Standards of the Polish Ultrasound Society - update. Sonomammography examination.

The use of BIRADS classification has been recommended in sonomammography examinations in Poland since the year 2010. It was developed by the Polish Ultrasound Society and published in Ultrasound Examinations Standards of the Polish Ultrasound Society. Standards, based on BIRADS-usg classification, introduced uniformity in breast ultrasound examination descriptions and in the terminology of pathological lesions in breasts. BIRADS-usg classification takes into account breast morphological structure elements and pathological focal lesions in them. It enables the distinction between benign lesions and lesions suspected of being malignant. It contains information on the malignancy risk of focal lesions and proposals of diagnostic-therapeutic algorithms (including biopsy) in relation to lesions of different character. The Polish Ultrasound Society recommends performing prophylactic sonomammography examinations every 12 months in women over the age of 30 because of the increasing breast cancer morbidity in women from all age groups. In this article a spectrum of focal changes in breasts are presented within the relevant BIRADS-usg classification categories. The features of ultrasound morphology, enabling them to be classified to particular categories of BIRADS-usg classification are discussed. Management algorithms which may help clinicians to diagnose breast cancer and to treat it are proposed. Elements of medical history, physical examination, recommended techniques of sonomammography examination performance, technical parameters of ultrasound machine and examination description standards are presented. This article was prepared based on the Ultrasound Examination Standards of the Polish Ultrasound Society which was published in 2011 and updated. It contains numerous pictures visualizing BIRADS-usg classification.

Introduction

In 2007 in the pages of “Ultrasonografia” (currently “Journal of Ultrasonography”) the Polish Ultrasound Society (PUS) for the first time in Poland presented BIRADS-usg classification in ultrasound breast examination (sonomammography)(. It was introduced for ultrasound examination descriptions in 2010 based on standards developed by the Team of Experts of PUS in 2008 Ultrasound Examinations Standards of the Polish Ultrasound Society which was then introduced in 2011(.

Because of the increasing breast cancer morbidity in women from all age groups, including patients under 50, PUS recommends performance of prophylactic sonomammography examinations every 12 months in women starting from 30 years of age. These examinations, performed regularly every 12 months starting from 25 years of age, are also recommended by the Polish Union of Oncology as complementary in relation to mammography (MMG) and magnetic resonance mammography (MMG-MR) which in women from high and very high breast cancer morbidity risk should be performed every 6 months alternately (Diagnostic-therapeutic Management Recommendations in Malignant Neoplasms – 2011)(.

In 1993 the American College of Radiology (ACR) in cooperation with many organizations, inter alia the Food and Drug Administration, the American College of Surgeons, the College of American Pathologists and the National Cancer Institute, worked out BIRADS classification (), primarily for MMG examinations descriptions. Further updates came out in 1995, 1998 and 2003. The last, fourth edition, apart from MMG examination standardization, also contains recommendations and guidelines for BIRADS classification use in ultrasound and in MMG-MR.

BIRADS classification introduced standardization of breast imaging examination descriptions and the terminology of pathological lesions in breasts. It takes into account breast morphological structure elements and ultrasound focal lesions significant in the differentiation of their character. It gives the percentage of focal lesion malignancy risk. Moreover, it contains diagnostic-therapeutic algorithms (including biopsy) in relation to lesions of different character.

Medical history and breast physical examination

Breast US examination is performed at each stage of breast disease diagnostics – from prophylactics to clinical lesions diagnosis (palpable, visible in other imaging examinations) or subclinical, and also for biopsy monitoring. It should be preceded by taking medical history and physical examination and the analysis of the breast imaging and microscopic examinations performed so far. From medical history the doctor should obtain information about: the age of the patient, breast imaging examinations performed (US, MMG or MMG-MR), date of last menstrual period, number of births, breast feeding (including its duration), the use of hormonal treatment (contraception or hormone replacement therapy), the incidence of neoplastic diseases of breast and/or ovaries in the family, the presence and type of nipple discharge, breast traumas undergone, surgical treatment, chemo- or radiotherapy.

During physical examination breast palpation should be done (bearing in mind radial arrangement of glandular lobes around areola and nipple) as well as palpation of axillary fossa and supra- and infraclavicular fossa. The examination should be performed with fingers adducted, leading the hand radially along each lobe, from the breast perimeter towards the nipple. The patient should be examined in a standing and supine position, with her arm hanging next to the body and then behind the head. Finally, the nipple should be squeezed with two fingers to check for any provoked discharge.

One should pay attention at the shape, symmetry, size of breasts, skin, nipple and areolas pigmentation, unevenness and skin and nipple dimpling, presence of edema, scars and lacunas. In cases where thickening or nodules are found one should assess their size, susceptibility to compression, mobility in relation to skin, surrounding tissues and thoracic cavity wall.

It is essential to perform the examination in a properly heated room in order to avoid skin and nipple contraction.

US machine

According to PUS standards the US machines for the performance of sonomammography examinations should fulfill the following technical criteria:

128 transmitting-receiving channels minimum;

high frequency linear transducer, electronic, broadband, in the frequency range of 5.0–10.0 (if possible – 12.0–14.0) MHz;

transducer front length not shorter than 40 mm;

second harmonic option;

color Doppler and power Doppler;

programs for the calculation of length, area, volume;

apparatus with extended field of view is recommended;

apparatus equipped with elastography option is recommended.

The use of long front transducers (60–80 mm) facilitates and accelerates the examination, enabling the whole glandular lobes to be obtained in one image with no necessity for transducer translocation. For the examination of small breasts, skin and superficial lesions it is recommended to use a standoff pad or great amount of gel.

Examination technique

The method of the transducer leading is determined by anatomical breast structure, that is the radial arrangement of glandular lobes around the areola and nipple. The examination should be performed using radial technique, making longitudinal sections. During examination one may perform a controlled compression of the breast tissues with the use of the transducer which is useful for the assessment of the post-nipple and postareolar area, the content of lactiferous ducts and the assessment of deformability of visualized focal lesions. The change of breast position during examination is also a valuable maneuver, particularly in the assessment of fluid level translocation in fluid-filled lesions which does not translocate under the compression of the transducer. Each pathological lesion in breasts should be visualized in at least two perpendicular sections and assessed qualitatively in color Doppler and power Doppler examinations with regard to its vascularization pattern. Second harmonic option facilitates the assessment of focal lesions morphology, their boundary and lactiferous ducts contents. In sonoelastography the assessment of lesion displacement is possible taking into account the differentiation of focal lesions character in breasts.

Characteristics of breast lesions

Breast US examination enables the visualization of particular anatomical elements of the breast (with distinction into the following zones: preglandular, glandular, post-glandular), such as: skin, lactiferous ducts, terminal duct lobular units (TDLU), fat tissue, major and minor pectoral muscle, lymph nodes of breast lymph drainage.

Pathological lesions visible in sonomammography are:

pathological lesions of breast skin: edema, thickening, inflammation (thickening >3 mm, increased echogenicity, increased vascularization), indentation, focal solid lesions, fluid filled lesions, scars and Cooper ligaments pathologies (e.g. thickening or extension);

expanded lactiferous ducts with the assessment of their contents (fluid, tissue structures) and localization;

focal solid and fluid filled lesions;

fluid lesions, that is simple cysts, cysts with dense contents, with tissue proliferation, abscesses, hematomas, other fluid reservoirs;

inflammatory lesions causing glandular tissue architecture disorder.

Visualized focal lesions in sonomammography examination should be assessed analyzing in sequence their ultrasound features, according to the terminology proposed in Ultrasound Examinations Standards of the Polish Ultrasound Society ( and in ACR BI-RADS®– US Lexicon Classification Form (2003)(.

The following aspects are subjected to analysis:

focal lesion echogenicity in relation to adipose tissue (isoechogenic, hypoechogenic, hyperechogenic, mixed or anechoic lesion);

shape of focal lesion (oval, circular or irregular);

lesion margin (well-circumscribed or not, including spiculated, angular, microlobular or indistinct);

lesion boundary (abrupt interface or not with echogenic halo – fibrous reaction);

lesion orientation (prevalence of superior-inferior dimension over lateral-lateral dimension or inversely);

echogenicity of tissues behind lesion (enhancement of US beam, acoustic shadow or both phenomena);

lesion vascularization (within it or in surrounding tissues);

calcification within the lesion (micro <0.5 mm or macro ≥0.5 mm);

displacement (elasticity) of the lesion (undergoing large, medium, minimal displacement or not);

lymph nodes – intramammary, axillary: thickened hypoechogenic cortical zone or its focal bulge, round shape, uncircuscribed capsule, atrophy or dislocation of the core zone/hilum and pathological vascularization pattern(.

Lesion classification for BIRADS category

Classification into particular BIRADS-usg categories takes the following elements into account:

medical history outcome;

analysis of imaging breast examinations performed so far;

the result of the physical examination, including the assessment of skin pathologies such as: blushing, redness, orange peel look, nipple or skin dimpling, uneven outline of the nipple, ulceration or palpable lesions with the division into palpable lesion (tumor or thickening), its mobility, elasticity, soreness, presence of nipple discharge with the division into small risk group (bilateral, from many ducts, milky or greenish, non-spontaneous) and high risk (from the ostium of a single duct, unilateral, bloody or serous, idiopathic);

sonomammography examination result.

According to PUS Standards, BIRADS-usg contains 6 categories: 1–6. Category 0 has not been taken into account. In American classification ACR BI-RADS® – US from 2003 category 0 is given in case of difficulties in the differentiation in US examination between scar and recurrence in patients treated because of breast cancer and in women whose US examination had been performed before screening or diagnostic MMG(.

In MMG descriptions, mainly screening, BIRADS 0 category indicates incomplete assessment, particularly in changes demanding further verification based on additional imaging examinations and/or comparison with previous examinations.

PUS standards distinguish 6 BIRADS-usg categories.

BIRADS-usg 1 category includes normal breast images, including:

adolescent breast in all stages of development and maturation;

breast of glandular structure, glandular-fatty structure, fatty-glandular structure in volumetric equality between fatty tissue and glandular tissue, breasts during pregnancy, lactation, hormonal treatment;

breasts with fatty and fibrous remodeling and stromal fibrosis;

normal lactiferous ducts with anatomical-physiological units TDLU;

normal male breasts.

Fig. 1 presents the algorithm of lesions belonging to BIRADS-usg 1 category.

Fig. 1

Management algorithm for BIRADS-usg 1 and 2 category lesions

Figs. 2–4 presents example ultrasound images of this category.

Fig. 2

Glandular structure breasts. Normal terminal duct lobular units (TDLU) image

Fig. 4

Breasts during lactation. Dilated lactiferous ducts in glandular tissue image (arrows)

Adipose structure breasts. Normal fat granules image

BIRADS-usg 2 category contains lesions unequivocally benign, including:

solid, fluid filled or solid-fluid filled;

well-distinguished, hypoechogenic, hyperechogenic or of mixed echogenicity, oval or spherical, with prevalence of lateral-lateral dimension over superior-inferior dimension.

Such lesions do not demand performing further imaging examinations. Control examination should be performed normally after 12 months(.

BIRADS-usg 2 category includes inter alia:

single and multiple simple cysts;

cysts with thin-walled septa, of polycystic outline;

cysts with dense contents, galactoceles, lipid cyst, cyst with calcifications in the walls and fluid levels;

dilated ducts with dense or normal (not dense) contents, of even wall outlines, with no parietal structures;

inflammatory lesions of breast, skin and abscess;

post-traumatic pathologies of breast, hematomas, scars after surgical procedures, breast implants;

post-radiation alterations;

fibrocystic mammary dysplasia;

gynecomastia, steatomastia;

calcification (macro) in gland and in focal lesions;

intramammary lymph nodes of preserved normal structure;

fibroadenomas with macrocalcifications not enlarging during observation, cytologically verified;

lipomas, hemangiomas;

Mondor's disease (that is superficial thrombophlebitis of breast veins).

Fig. 1 presents the algorithm of lesions belonging to BIRADS-usg 2 category.

Figs. 5–7 present examples of focal lesions classified to BIRADS-usg 2 category.

Fig. 5

Single simple cyst image (well-defined edges, echoless center, thin capsule on the whole circumference, enhancement behind the lesion, edge shadowing)

Fig. 7

Dilated lactiferous ducts with dense contents image

Single cyst with thin-walled septa image (arrows)

BIRADS-usg 3 category includes lesions probably benign, of malignancy risk less than 2%. Depending on the family history, age and patients’ choice, a control US examination in 6 months or biopsy are recommended. In sonomammography BIRADS-usg 3 lesions are:

solid, well-defined;

oval, with prevalence of lateral-lateral dimension over superior-inferior;

hypoechogenic;

often with enhancement behind the lesion;

with no pathological lymph nodes in ultrasound examination of the area of breast lymph drainage.

An assessment in sonoelastography is useful in making the decision about cytological verification. The indication of large displacement of the lesion should suggest the performance of a control examination in 6 months(.

BIRADS-usg 3 category includes inter alia:

cysts with dense contents, insusceptible to compression, with thick walls and polycystic outline;

cysts with fluid levels which do not translocate while changing breast position during examination;

conglomerates of fine cysts;

dilated lactiferous ducts with dense contents, with no parietal structures, with even margin, insusceptible to compression;

single and multiple fibroadenomas;

hamartomas.

Algorithm of BIRADS-usg 3 lesion is shown in fig. 8.

Fig. 8

Management algorithm for BIRADS-usg 3 category lesions

Figs. 9–11 present examples of focal lesions classified to BIRADS-usg 3 category.

Fig. 9

Cyst with thick walls of polycystic shape image

Fig. 11

Fibroadenoma image (solid, hypoechogenic, oval lesion, of circumscribed margin with prevalence of lateral-lateral dimension over superior-inferior dimension)

Fine cysts conglomerate image

BIRADS-usg 4 category includes suspected lesions which do not show in ultrasound image features of classical malignant neoplastic lesion, but the range of probability of malignancy of the lesion of this category equals from 2% to 90%(. These lesions:

do not fulfill BIRADS-usg 3 category criteria;

are focal solid or solid-fluid filled, hypoechogenic;

with superior-inferior dimensions greater than lateral-lateral;

have irregular shape and/or uncircumscribed margin;

mono-or multifocal, with or without acoustic shadow;

exhibiting the features of presence of glandular tissue architecture with no morphological features of focal lesion;

exhibiting pathological pattern of vascularization in color Doppler or power Doppler.

In this category microscopic verification by means of fine needle aspiration biopsy (FNAB) or core biopsy (CB) is necessary.

For positive results of microscopic assessment further management includes surgical treatment and other complementary methods depending on the result of histopathological verification. The diagnosis of a benign lesion in microscopic examination and in other imaging examinations (e.g. MMG or MMG-MR) is an indication for permanent observation (control examination in 6 months)(.

Lack of compliance between histopathological verification result and other breast imaging examination, including lack of displacement in elastography, is an indication for microscopic reverification(.

The following aspects are counted among BIRADS-usg 4 category:

solid tumors of complex fibroadenomas morphology;

solid focal lesions of morphology similar to fibroadenomas, not fulfilling the criteria of BIRADS-usg 3 lesions;

lactiferous ducts with parietal structures and/or solid lesions in the lumen, insusceptible to compression, with or without high risk nipple discharge;

segmentally dilated lactiferous ducts with uneven walls and parietal structures, insusceptible to transducer compression, independently on the content, with or without high risk nipple discharge;

cysts and fluid filled lesions with parietal structures and/or solid tissue masses, insusceptible to compression of a transducer and immobile during the change of the position of breast during examination;

small hypoechogenic lesions below 10 mm in diameter which based on the morphological features cannot be classified to the categories BIRADS-usg 2 and 3;

BIRADS-usg 3 lesions undergoing enlargement or ultrasound morphology change in control examinations;

inflammatory lesions with no therapeutic effect after treatment;

granular cell tumor;

phyllodes tumor;

diabetic mastopathy.

In fig. 12 the management algorithm for BIRADS-usg 4 category lesions is shown.

Fig. 12

Management algorithm for BIRADS-usg 4 category lesions

Figs. 13–15 present examples of focal lesions classified to BIRADS-usg 4 category.

Fig. 13

Solid, hypoechogenic lesion with prevalence of superiorinferior dimension over lateral-lateral dimension (arrow – superior-inferior dimension, dashed line – lateral-lateral dimension)

Fig. 15

Solid, hypoechogenic lesion, morphologically similar to fibroadenoma, with segmental lack of capsule, of uncircumscribed margin (arrows)

Dilated lactiferous duct with solid lesion in the lumen, insusceptible to compression (arrows)

BIRADS-usg 5 category contains lesions of high (>90%) malignancy probability, of typical malignant lesion morphology( which in US examination is:

solid or solid-fluid filled;

hypoechogenic;

has irregular shape;

spicular or angular margin;

blurred lesion boundary, hyperechogenic halo or infiltrates the skin;

prevalence of superior-inferior dimension over lateral-lateral, calcifications;

pathological pattern of vascularization in color Doppler or power Doppler.

Lesions of this category exhibit at least two of the suspicious lesion features mentioned above.

In this category histopathological verification (core biopsy, mammotomic or open surgical) and oncological assessment in order to plan the treatment (breast conserving therapy, sentinel node biopsy, neoadjuvant chemotherapy) are necessary. Lack of visualization of neoplastic cells in microscopic examination requires another biopsy or surgery directly with microscopic intraoperative examination.

In fig. 16 management algorithm for lesions in BIRADS-usg 5 category is shown.

Fig. 16

Management algorithm for BIRADS-usg 5 category lesions

Figs. 17–19 present examples of focal lesions classified to BIRADS-usg 5 category.

Fig. 17

Infiltrating breast cancer image. Solid, hypoechogenic lesion of speculated margin, with prevalence of superiorinferior dimension over lateral-lateral dimension (cross hairs)

Fig. 19

Ductal invasive cancer image on elastogramme – the lesion insusceptible to deformation (blue color represents tissues insusceptible to deformation, red color – tissues susceptible to deformation, green color – tissues partially susceptible to deformation), BI-RADS 5, Tsukuba 4, SR=6.6

Inflammatory cancer image. Diffuse lesions with skin thickening (arrows with two heads), lymphatic vessels dilation and effusion on the surface of stroma connective tissue fibers and Cooper ligaments (arrows)

Among BIRADS-usg 6 category are counted neoplastic malignant lesions confirmed by biopsy. US examination can be performed directly before surgical treatment or neoadjuvant chemotherapy.

US examination of male breasts

In normal conditions in men glandular tissue does not exist. In breast diseases diagnostics in men the same US machines, transducers and identical technique as in women breast examination is used.

The same examination elements obtain, starting from medical history and physical examination. In case of gynecomastia diagnosis (benign proliferation of lactiferous ducts and periductal stroma), after excluding steatomastia (excessive accumulation of fatty tissue in breasts), scrotum US should be performed in order to exclude testicular tumor. Similarly as in case of breasts in women, BIRADS-usg classification is valid(.

Examination results

The result should contain personal data of the patient examined, date of the examination, name of the healthcare center in which the examination took place, name of the US machine, frequency and type of the transducer. Then the above listed ultrasound features of the lesion (according to PUS and ACR) and information about breast structure, localization of pathological lesions referring to the nipple according to the clock face method (including depth in case of big breasts, measured from the posterior skin surface of breasts towards the center of the lesion) and their size should be included.

The examination description should be ended with a conclusion with the indication of lesion category according to BIRADS-usg classification, with the reference to the examinations performed earlier (e.g. progression, stabilization or regression) and the proposals for performing other examinations (e.g. MMG, MMNG-MR). In cases where several lesions are diagnosed in one patient, e.g. BIRADS-usg 2 and 4, the final examination result indicated is the highest BIRADS-usg category, in this case BIRADS-usg 4.

The examination description should also contain information about lymph nodes of breast lymph drainage (axillary fossae, supra- and infraclavicular fossae).

Where pathological morphological lesions are diagnosed imaging documentation should also be included, referencing in the description the number of attached images. The examination description must be confirmed by the doctor performing the examination with their stamp.

Conclusion

BIRADS-usg classification is a standard in sonomammography breast examination. Assigning lesions to particular degrees provides information about lesion malignancy risk in the relevant category of this classification. At the same time the examining doctor has knowledge of the diagnostic algorithm which applies to the visualized lesion, enabling selection of further diagnostic examinations proposed in the description of this examination or referral of the patient to the appropriate center in order to commence treatment (figs. 1, 8, 12, 16).