Lange Review Ultrasonography Examination, 4th Edition
Chapter 10. Breast Sonography
Lawrence E. Mason
For many years, breast sonography has been an important tool in the management of breast disorders. In recent years, its role in the workup of breast disorders has become more defined as technical advances has improved in spatial and temporal resolution. It is now required by the American College of Radiology that a breast imaging facility offer breast sonography to be considered for accreditation. Without the potentially harmful effects of ionizing radiation, the role of sonography in breast imaging will continue to evolve as technical advances occur.
EPIDEMIOLOGY OF BREAST CANCER1
It is our primary role as sonographers and physicians to provide our best efforts to educate patients on the detection of breast disorders, namely breast cancer. Except for skin cancer, breast cancer is the most common cancer among women. The chance of developing invasive breast cancer at sometime in a woman’s life is about 1 in 8 (13% of women)1. At this time, there are more than 2 million breast cancer survivors in the United States. Women living in North America have the highest rate of breast cancer in the world.
INDICATIONS FOR BREAST SONOGRAPHY
Breast sonography is used as an adjunct to mammography and physical examination. The most common indications to perform an ultrasound exam are the presence of a palpable mass or discovery of an abnormality on mammography. Ultrasound is useful to determine if a mass is cystic or solid, which helps determine management. Ultrasound guidance for aspirations and biopsies is also an indication. Also, ultrasound is the first imaging study in the evaluation of breast mass in pregnant or lactating women, under the age of 30 and in women following mastectomy with a complaint on the side of the mastectomy.
Indications for breast ultrasound include:
• Identification and characterization of palpable abnormalities
• Identification and characterization of clinical and mammographic findings
• Guidance for procedures
• Follow up a finding from a breast MRI or other examination of the breast
All examiners performing breast ultrasound examinations, including those assisting physicians with ultrasound guided breast biopsy procedures, are encouraged to meet minimum criteria (Table 10–1).2
TABLE 10–1 • Criteria for Breast Ultrasound Examinations
When breast sonography is performed by an experienced examiner, patients with breast related complaints can be appropriately triaged for clinical follow up, biopsy or referred for surgery as necessary. However, the detection of breast cancer and breast disorders is a daunting task for the inexperienced breast sonographer and the responsibility for the detection of breast disorders does not rest exclusively on the shoulders of the sonographer. The sonographer’s primary function is to document limited anatomic regions of the breast with knowledge of normal anatomy. In fulfilling this role, the sonographer should be able to bring to the attention of the physician areas of interest that require further evaluation. In the majority of cases, a breast sonogram will require correlation of the sonographic findings with the clinical and mammographic findings prior to the patient leaving the department. This will often necessitate an interaction between the physician and the patient which may include additional imaging.
If the examiner thinks that the sonographic findings do not agree with the indication for the examination (i.e., the exam was performed for a 3 cm mass on a mammogram, but only a 1 cm simple cyst is seen on ultrasound), the patient may be instructed to wait until the physician can verify the concordance of the findings. Alternatively, the patient should be instructed to return at a later time with the understanding that the examination is incomplete.
The physician is not required to be present during breast ultrasound examinations performed by American Registry for Diagnostic Medical Sonography (ARDMS) sonographers or American Registry of Radiologic Technologists (ARRT) with certification in breast sonography. However, a physician must be in the department during breast ultrasound examinations performed by ARRT technologists without advanced registry in breast sonography. In all situations, the physician is ultimately responsible to see that the appropriate images are obtained.2
Equipment used for practice of breast ultrasound should have the following features3:
1. High-resolution, real-time, linear array transducer
2. Center frequency of at least 7 MHz
3. Adjustable focal zone(s)
Linear array, broad bandwidth transducers with a minimum center frequency of 7 MHz are required for breast sonography. However, a center frequency of 10 MHz or greater is preferred. Transducers in the range of 7 to 15 MHz are utilized for breast imaging and the higher frequencies help demonstrate ductal anatomy. Broad bandwidth provides for high resolution superficial scanning with beam penetration to depth settings of 4 cm or greater. At 7.5 MHz, a linear array transducer suitable for breast imaging should have penetration to a depth of at least 4 cm. Higher frequency transducers (>10 MHz) are focused at a depth of 3 cm or less, optimizing resolution of superficial masses. Whereas higher frequencies are more suitable to resolve smaller and superficial structures, the drawback is the frequency-dependent attenuation of deeper breast tissue, which restricts the ability of the beam to adequately display deeper breast structures and lesion detail.
Even with high resolution transducers, use of an acoustic standoff pad often improves the resolution of superficial, nearfield lesions. Copious usage of gel may be more suitable than standoff pads for the evaluation of superficial lesions, particularly those in locations where skin folds preclude an even surface contour. Harmonic and compound imaging techniques may also be useful in addressing artifacts in breast sonography. Spatial resolution of the sonographic images and edge shadowing (i.e., shadowing from adjacent echogenic interfaces) may be improved through the use of spatial compounding, while harmonic imaging may reduce the echoes seen within a lesion to improve the accuracy of diagnosis (i.e., a fluid-filled cystic mass will appear more anechoic with harmonic imaging).
The ability to adjust the focal zone is important for accurate display of breast lesions. If the focal zone is not properly set in the mid portion of the lesion, artifactual echoes may occur within cysts. This can occur despite optimization of other settings.
Generally, the patient is placed in the supine position with the hand on the ipsilateral side of the breast to be examined placed behind the head. The patient is then rolled into a contralateral posterior oblique position. This helps reduce breast thickness and bring posterior lesions closer to the skin surface, thus reducing the limitations of a high frequency transducer. This positioning technique is most effective for lesions in the lateral tissue but is also useful for those in the medial tissue. For evaluation of the medial breast tissue, placing the patient’s ipsilateral arm by the side often optimizes the examination. Rolling the patient into a posterior oblique position ipsilateral to the side to be examined may also be helpful for examination of the medial tissue and this may be a more comfortable position for a prolonged examination.
Sonographic Evaluation of Palpable Lesions
Patients are often referred for sonographic evaluation of areas of palpable concern. These areas may be noticeable to the patient, but often these areas are noticeable only to the referring clinician who has requested the examination. This scenario poses an issue to the sonographer as the sonographer may not be able to elicit any true concerns from the patient. For this reason, it is recommended that sonographers attempt to receive graphic or written documentation of where the area of interest is with respect to the nipple/areolar complex (i.e., distance from the nipple) and according to the clock face designation of the breast.
In addition, it may be necessary for the interpreting physician to verify by physical examination that the area to be evaluated is the area of clinical interest. This may necessitate a physical examination by a physician prior to the patient leaving the department. Correlation of imaging findings with clinical findings is paramount to ensure that an abnormality is not overlooked.
The technique of the examination of a palpable lesion is not significantly different than that of a nonpalpable lesion. For lesions that can be reliably palpated, the examiner should attempt to fix the lesion between two fingers. This will aid in decreasing the mobility of a lesion and improve diagnostic accuracy. This technique is especially useful for lesions that are superficial, mobile or subjectively small (i.e., <1 cm). For lesions within the skin, use of a standoff pad or a generous amount of gel may be necessary. At the least, the focal zone should be brought as close to the surface as possible, the depth should be minimized and the image appropriately magnified.
Also, examination of the area of palpable interest is often facilitated if the area is localized by physical examination with the patient in the position which allows the lesion to be most easily palpated. The patient may then be repositioned as necessary. In the evaluation of an area of palpable interest, the examination may be performed with the patient in a variety of recumbent, upright and standing positions to assure the examiner that the area of interest is in fact being appropriately evaluated.
IDENTIFICATION, LABELING AND DOCUMENTATION OF THE EXAM
Each examination is required to note the following on each image3:
• Patient’s first and last names (required)
• Identification number and/or date of birth (required)
• Examination date (required)
• Facility name and location
• Designation of right or left breast
• Location of the lesion or area of interest using diagrammatic, clock face or other consistent notation, including distance from the nipple
• Scan plane/transducer orientation-radial/antiradial; longitudinal/transverse (required)
• Initials (or ID) of the sonographer performing the breast ultrasound exam and/or the physician performing the biopsy Documentation of a mass/lesion requires the following:
• Each lesion should be noted in two orthogonal planes, both with and without calipers
• The maximal dimension of the mass should be measured as should the mass in three planes
• The focal zone should be set to the depth of the lesion
All abnormalities should be documented in two orthogonal planes. For the breast, imaging and description of lesions in the radial and anti-radial plane correlates with the ductal anatomy of the breast as both have an axis radiating from the nipple in a spoke-like fashion. Using radial and antiradial imaging with notation of clock face position and distance from the nipple allows a finding to be accurately localized. The clock face position can be used to identify the location of a lesion in the breast. It is important to remember that the clock face is superimposed, without reorientation, on both breasts in the same manner, thus the lateral right breast and medial left breast correspond to the 9 o’clock position.
The distance of the lesion from the nipple in centimeters is also required for proper documentation. To estimate the distance from the nipple, the length of the transducer footprint should be known and an estimate of the distance from the nipple can be assessed by knowledge of the transducer position (i.e., 1.5 transducer lengths from the nipple equals 9 cm from the nipple if the transducer is 6 cm in length).
Also, at least two sets of images of a lesion should be obtained: one with and one without measurements (calipers obscure the marginal detail). When documenting a negative examination of an area of palpable concern, an image should be taken at the exact location of the palpable area, and clearly labeled to indicate that the image corresponds to the palpable area. If the ultrasound examination is being performed for a targeted lesion or palpable abnormality, the corresponding quadrant of the breast should be examined. If a breast survey exam of the entire breast is performed, images should be acquired from all four quadrants. Images labeled 12, 3, 6, and 9 o’clock or upper outer, upper inner, lower inner or lower outer quadrant are appropriate.
Documentation of Ultrasound Guided Biopsies
Biopsies performed with the assistance of ultrasound may be performed with or without a device which employs a forceful thrust through breast tissue into or through the area of interest. The mechanism by which the biopsy device produces a forceful thrust is referred to as ‘firing.’ Often, biopsy devices that do not feature a firing mechanism have the ability to suction tissue into a portion of the needle. After suctioning tissue into the needle, a cutting device is activated thus producing a tissue sample. These instruments are referred to as ‘vacuum-assisted’ biopsy devices. The necessary image documentation differs slightly depending upon which type of device is used to perform a biopsy. (Table 10–2)4
TABLE 10–2 • Required Clinical Images: Core Needle Biopsy (Non-vacuum Vacuum)
CORRELATING THE FINDINGS
The size and location of all lesions should be closely correlated with the abnormalities found on physical exam and other imaging modalities, namely mammography. Often, sonographic findings may be noted that were not previously identified on other imaging modalities. It is important to note these findings while continuing a search for an abnormality that would correlate with the reason for which the examination was requested. If this was an imaging finding, consultation with the radiologist/interpreting physician is necessary prior to the patient leaving the department. This will help reduce interpretation error and reduce delays in the diagnosis of breast diseases, namely cancer. Usually, size and location are the two lesion characteristics which aid the most in establishing confidence that what is seen sonographically correlates with what is seen on other modalities.
The breast is a glandular organ composed primarily of fat, fibrous and glandular tissue with the capacity to alter its composition as a response to various factors. Hormonal stimuli effect the premenopausal changes and the age-related replacement of the glandular elements with fatty tissue. These changes contribute to the variable sonographic appearance of breast tissue at different stages of development. The fibroglandular composition of the breast is the primary variable that determines the attenuation characteristics of the breast tissue.
The breast parenchymal structure consists of 15–20 lobes that converge at the nipple in a radial arrangement, similar to the spokes of a wheel. One major duct, with an approximate 2 mm diameter, drains each lobe. Typically, 5–10 major collecting ducts open at the nipple.
The arterial supply is derived from numerous perforating arterial branches including the internal thoracic (internal mammary), lateral thoracic, and 3rd–5th intercostals arteries. The most medial of these is the internal thoracic (internal mammary) artery.
Sonographic Anatomy of the Breast
Skin. Skin is seen as two thin echogenic lines bordering a central hypoechoic region (Figs. 10–1 and 10–2). Normal thickness is <2 mm, however, in the lower breast at the junction of the inferior skin of the breast and the chest wall (inframammary fold) and in the region of the nipple (periareolar) up to 3 mm thickness is allowed.
FIGURE 10–1. Cooper’s ligaments extend from the parenchyma to the skin. Note the superficial rim of echogenicity at the rib and deeper shadow associated with calcification.
FIGURE 10–2. Prominent ducts are normally seen in the retroareolar region.
Cooper’s Ligaments. Cooper’s ligaments are seen as thin, discrete echogenic lines radiating through the breast parenchyma extending toward the skin (Figs. 10–1 and 10–2). These ligaments help attach the parenchyma to the overlying skin and are best seen in the subcutaneous region where surrounding hypoechoic fat helps better visualize their appearance. They are often difficult to visualize within the hyperechoic parenchyma.
Breast Parenchyma (Fibroglandular Tissue). The breast parenchyma appears as areas of increased echogenicity located between the subcutaneous fat and retromammary fat (Figs. 10–2 and 10–3). The majority of the parenchyma is in the area deep to the nipple and in the lateral breast. Fibroglandular tissue usually occupies the majority of the volume of the breast in younger women and decreases with age. Hormone replacement therapy in postmenopausal women contributes to the persistence of fibroglandular tissue within the breast.
FIGURE 10–3. The typical appearance of fat (subcutaneous and retromammary) and parenchyma.
Duct. Ducts are seen as tubular, anechoic structures visible most prominently in the region beneath the nipple where they typically measure 2–3 mm in greatest diameter (Fig. 10–2). Ductal ectasia exists when ducts are >3 mm in diameter (Fig. 10–4). Ducts increase in diameter as a normal phenomenon during pregnancy and lactation. Evaluation for the presence of an intraductal mass is indicated if there is ductal ectasia in other settings (Fig. 10–5).
FIGURE 10–4. Dilated ducts may be seen without a detectable abnormality.
FIGURE 10–5. Dilated ducts may be seen with a detectable abnormality.
Fat. Fat is seen primarily in the subcutaneous and retromammary (between parenchyma and chest wall) regions (Figs. 10–2 and 10–3). The gain setting of the ultrasound unit should be set so that fat is hypoechoic with a medium to light gray appearance. The amount of fat within the breast decreases during pregnancy and lactation.
Ribs. The ribs appear as hypoechoic structures with a superficial curvilinear echogenic line on the side closest to the chest muscles and breast (Fig. 10–1). Marked posterior acoustic shadowing is present deep to the rib. Often, a central echogenic focus may be seen within the hypoechoic rib. The ribs are positioned immediately deep to the chest wall muscles.
Chest Wall Muscles. The chest wall muscles are located deep to the breast tissue and superficial to the ribs. Morphologically, they are plate-like and demonstrate a striated appearance with a dominant hypoechoic echotexture and internal echogenic lines (Fig. 10–6). The chest wall musculature is composed primarily of the pectoralis muscles which extend horizontally from a midline location toward the axillae.
FIGURE 10–6. Typical appearance of the pectoralis muscle. Note the oval, parallel, circumscribed mass. This proved to be a benign fibroadenoma.
Lymph Nodes. Lymph nodes (Fig. 10–7) are oval, beanshaped structures with a hypoechoic periphery (cortex) and a central echogenic region (hilum). These structures are normal when seen in the breast, particularly in the upper outer quadrant and axilla. Mass-like thickening of the peripheral cortex, gross change in shape (i.e., becomes globular) and absence of the echogenic hilum are abnormal findings. Assessment with color Doppler often yields detectable flow at the hilum where vessels enter and exit the lymph node (Fig. 10–8).
FIGURE 10–7. The typical appearance of an intramammary lymph node on gray-scale imaging is see in this image. Note the bean-shape of the lymph node with an echogenic hilum and hypoechoic periphery.
FIGURE 10–8. The typical appearance of an intramammary lymph node on Doppler imaging is see in this image. Note the kidney-bean shape with an echogenic hilum and hypoechoic periphery. Color Doppler sonography often depicts a vessel coursing into the hilum.
Nipple. The nipple often produces posterior acoustic shadowing distal to underlying tissue in normal circumstances. Proper examination requires a standoff pad or abundant gel for effective visualization (Fig. 10–9).
FIGURE 10–9. Imaging the nipple often requires the use of a standoff pad or copious amounts of gel.
Appropriate description of a lesion’s characteristics is paramount for the communication of an examination’s findings. Each characteristic should be assessed individually. Keeping characteristics separate under different descriptor categories helps get an overall impression of the lesion in question. Alternatively, the presence of a suspicious descriptor should prompt a more thorough evaluation to ensure that no other suspicious characteristics exist. An accurate portrayal of the lesion in question is needed to determine the most appropriate management and it is not infrequent that a single suspicious characteristic prompts intervention which can lead to the diagnosis of a malignancy. Characteristics suggestive of a malignant and benign processes (Tables 10–3 and 10–4) as well as those typically describing a simple cyst (Table 10–5) can be found in the included tables.
TABLE 10–3 Descriptors Suggestive of Malignancy
TABLE 10–4 Descriptors Suggestive of Benignancy
TABLE 10–5 Descriptors of A Simple Cyst
Lesion shape may be classified as round or oval (Table 10–5). Round masses have a spherical or globular shape (Fig. 10–10). Oval masses have an elliptical shape and may have two or three gentle undulations (Fig. 10–11). All other masses are characterized as irregular.
FIGURE 10–10. Round circumscribed, anechoic masses with posterior acoustic enhancement are seen in this image. These masses represent cysts.
FIGURE 10–11. Oval circumscribed, anechoic mass with enhanced through transmission and distal acoustic enhancement.
Parallel orientation (Fig. 10–13) describes a mass which has its longest dimension parallel to the skin i.e., wider than tall. Nonparallel orientation describes a mass whose long axis is not parallel to the skin, i.e., taller than wide; this includes round lesions.
FIGURE 10–13. Note the oval, circumscribed, parallel, hypoechoic mass depicted in this image. No surrounding tissue abnormality is seen. This was a benign fibroadenoma.
A mass described as circumscribed is one whose margins are well defined and sharp with an abrupt transition between the mass and the adjacent tissue. The margins of a non-circumscribed mass can be described as indistinct (no clear demarcation with surrounding tissue), angular (sharp corners with adjacent tissue), microlobulated (scalloped appearance) or spiculated (sharp lines projecting from the mass) (Fig. 10–12).
FIGURE 10–12. An irregular, complex mass with spiculated and angular margins and an echogenic halo is depicted. Note the focal zone (black arrow at the right of the image) positioned at the center of the mass. This was an invasive cancer.
The presence of an echogenic transition zone interposed between the mass and the adjacent tissue is referred to as an ‘echogenic halo’ (Fig. 10–12). Its absence suggests the presence of an abrupt interface (Figs. 10–11 and 10–13).
Anechoic defines a mass without any internal echoes (Fig. 10–11). Hyperechoic describes a mass whose interior has elements with increased echogenicity relative to fat or similar echogenicity to that of fibroglandular tissue (Fig. 10–14). Isoechoic describes a mass with echogenicity the same as fat, while hypoechoic describes a mass with low level internal echoes present that are less than the echogenicity of fat (Fig. 10–13). Complex describes a mass with both anechoic and hypo-/iso-/hyperechoic components (Fig. 10–12).
FIGURE 10–14. Free silicone can be seen in axillary or intramammary lymph nodes or in breast tissue. There is poor visualization of structures beneath the silicone-filled lymph nodes.
Posterior Acoustic Features5
If there is increased echogenicity of the tissue deep to the mass, this is termed posterior acoustic enhancement (Figs. 10–10 and 10–11). A reduction in echogenicity of the tissue deep to the mass (not including the tissue deep to the edges of the mass) is termed posterior acoustic shadowing. Some lesions do not demonstrate posterior acoustic features and others demonstrate a combination of such features.
Dilatation of the ducts (ductal ectasia, Fig. 10–4) or changes in the branching pattern can be seen with certain processes. Also, Cooper’s ligament changes can manifest as an increase in thickness or disruption, particularly in the presence of an inflammatory process. As the breast retains fluid, edema may manifest as branching hypoechoic lines throughout an enlarged breast (Fig. 10–15). Disruption of normal anatomic planes is termed architectural distortion (Fig. 10–16) and is commonly seen in malignancy and in postsurgical cases. Skin thickening (Fig. 10–15), whether focal or diffuse, is also noteworthy as is evidence of skin retraction in which the skin surface may have an irregular, pulled-in appearance.
FIGURE 10–15. In this image, the skin is thickened and fluid is seen beneath the skin surface.
FIGURE 10–16. Post surgical breast scar. Distortion of the tissue with an irregular hypoechoic appearance in this image due to a surgical scar.
Calcifications (Fig. 10–17) are often difficult to visualize and characterize with ultrasound. They appear as echogenic foci whose ability to produce posterior acoustic shadowing is primarily dependant upon size. Calcifications which measure >0.5 mm in diameter are termed macrocalcifications and those which measure <0.5 mm in diameter are termed microcalcifications. If calcifications are visualized, it is important to note whether they are seen in association with a mass.
FIGURE 10–17. Discrete echogenic foci seen in this image represent calcifications.
Clustered microcysts often have an appearance of a cluster of tiny anechoic foci of diameter >2–3 mm with thin (<0.5 mm thickness) intervening septations and no solid contents. Complicated cysts (Fig. 10–18) are most commonly characterized as masses with homogeneous, low-level internal echoes which may have fluid-fluid levels that shift with changes in the patient’s position. Masses in or on the skin include sebaceous or epidermal inclusion cysts; these are often seen as entities at least partially contiguous with the dermis. The echogenic lines of the skin may separate to include a portion of the mass, thus confirming the location of the mass within the skin. Foreign bodies such as surgical clips, biopsy markers, implants (Fig. 10–19) or extruded implant material such as silicone should be described. Surgical clips and biopsy markers appear as discrete echogenic foci with variable posterior acoustic shadowing primarily dependent on size. Extruded silicone has a typical ‘dirty shadowing’ or ‘snowstorm’ appearance and can be seen in regional lymph nodes (Fig. 10–14).
FIGURE 10–18. Complicated breast cyst. Multiple hyperechoic foci are seen in this largely anechoic mass representative of a complicated cyst.
FIGURE 10–19. The capsule of an intact breast implant with overlying extracapsular fluid is depicted in this image. Fluid may be seen adjacent to normal, intact implants and does not signify the presence of a rupture.
Detecting vascularity within a lesion can help determine whether are solid components. However, the absence of Doppler flow does not exclude the presence of a solid portion. Reactive tissue changes from a nearby process may manifest as diffusely increased vascularity and demonstrate an increased Doppler signal.
Cysts are the most common breast masses, particularly in premenopausal women. The classic description of a simple cyst is that of a round, circumscribed, anechoic mass with posterior acoustic enhancement and no adjacent architectural distortion. Due to their fluid-filled nature, cysts lack internal vascularity on Doppler evaluation and can usually be deformed with gentle pressure. When any of these characteristics are not present, the diagnosis of a cyst should be in question. As experience grows, it may be seen that cysts assume a variety of shapes and have a range of echogenicity. These atypical characteristics may be suspicious depending upon the circumstance and may prompt an aspiration under sonographic guidance. If the cyst collapses completely following aspiration, this is diagnostic of a breast cyst. However if there is incomplete collapse of the cyst or a solid portion is seen in or adjacent to the cyst, biopsy of the solid portion is indicated. Recurrent, symptomatic cysts may be surgically excised. Hemorrhagic cysts often contain echogenic fluid or debris which may appear solid, thus prompting intervention when detected.
Fibroadenomas are the most common solid breast masses. The classic description of a fibroadenoma is that of an oval, circumscribed, hypoechoic mass with its long axis oriented parallel to the breast tissue. A macrolobulated (i.e., a few large lobulations) contour may be seen. The peak age for detection is ages 20 to 30 years, but they can be seen well into the eighth and ninth decades of life. Solid masses often have overlapping features, thus making the exclusion of a different entity, particularly breast carcinoma, difficult. Biopsy is often needed to obtain a diagnosis. Certain characteristics of a solid mass such as recurrence following removal, postmenopausal enlargement and >2 cm of growth in a year are atypical findings which raise the suspicion for the presence of a mass other than a benign fibroadenoma.
The sonographic detection of breast cancer is of utmost importance and not without pitfalls. A full description of the appearance of breast carcinoma would be beyond the scope of this text. Additionally, breast masses can appear different with variations in tissue density and echogenicity. Masses associated with an illdefined border, an echogenic halo, margins that are sharp and angular, spiculation, posterior acoustic shadowing or adjacent architectural distortion are suspicious for malignancy. Also, any solid mass seen within a duct is suspicious and should be further evaluated. Subtle changes in the architecture of the breast (i.e., thickening of the adjacent Cooper’s ligaments) are often the best clues that an aggressive, malignant process is ongoing, but detection of such findings often requires an experienced examiner with a discriminating eye.
Breast sonography is a useful tool in the workup of breast disorders. As operator experience increases, the ability of the sonographer to differentiate subtle abnormalities of the breast will develop. With an understanding of technique and breast anatomy, adherence to the examination requirements and knowledge of the necessary language for appropriate characterization of the findings, a solid foundation for a developing breast sonographer is set.
1. American Cancer Society. Overview: Breast Cancer. 2006. Available: http://www.cancer.org/docroot/CRI/CRI_2_1xasp?dt=5(09/26/2006).
2. American College of Radiolog. Breast Ultrasound Accreditation Program requirements. 2007. Available: http://www.acr.org/accreditation/breast/breast_ultrasound_regs.aspx).
3. American College of Radiology. ACR Practice Guidelines for the Performance of a Breast Ultrasound Examination (Revised 2002). Reston, VA: Guidelines and Standards Committee; 1994.
4. American College of Radiology ACR Practice Guideline for Performance of Ultrasound-Guided Percutaneous Breast Interventional Procedure (Amended 2006). Reston, VA: 1996.
5. American college of Radiology. ACR BI-RAD®—US Lexicon Classification Form Reston, VA:2006.