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Holdorf PhD, MPA, RDMS (Ob/Gyn, Ab, BR), RVT, LRT(AS) Module 5 Sonography Breast Sonography Sonography has been shown to be highly valuable in the diagnosis and management of breast disease. The use of breast sonography as a screening tool for breast cancer, especially for younger patients, continues to gain popularity. Using sonography as a screening tool for all patients is highly debated. There are several approaches for using Breast Sonography or Breast Ultrasound (BUS) in the diagnosis of disease: Targeted Examination and Whole Breast Examination. Targeted Exam Sonography is used to evaluate a specific area of breast only. Usually performed as a follow-up to mammography. The entire breast and opposite breast are not evaluated. Whole Breast Exam Sonography is used to survey the entire breast for the presence of disease, often with attention to a specific area. Sonography also plays a crucial role in the management of breast disease. Real-time visualization of the needle’s path using 2D or 3D/4D technique allows sonography to guide interventional procedures. Indications for Breast Sonography Characterize masses as cystic or solid Follow-up to Mammography Evaluate palpable masses in young women (less than 30) avoiding mammography. Evaluate masses in pregnant and lactating women. Evaluate dense breast tissue Evaluate a mass seen in only one view on mammography Evaluate inflammation Evaluate the irradiated breast Evaluate the augmented breast Evaluate axillary lymph nodes Evaluate nipple discharge Evaluate patients when mammography is not possible Serial evaluation of a benign mass Evaluate the male breast Guide interventional procedures Patient History The sonographic examination begins with a through patient history. Sonographers should use a questioning technique to obtain as much personal history that the patient can provide. Patient history should include: Patient’s name Personal history of breast disease Personal history of cancer Family history of breast disease Medications: especially hormones Previous breast surgeries and findings Breast pain and location Findings from monthly breast self-examinations (BSE) Findings from clinical breast examination (CBE) The sonographer should also make a visual inspection of the breast for: Size, shape, contour, and symmetry Skin redness, edema, dimpling or retraction, protrusions, and thickening. Nipple retraction and discharge Surgical scars If palpable lump is noted, the sonographer should document: Location Size Shape (round, oval, lobulated, or irregular) Consistency of lump (soft, rubbery, firm, hard, gritty) Mobility (movable or fixed) Distanced from the nipple Date when it was first discovered and has it changed over time. If a previous Mammogram or BUS has been performed, the prior examination should be reviewed by the sonographer for comparison. It is essential that size, shape, and density/echogenicity of a mass are consistent from one exam to the next. Skin dimpling Positioning (all is underlined) The patient is examined in a supine or supine-oblique position with the ipsilateral (same) arm raised above the head. A sponge or pillow may be used to support the patient’s back. This maneuver allows a more even distribution of the breast tissue over the chest wall with the nipple centered. The thickness of the breast is minimized and allows adequate penetration by the sound beam. This is also identical to the position used during open excisional biopsies. The right breast is best evaluated with the patient in the LPO (left posterior oblique) position. The left breast is best evaluated in the RPO (right posterior oblique) position. The medial aspect of the breast is effectively evaluated with the patient lying in the supine position. For larger breasted patients, lateral lesions may require a steep oblique or decubitus position. A sitting or upright position may be used as an alternative patient position to simulate the cranio-caudal (CC) mammographic view. Transducer Pressure Moderate transducer pressure should be applied during scanning. This will: Improve sound transmission Improve detail or resolution Decrease the tissue depth for better penetration May eliminate some artifacts Scan Planes (all underlined) Sagittal and transverse scan planes may be used in breast imaging. Sagittal and transverse scan planes correspond to conventional sagittal and transverse to the body. Radial and Anti-radial scan planes may also be used. Radial and Anti-radial scan planes correlate with the direction of the ductal system of the breast. Radial is longitudinal or parallel with the ducts and anti-radial is transverse or perpendicular to the ducts. Radial is the AIUM recommended scan plane for breast imaging. Important note: If a solid lesion is found, the sonographer should scan the lesion in the radial and anti-radial planes. This allows visualization of tumor or ductal extensions branching toward or toward the nipple. These extensions could be missed in the sagittal and transverse planes. Annotation Labeling your images can be very time consuming, yet very helpful for precise location of a lesion and followup studies. Most sonography departments use the standard clock method for identifying the location of lesions. This provides a more detailed description than the quadrant method. SA may denote the subareolar region, and AX may refer to the axillary region. In addition to the clock method, some Sonographers also use the 123 and ABC methods of providing more exact location. 123 Method The 123 method describes the location of a lesion in comparison to its distance from the nipple. Location 1 is near the nipple. Location 2 is mid distance from the nipple. Location 3 is in the periphery of the breast. 123 Method ABC Method The ABC method describes the depth of a lesion. Location A is superficial Location B is at mid depth (likely within the mammary layer) Location C is near the chest wall. Stand-off Pad A stand-off pad creates distance between the face of the probe and the skin surface. Therefore, the fixed elevation plane focus is moved more superficially. This allows improved focusing and greater detail in the superficial layers of the breast. A stand-off pad improves imaging of: Superficial tumors of cysts Superficial vessels Superficial ducts Skin lesions Skin thickening Scanning surgical specimens Types of Stand-off Techniques include: Commercially produced gel pads Water bag Large “glob” of gel (used for imaging the nipple) Stand-off transducer attachments The ideal stand-off pad thickness for breast imaging is 1cm This places the elevation plane focus of a 10MHz transducer at approximately 0.5cm depth within the breast. Normal Sonographic Appearance The echogenicity of breast tissue will vary with the amount and location of fat and fibrous tissue due to patient age, functional state of the breasts, and body habitus. For example, young women will tend to have more dense fibroglandular tissue that appears HYPERECHOIC. Older women tend to have more fatty replacement that appears ISOECHOIC. The lactating patient will have greater density appearing HYPERECHOIC. The obese patient will have more fat appearing ISOECHOIC and the extremely thin patient will appear to have more dense tissue appearing HYPERECHOIC. The breast is composed of three major tissue types seen on sonography: Fat (superficial, intraparenchymal, and retromammary) Epithelium (TDLU and Acini) Stromal Tissue Loose stromal tissue (intralobular and periductal) Dense stromal tissue (interlobular and Cooper’s ligaments. Echogenicity Skin - HYPERECHOIC Thickness of 0.5 to 2mm. May see slight increase in echogenicity at the gel/skin interface (sound beam entrance) and the skin/superficial fat interface (exit). Fat – MEDIUM GRAY Found within the superficial layer, parenchymal layer, and retromammary layer. All structures are compared to the mid-level echogenicity of fat. Cooper’s Ligaments – HYPERECHOIC Considered part of the dense connective tissue. Best seen in the subcutaneous fat layer as a thin, wavy linear structure. May produce shadowing artifact- try changing the angle of the transducer. Cooper’s ligament Echogenicity continued… Glandular Epithelium - ISOECHOIC TO MILDLY HYPOECHOIC Consists of TDLUs and acini found within the parenchymal layer Dense Fibroglandular Tissue – HYPERECHOIC Fibroglandular tissues are a combination of glandular epithelium and both loose and dense connective tissue in the parenchymal layer. Lactiferous Ducts – HYPOECHOIC If dilated and fluid-filled, ducts may appear anechoic. Use Doppler technique to distinguish ducts from vessels. Pectoralis Muscles – HYPOECHOIC HYPERECHOIC STRIATIONS with Found deep to the retromammary layer Ribs – HYPERECHOIC SHADOWING with POSTERIOR Found deep to the retromammary layer. Lymph nodes – HYPOECHOIC CORTEX WITH HYPERECHOIC FATTY HILUM Oval or kidney (reniform) shaped. Calcifications – MARKEDLY HYPERECHOIC Cysts – ANECHOIC TO HYPOECHOIC Simple cysts will appear anechoic and complicated or debris-filled cysts will appear hypoechoic Benign Lesions – MILDLY HYPOECHOIC, ISOECHOIC, or MILDLY HYPERECHOIC In general, benign lesions are similar to the echogenicity of fat and epithelium. Malignant lesions HYPOECHOIC – MILDLY TO MARKEDLY In general, malignant lesions are less echogenic than benign lesions. Due to the overlap in echogenicities between benign and malignant tissues, BUS is not capable of distinguishing benign from malignant. Other characteristics must also be considered. Fibrous Planes The normal adult female breast has distinct fibrous tissue planes from skin surface to chest wall. These anatomic layers or fibrous planes were described as: Skin Subcutaneous (premammary) layer Mammary Layer Retromammary Space Muscle Layers Chest Wall Sonography has the ability to visualize and evaluate these fibrous planes. The integrity of the plane is important to note with breast disease. In general , benign diseases will not cross fibrous planes. They are more likely to deviate the planes. Malignant diseases may cross fibrous planes and have a tendency to grow toward the skin. This is due to a cancer’s invasive or infiltrative ability. Dynamic Imaging Opportunities Compression Echo-Palpation Fremitus Dynamic Examination Sonography is a dynamic examination. It offers the ability to visualize structures in real-time as they move, change shape, react to gravity, and demonstrate flow. Therefore, the sonographer has the ability to interrogate tissues using a variety of dynamic techniques. COMPRESSION: In addition to improving quality and eliminating artifacts, compression can be used to evaluate effects on a mass. When compression or transducer pressure is applied directly over a lesion: Cysts will change shape Soft, benign lesions tend to change shape (Lipoma) Hard, malignant lesions will not change shape Internal echoes within a benign lesion may become more uniform Debris within cysts or ducts may be better visualized. Echo- Palpation Echo-Palpation or sono-palpation is a technique used to isolate a palpable mass. The sonographer immobilizes a mass between two fingers while scanning with the opposite hand. This assures visualization of the correct structure. It also allows the examiner to palpate the lesion during real-time evaluation. This technique can also be used to assess the mobility of a lesion by attempting to move the mass with two fingers while scanning simultaneously. Benign masses may move slightly within the tissues. Malignant masses tend to be fixed. Fremitus Fremitus is also know as Vibration Doppler Imaging (VDI). It is the vibration of tissues (usually in the chest) during speech. A fremitus maneuver or technique can be used to evaluate breast tissue during real-time scanning. Used in combination with power Doppler, normal breast tissues vibrate creating motion, thus producing a Doppler signal. A Foreign tissue will not vibrate and will not demonstrate a signal. Fremitus Technique: Isolate tissue in question Turn on power Doppler (use a decreased Doppler gain setting – color saturation could FILL-IN a true tumor Have the patient hum or say EEEEE Normal breast tissues vibrate creating a Doppler signal. Tumors will not vibrate demonstrating no signal. The Fremitus maneuver can be helpful when evaluating: Normal fat lobules Normal tissue versus isoechoic tumor Ill-defined borders Non-visualized posterior margin Benign versus malignant characteristics 3D/4D Breast Sonography Three-dimensional (3D) technology offers imaging in three orthogonal planes, including the routinely nonvisualized coronal plane. It is significant for identifying spiculation. 3D scanning can also offer tomographic image display. Four-dimensional (4D) technology offers real-time 3D imaging and can significantly improve ultrasoundguided interventional techniques. 3D of breast cancer Sonographic Features of Benign Disease Shape and orientation Round Characteristic of tense cysts and small, solid, benign tumors Oval or Ellipsoid Typical of non-tense cysts and most benign tumors Horizontal orientation Also known as WIDER-THAN TALL, Length > AP, or Width > Depth Long axis of the tumor is parallel to chest wall Benign tumors tend to grow within or along the tissue plane (not crossing) Margins Smooth, well-defined, or circumscribed Indicates the tumor is displacing adjacent tissues rather than invading Macrolobulation Gentle, large lobulations Border Thickness Thin, echogenic pseudocapsule Caused by compression or rimming of adjacent tissues around the lesion (Opposite of Invasion) Echogenicity Anechoic Simple cyst Hyperechoic Indicates a fibroglandular pseudomass or lipoma Mildly hypoechoic, isoechoic, or mildly hyperechoic Solid, benign tumors Contradiction: some malignant tumors have same echogenicity Homogeneous Internal echoes are a consistent, single shade of gray Contradiction: some highly cellular malignant lesions may appear homogeneous Artifacts Acoustic Enhancement Caused by an increase in sound energy while passing through tissue Most are cysts Solid, benign tumors may also display enhancement. This is due to more uniform travel through the tumor than through the surrounding tissue Enhancement artifact offers good visualization of the posterior tumor wall. Contradiction: some highly cellular malignant tumors may have A.E. Edge Shadowing Attenuation of the sound beam at the lateral margins of a mass due to refraction. Doppler Cysts have no internal flow Benign, solid masses demonstrate no flow or are hypovascular (little Doppler signal) Fibrous Planes Benign lesions tend to grow within or along fibrous planes, compressing or displacing adjacent tissues Ducts Ducts generally measure less than 3mm and increase in size as they run toward the nipple Dilation or Duct Ectasia may occur due to a variety of normal conditions: Lactation, 3rd trimester of pregnancy, and perimenopausal changes Duct dilatation may also be due to mastitis and fibrocystic change or be seen with papillomas Contradiction: some duct dilatation may be associated with ductal carcinoma or papillary carcinoma. Dilated Ducts of a lactating patient Ductal Ectasia Calcifications Large calcifications causing shadowing artifact are typically a benign characteristic Usually have a diffuse pattern May arise from scarring, necrosis, hemorrhage, cysts or fibroadenomas Small curvilnear calcifications in the gravity-dependent portion of a cyst, likely represent milk of calcium Contradiction: clustered microcalcifications are common with breast cancer. Large benign calcification of the breast Lymph Nodes See normal appearance of fatty hilum and cortex Less than 2cm in size (although size not reliable) Low resistive Doppler waveform As a lymph node becomes more fatty, the cortex thins and the hilum is more prominent on sonography Sonographic Features of Malignant Disease Shape and orientation Irregular shape Most common malignant shape Usually with angles and straight lines Spiculated Most specific feature of a malignancy on Sonography and Mammography Straight lines which radiate from the center of the tumor Vertical Orientation Also known as TALLER-THAN-WIDE, AP>Length, Depth>Width Long axis of tumor is perpendicular to chest wall Demonstrates invasion into other tissue planes Margins Microlobulation Multiple small lobulations (usually 2mm) Ill-defined Obscured or indistinct margins that are poorly defined Usually indicates tumor invasion into surrounding tissues Angular Irregular, jagged margins Highly sensitive for malignancy Spiculated Straight lines which radiate from the center of a tumor Radial Extensions Duct extension – extension of tumor into a duct coursing toward the nipple Branch pattern – extension of tumor into a duct coursing away from the nipple (usually involves multiple ducts) Must be scanning in radial plane. Border Thickness Thick, echogenic halo Usually indicates tumor invasion with fibrotic host response (Desmoplasia = the growth of fibrous or connective tissue) Echogenicity Mildly to Markedly hypoechoic Also described as ALMOST ECHOGENIC Highly suspicious for malignancy Heterogeneous Internal echoes are not consistent having many gray shades Contradiction: benign complex cysts and benign tumors with internal fibrosis, degeneration or calcifications may appear heterogeneous. Artifacts Shadowing Most solid, malignant tumors demonstrate some degree of shadowing Shadowing may cause limited or lack of visualization of the posterior tumor wall. Shadowing may arise from only part of the lesion. Contradiction: Cooper’s ligaments may cause shadowing due to refraction. Contradiction: Some benign lesions such as calcified fibroadenoma, radial scar, and fat necrosis may cause shadowing Doppler Angiogenesis is the ability of a malignancy to develop new blood vessels (tumor vessels) Malignant lesions tend to demonstrate more peripheral and internal blood flow with increased Doppler signal Contradiction: Inflammation may demonstrate hypervascularity with an increased Doppler signal. Conventional or power Doppler are not reliable in distinguishing benign from malignant lesions. Tumor vessels (formed from angiogenesis) have only two layers of their walls. They lack a basement membrane of adventitia. Fibrous planes Malignant lesions tend to invade tissue planes and disrupt adjacent tissues. Some tumors may invade the superficial fascia allowing spread to the superficial structures May see skin dimpling, skin thickening, nipple retraction, or retraction of Cooper’s ligaments. Tumors may also invade the deep fascia and pectoral fascia planes Contradiction: some benign processes such as inflammation or trauma may interrupt planes Crossing fibrous planes: Invasive ductal carcinoma Ducts Malignant lesions may invade the ducts causing dilatation, internal echoes or debris, and irregular tumor extension within the duct. Radial scanning should be performed to assess duct extension and branch pattern. Calcifications Small, micorcalcifications are often associated with malignancy These clustered micorcalcifications may be visualized within a tumor on BUS (mammography is superior, however, in detecting calcifications) Lymph Nodes Loss of definition of fatty hilum Enlargement > 2cm Micorcalcifications High resistive Doppler waveform As a lymph node becomes cancerous, it generally enlarges and loses definition of the fatty hilum Automated Breast Ultrasound ABUS Automated Breast Ultrasound (ABUS) systems may be approved for breast cancer screening as an adjunct to mammography for asymptomatic women with dense breast tissue. The ABUS system previously received approval for this indication in Canada and Europe. In the U.S., the device was earlier only approved for use in these women for diagnostic purposes.
