, 3% of LCIS.

Classified by distribution, form, size, density and less importantly number (number visualised greatly depends on technique).

Distribution: Widely scattered bilateral calcifications are usually benign (sclerosing adenosis, adenosis). Bilateral clusters with similar morphology are also generally benign.

  • Intraductal – linear, fragmented, branching. Usually malignant/high grade DCIS or plasma cell mastitis/secretory disease.
  • Intralobular/TDLUs – individual or multiple clusters of amorphous calcs in distended lobules. DDx difficult/impossible, includes fibrocystic change, grade 1 DCIS (mucin), grade 2 DCIS (necrosis), adenosis, sclerosing adenosis, tension cyst. Individual microcalcifications are distinguishable from each other. Histologically laminated onion-ring-like.
  • Miscellaneous/stromal – usually benign; in blood vessel walls, fibroadenomas, oil cysts, sebaceous glands, skin.

Form:

  • Casting, irregular, jagged (BI-RADS fine, linear, branching) – 96% are malignant, usually high grade DCIS with central luminal necrosis. Maximum width of calcification is limited by the lumen.
  • Crushed stone/coarse granular/broken needle tip/arrowhead/spearhead (BI-RADS pleomorphic, heterogeneous) – Irregular form, size and density. Clusters of calcifications from necrosis in luminal solid cell growth. 60% malignant (intermediate-low grade DCIS). DDx fibrocystic change (milk of calcium and involutional type calcification), fibroadenoma, partially calcified papilloma, fat necrosis.
  • Powderish/cotton ball-like (BI-RADS amorphous, indistinct) – Psammoma-body-like, unable to perceive individual calcifications. 50% low grade DCIS, others include sclerosing adenosis with or without atypia.
  • Indeterminate calcification (multiple cluster powdery, or clusters of varying size/shape/density) – mostly fibrocystic change, sclerosing adenosis, LCIS, but require biopsy to exclude occult DCIS or invasive carcinoma. If there is powdery calcification with coarse granular or tea cup-like calc, biopsy is indicated.
  • Other:
    • Calcification with lucent centre – benign, often in the sebaceous glands/skin, fat necrosis, oil cyst. Sebaceous gland calcification may be within glands (ring-like, hollow) or within a cavity (punctate), and often numerous.
    • Egg-shell-like calcifications
      • Radiolucent centre – calcified haematoma, oil cyst (from fat necrosis).
      • Oval/circular radiopaque centre – fibroadenoma (coarse egg-shell), cyst with calcified wall (thin egg-shell), capsule calcification around silicone implant. If small and retroalveolar, may represent intraductal/intracystic papilloma or intracystic carcinoma.
    • Milk of calcium – calcification in a cyst is a smudged cluster on CC and dependent curvilinear/linear on true lat.
    • Arterial calcification – tubular parallel lines, associated with tubular soft tissue.
    • Coarse, “pop corn-like”/irregular calcification – fibroadenoma (myxoid degeneration). No DDx
    • Rod-like/”cigar”-shaped – Secretory disease/plasma cell mastitis being smooth, long, thick linear radiating to nipple, usually bilateral in ectatic ducts, more lucent centrally. From inspipasated secretions in dilated ducts.
    • LN – coarse calcification from granulomatous disease; microcalcifications in metastatic breast cancer or ovarian cancer. Gold deposits from RA treatment may be seen.
    • Others include calcified sutures (curvilinear), cavernous haemangioma (small calcifications that vary in form and size or larger bizzare calcs), calcification in postsurgical scar (dystrophic/heterotropic, lava-shaped), warts (rarely calcify, but if do are deceptive). Tattoo sign – skin calcifications the retain relative position with each other on multiple views.

Density is evaluated by intraparticulate and interparticulate analysis. Granular and casting calcifications are of varying density. Malignant calcifications are generally numerous <0.5 mm (microcalcifications), greater in number more likely malignant.

Mammographically suspicious calcifications may be within non-neoplastic tissue, but adjacent tissue may show occult low grade DCIS or LCIS.

Density

Densities are seen on one view, masses on at least two views. True masses have convex borders (cf concave fibroglandular tissue) are more dense centrally, distort architecture, on multiple projections including spot compression (to check for summation and margins). All new solid masses at Christchurch are biopsied/FNA; except multiple bilateral benign lesions, typical FA popcorn calcification, or if it contains fat.

Assymetric densities can be clarified with coned-down compression views to spread out tissue, usually without magnification:

  • Composite/summation shadow (pseudostellate) – from overlapping tissue only seen on one view, disappear with focal compression.
  • Normal parenchyma or focal fibrosis – 3% of women have areas of asymmetry but are histologically normal, fat is seen interspersed with denser tissue on spot compression. If corresponds to suspicous palpation biopsy is recommended. Includes accessory breast tissue, asymmetric involution, hormone effect (premenopausal, exogeneous oestrogen), fibrosis/scar tissue (posttraumatic/postinflammatory). Densities are nodular (normal TDLU 1-2mm, adenosis 3-9mm), linear (ducts), fibrosis (structureless “ground glass-like” with concave contours, slight architectural distortion), or adipose with scalloped contours.
  • Nonspecific asymmetric density (NSD) – De novo fibrosis with architectural distortion, possible malignancy (low grade DCIS “fire” with surrounding fibrosis/desmoplastic reaction “smoke”). Biopsy, especially if architectural distortion is present or emphasized with CDC.

Stellate/spiculated lesions. 93% are malignant (invasive ductal, lobular, tubular). Small carcinomas may have imperceptible central mass, but spiculating lace-like fine reticular structures causing distortion/assymetry. Benign lesions include radial scar, fat necrosis, granular cell myoblastoma. Absence of previous trauma/surgery excludes fat necrosis.

  • Tumour centre – either distinct mass or oval/circular radiolucent areas. Best assesed with spot compression.
  • Radiating structure/spicules:
    • “White star” – sharp, dense fine lines of variable length in all directions. The larger the central mass, the longer the spicules (dense collagen). Usually invasive ductal/tubular carcinoma.
    • “Black star” – very fine, linear or curvilinear/drooping, bunched like broom or sheaf of wheat, lower density. The longest spicules are thin, closer, more numerous and clumped in thick aggregates. Spicules are dilated proliferating ducts. Includes radial scar, fat necrosis, invasive lobular (usually straighter, dense spicules, but may lack central solid mass).
  • Localised skin thickening or retraction, esp superficial lesions. Present in invasive carcinoma, traumatic fat necrosis (esp post-op). Never present in radial scar.

Circular/oval lesions. Only 5% of well-defined/circumscribed lesions are carcinomas (infiltrating ductal, papillary, mucinous, medullary)

  • Contour:
    • Sharp/well-defined border – Halo sign/mach band (narrow radiolucent ring or segment) if extensive is usually a tension cyst, if short/partial usually fibroadenoma. Capsule (thin curved radiopaque line) when contains fat or oil around fatty lesions. Usually benign (cyst, fibroadenoma, papilloma) except rare intracystic/papillary/medullary/mucinous carcinoma, sarcoma, or carcinoma in fibroadenoma.
    • Unsharp/ill-defined border or comet tail – raises suspicion of malignancy. Invasive ductal carcinoma, less often invasive with special features, occasionally benign lesion.
  • Density (compared with parenchyma, or nipple in the case of involution):
    • Radiolucent (benign) – lipoma, oil cyst, galactocoele.
    • Combined radiolucent/radiopaque (benign) – fibroadenolipoma/hamartoma (large), galactocoele (nursing), intramammary LN (typically upper outer posterior 3/4 with fatty centre or lucent notch representing fattty hilum), haematoma (trauma).
    • Low density radiopaque/isodense – fibroadenoma (young, nontender), cyst (perimenopausal, pain with pressure). Rarely sebaceous cyst, cavernous haemangioma, papilloma, wart, abscess, cystosarcoma phylloides, papillary/mucinous carcinoma.
    • High density radiopaque – carcinoma, sarcoma, mets, cystosarcoma phylloides, haemorrhagic cyst, abscess, haematoma, lymphadenopathy, sebaceous cyst
  • Form, orientation – Cysts are usually orientated along direction of nipple/trabecular structures, whereas solid tumours are randomly orientated.
  • Size – very large (>50mm), intermediate (~30-50mm) or small (<30mm). If <3-5mm US is usually not helpful.

Intramammary LN are reniform with fatty hilum/notch, <10mm, usually UOQ, hypoechoic. Axillary lymph nodes normally <20 mm with lucent centres or notches. In lymphadenopathy nodes are homogeneously dense and enlarged, from breast carcinoma, mets, lymphoma, leukemia, AIDS, RA, SLE, scleroderma, psoriasis, eczema.

Skin lesions may have air trapping at edges or interstices. Tangential view or repeat film with skin markers can confirm.

Multiple masses are usually cysts, fibroadenomas or multiple papillomas; metastases usually unifocal.

Trabecular thickening – thick streaky lines from lobular or ductal carcinoma.

Thickened Skin Syndrome

Skin >2mm thick. On examination breast is larger and heavier, shows peau d’orange, axillary lymphadenopathy. Unilateral skin thickening can be from inflammatory carcinoma (cell obstructs dermal vasculature), radiation (1st 6/12, resolving over years), diffuse mastitis, lymphatic or venous obstruction (from metastases, surgery, thrombosis). Bilateral skin thickening can be casued by anasarca from CHF, renal failure, cirrhosis or hypoalbuniemia; but assymetry can occur.

On mammography skin is thickend moreso dependently, has increased overall density, increased reticular pattern (fibrous strands from proteninaceous lymphatic fluid stagnating in interstitial spaces and dilated lymph vessels). Compare density of markers, as newer mammography machines auto-expose, falsely equalising breast density.

Lymphoedema arises from:

  • Axillary LN obstruction – breast cancer metastases, primary lymphatic enlargement, gynaecological malignancy blocking lesser pelvis lymphatics (overload of axillary and supraclavicular lymph via thoracohypogastric collaterals), mediastinal LN obstruction (bronchial/oesophageal cancer).
  • Lymphatic spread to contralateral breast, blocking intradermal or intramammary nodes.
  • Inflammation esp retromammary abscess.
  • Right ventricular failure, CRF, anasarca (extreme generalised oedema from CHF, liver failure, renal failure, protein deficiency, IVF). Can be worse on one side if lying on that side.
  • Radiation – max at 6/12, usually improving/resolving by 1-3 years.

Architectural Distortion

From fat necrosis (trauma, surgery), radial scar (with interspersed fat), carcinoma. DDx involutional change. Normal parenchyma has scalloped contours; straight lines are suspicous. Biopsy required. Parenchymal contour change may be the only sign of a small invasive tumour, with indrawing or tent sign. Edge sign – focal change in margin of glandular tisue with straightening or angulation with ‘pulling in’. Contraction of breast may be part of desmoplastic reaction and be only sign of malignancy.

Ultrasound of the Breast

Linear array 10MHz. Differentiates solid from cystic lesions. Unable to further evaluate solid/complex lesions. 1st line imaging for <30yo. Performed before further mammography views if screening mammography shows well-defined round/oval lesion. Boundary echoes (halo) represents desmoplastic reaction/invasive margin around a nidus. Shadowing is seen in 70-80% of carcinomas, ~100% of scirrhous lesions. Downstream duct dilatation suggests ductal invasion; upstream dilatation suggests obstruction.

Breast MRI

Indicated for evaluating breast implant integrity, local extent of invasive breast cancer (esp lobular carcinomas), multifocal/multicentric tumours, residual disease posterior lumpectomy or radiation, evaluating axillary metastases with no known primary, screening in those with BRACA. Prone axial and sagittal planes with T1W (differentiate glandular from fatty tissue), T2W and FS pre, posterior and delayed for kinetic enhancement curves. Benign lesions have smooth margins, nonenhancing internal septations, bright T1 (complicated/haemorrhagic cyst, fat necrosis, LN fatty hilum), minimal/no or diffuse patchy enhancement. Malignant lesions are spiculated/irregular; peripheral/rim, regional or ductal enhancement. Most invasive carcinomas have low T2, apart from medullary or mucinous which are high (similar to cysts).

Kinetic curves have fast, medium or slow early contrast phase; and persistent, plateau or washout intermediate/late phase. Most invasive carcinomas have rapid enhancement with plateau or washout, but DCIS, invasive lobular, tubular and mucinous carcinomas may have slow enhancement. Not reliable for DCIS. Benign lesions have persistent enhancement after 2min.

Ductography/Galactography

To investigate cause of spontaneous nipple discharge, usually papillomas or less likely carcinomas; utility controversial. Contrast injected into duct via 30G blunt needle and subsequent films taken to find intraductal tumour. 0.2-0.4mL water soluble contrast. For bloody discharge, surgeon may inject methylene blue before dissection along it, instead of ductography.

Pneumocystogram

Cyst aspirated then filled with air. Mammography to check for presence of intracystic tumour.

Triple-Test Principle

Involves physical examination, imaging (mammo, US, MRI) and biopsy (FNA, core). If imaging and pathologic diagnoses are disconcordant, repeat core biopsy or excisional biopsy should be done.

Fine-Needle Aspiration Biopsy (FNAB)

Compromises subsequent mammography. Used to confirm malignancy, not exclude. 21G or small needle using syringe or without (syphon method).

Core Biopsy

Superior to FNA due to cytology requiring specially-trained pathologist (core biopsy evaluated by any pathologist), amount of tissue usually sufficient for diagnosis. Cannot exclude areas of invasion or microinvasion.

Guided by stereotaxis, US or MR. Using 14-gauge biopsy gun (spring-action inner cannula with tissue notch then outer cutting canula) or 9-11-gauge vacuum-assested needle (sucks tissue into specimen notch before outer cutting cannular fired). Vacuum assisted device allows multiple specimens per needle pass and improved sampling of microcalcifications. Smaller 16 or 18 guage can be used to reduce risks, penetrates lesions easier (especially mobile fibroadenoma). Excisional biopsy should be performed in any atypical ductal or lobular hyperplasia (10-48% of these are carcinoma). Marking clips can be placed after biopsy if features may not be present on subsequent imaging (eg cyst after aspiration, only a few microcalcifications present).

Stereotactic units can be added to standard mammography units (must be seated or decubitus position, limited working space), or dedicated prone unit (minimised movement and vasovagal reactions). After scout view, negative and positive 15o images obtained and calculations made to determine depth. LA, small skin cut, biopsy needle inserted into guide before confirmation views and biopsies. Can be performed for calcifications or masses. Nottingham criteria for adequate sample is at least 5 calcifications total, or calcifications in at least 3 cores (out of 5).

Localisation/fenestrated plate with grid can be used for biopsy or surgical localisation.

US biopsies given LA then biopsy parallel to chest wall, preferably radially (to cross less number of radially-arranged tough Cooper’s ligaments). Pre- and post-fire images saved.

MR biopsy only performed with lesions only seen on MR. Requires MR-compatible vacuum assisted biopsy device after localisation from the MR grid system. Marking clip can be placed to use as targed for stereotactic biopsy if needed.

Cysts can be aspirated via US with 22-guage needle before biopsy. Vacuum-assisted devices are preferable as only one needle pass is required, and it is likely fluid surrounding the lesion will leak into surrounding tissue thus making visualisation difficult for further passes.

Localisation of Occult Breast Lesions for Surgery

Wire or blue dye localisation. Hookwire localisation involves insertion of a needle directly superficial to the lesion after a view is taken with subsequent check. Further view at 90o taken to determine depth and later check view with optimal position of hookwire 10-20mm beyond lesion. Wire inserted through needle and needle withdrawn. Ultrasound is performed to mark on skin location of the wire. For dyes (methylene blue), optimal position is within or a few mm beyond the lesion; not often used as diffusion can occur resulting in larger than necessary excision, and also interferes with oestrogen receptor analysis. Bracketed localisations recommended for nonpalpable lesions >20mm, with more than one wire used to demarcate extent of the lesion, thus promoting complete removal. Excised tissue should be radiographed to ensure all abnormality is removed (failure in 1-5%). Localisation usually performed under mammography, but can also be done under US or MR guidance.

Management of Breast Pain

If >35yo mammography and USS. If <35yo USS only. Low rate of positive imaging. Surgical review.

Breast Imaging – Reporting and Data System (BI-RADS)

American College of Radiology standardized report for Mammos, breast US and MR.

  • Description of breast composition/density (thus sensitivity) with either entirely fat (<25% glandular), 25-50%, 50-75% or extremely dense >75% glandular tissue.
  • Side and position of findings on clockface and zone
  • Description of findings including comparison to previous.
  • Assessment category:
    • BIRADS 0 – Incomplete. Further imaging required.
    • BIRADS 1 – Negative, no lesion seen. Return for routine screening.
    • BIRADS 2 – Benign, characteristic benign lesion or proven on biopsy. Return for routine screening.
    • BIRADS 3 – Probably benign, eg circumscribed mass, benign appearing calcs or asymmetric density not palpable. Risk of malignancy <2%. Initial short-interval followup (6/12 on affected breast, further 6/12 bilateral, yearly for 3yrs).
    • BIRADS 4 – Indeterminate/suspicious. Subdivided into 4A (low suspicion) or 4B (high suspicion). Biopsy suggested.
    • BIRADS 5 – Probably (~95% probability) malignant. Biopsy recommended.
    • BIRADS 6 – Biopsy proven malignancy.

Classification of disaese:

  • A round/oval – A1 cystic: A1a no intracystic growth, A1b intracystic growth (biopsy may be required. A2 solid: A2a clinically or mammographically malignant, A2b benign.
  • B stellate – B1 white star, B2 black star.
  • C micocalcifications – C1 casting type, C2 broken needle, C3 indeterminate.