Breast Imaging Flashcards

Question

BI-RADS Assessment Categories

Answer 1

Category 0: Need additional imaging - Additional imaging evaluation (such as spot compression, magnification, special mammographic views, or ultrasound) and/or prior mammograms are necessary before a final assessment can be assigned. Category 0 is only appropriate for screening. All diagnostic mammography must conclude with a final assessment from 1-6. Category 1: Negative - Breasts are normal. Strictly speaking, if a findign is mentioned in the body of the report, then the final assessment should not be a BI-RADS 1, no matter how benign the finding. Practically speaking, there is no management difference between BI-RADS 1 and 2, and often an insiginificant finding(such as a past biopsy clip, breast implants, or some clearly benign calcifications) would not disqualify a report from being BI-RADS 1. Category 2: Benign finding(s) - A finding that is mentioned in the impression but that is definitely benign should technically be BI-RADS 2. No additional workup or follow-up is needed. Category 3: Probably benign finding - short interval follow-up recommended - A finding in BI-RADS 3 should have \<2% risk of malignancy. It is necessary to conduct a complete diagnostic imaging evaluation using diagnostic views (e.g., spot compression magnification, etc.) and/or ultrasound before assigning a probably benign (Category 3) assessment. Category 3 is never appropriate for screening mammography. According to the 4th Edition of BI-RADS (2003), Category 3 is not for palpable lesions. However, more recent data suggest that is is acceptable to assign appropriate palpable lesions as BI-RADS 3 after a full imaging workup. Action required: Short interval follow-up, typically 6 months. In general, if a benign appearing lesion demonstrates 2 years of stability it can be considered benign (BI-RADS 2). Any interval change is suspicious and may warrant biopsy. Category 4: Suspicious abnormality - biopsy recommended - Findings are suspicious for maligancy, with a probability of being malignant \>2% and \<95%. Category 4 can be subdivided into Category 4A, 4B, and 4C, with 4A being least suspicious, and 4C being most suspious. All recommendatiosn for breast interventional procedures must be at least BI-RADS 4, including cyst or abscess aspiration. Action required: Biopsy or aspiration. Category 5: Highly suggestive of malignancy - biopsy or direct surgical treatment recommended. These lesions have a high probability (\>95%) of being cancer. A lesion that a radiologist describes as "I'll eat my hat if that's not cancer!" should be classified as BI-RADS 5. The prototypical BI-RADS 5 cancer would look like a spiculated mass with fine pleomorphic/linear-branching calcifications. Action required: Biopsy or surgery. Category 6: Known biopsy - proven malignancy - appropriate action should be taken. This category is reserved for lesions identified on the imaging study with prior biopsy proof of malignancy. Typically, a plan of action is already in place.

Answer 2

In every mammographic report, the mammographic patter of fibroglandular density should be characterized into one of the above quartiles. Women with dense fibroglandular tissue have an increased risk of developing breast cancer, and detection of early cancer can be obscured by the fibroglandular tissue. A woman with extremely dense breasts has a 5x relative risk of breast cancer compared to a woman with almost entrirely fatty breasts. Bilateral interval increase in fibroglandular density is usually benign and may be caused either by hormonal effects or breast edema. A unilateral increase in fibroglandular density is worrisome for lymphatic obstruction, which may be malignant. Edema due ot systemic causes, such as congestive heart failure, typically causes bilateral trabecular blurring and skin thickening. Hormone therapy may cause an increase in fibroglandular density, without skin thickening. Proliferation of cysts and fibrocystic change can be seen, even in postmenopausal women. Pregnancy, lactation, and weight loss may all cause an interval increase in fibroglandular density.

Answer 3

Unilateral skin thickening can be due to either benign or malignant causes. Similar to changes in fibroglandular density, bilateral skin thickening is usually benign and the result of a systemic process. Benign causes - Radiation therapy (usually unilateral). Acute mastsitis (usually unilateral). CHF (fluid overload), renal failure (fluid overload due to protein wasting), and liver failure (fluid overload due to hypoalbuminemia) may all produce unilateral or bilateral skin thickening. Malignant causes - Inflammatory carcinoma, which represents invasion of dermal lymphatics by cancer. A mammographic mass may be present. Locally advanced carcinoma. Lymphatic obstruction from axillary adenopathy.

Answer 4

A mammographic mass is a space-occupying lesion with convex borders seen in two different projections. In contrast, an asymmetry is seen in one view only.

Answer 5

Careful evaluation of the margins of a mammographic mass at the interface with surrouding tissue is key to stratifying the suspicion for malignancy. Circumscribed: At least 75% of the margin must be well-defined, while the remainder may be obscured with overlying tissue. In general, unless a mass is new, a circumscribed mass is benign and a non-circumscribed mass is suspicious. Of course, there are exceptions to this (abscesses can appear malignant and some indolent cancers in elderly women can appear benign). Microlobulated: A microlobulated mass has a finely irregular or serrated edge. Obscured: A margin is obscured if it is greater than 25% hidden by superimposed or adjacent normal tissue. The term obscured implies that the radiologist believes that the mass may be circumscribed, but the margin is hidden by overlying tissue. Indistinct: A poorly defined margin (or portion of the margin) raises concern that the lesion may be infiltrating. Spiculated: Linear densities radiate from a mass. A spiculated mass is malignant until proven otherwise.

Answer 6

Most breast cancers that form a visible mass are of equal or higher density than the surrounding fibroglandular tissue. Cancers never contain fat, although theoretically it's possible for a breast cancer to engulf a bening fat-containing lesion. The BI-RADS lexicon for density includes a radiolucent (fat density), low density, equal density, and high density. A circumscribed radiolucent mass is benign.

Answer 7

The BI-RADS lexicon for shape includes round, oval, lobular (undulating contour), and irregular. Although malignancy may be any form, an irregular mass is most suspicious for malignancy.

Answer 8

The four quadrants of each brest are: Upper outer quadrant, upper inner quadrant, lower outer quadrant, and lower inner quadrant. When referring to the opposite breast, the mirror opposite quadrant is the contralateral quadrant with the same name. For instance the upper outer quadrant of the left breast is the mirror opposite qudrant of the upper outer quadrant of the right breast. If subareolar or axillary tail are used to localize a lesion, then it is not necessary to specify a quadrant. Although clockface is used for ultrasound location, quadrant is preferred for mammography.

Answer 9

Architectural distortion represents linear densities emanating from a central point, without a definite mass visible. Architectural distortion is caused by tethering of the normal fibroglandular tissue and is highly concerning for a cancer, although there are some benign causes. If there is no history of surgery or trauma, biopsy is appropriate. Microcalcifications may be associated with malignant ductal calcification. Skin retraction is most commonly postsurgical but may represent desmoplastic tumor reaction. Nipple retraction is tethering or angulation of the nipple. Retraction should not be confused with inversion (where the whole nipple points inwards). Nipple inversion may be developmental, bilateral, and is not necessarily a sign of malignancy if stable. Skin thickening may represent edema or be secondary to prior radiation therapy. Trabecular thickening represents thickening of the fibrous septa of the breast, which can be seen in edema or in patients who have received radiation therapy. Axillary adenopathy may be normal or suspicious, depending on the morphology of the lymph nodes. Although it is normal for a few nodes to be present in the axilla, nodes with replacement of the normal fatty hilum may warrant evaluation, especially if new.

Answer 10

Most mammograms will show calcifications, which are overwhelmingly likely to be benign. However, careful analysis of breast calcifications is essential. Abnormal calcification may be the earliest, and possibly the only, mammographic manifestation of cancer. Certain types of calcifications can be definitively characterized as benign,while some are highly suspicous for malignancy. Other morphologies are indeterminate. It is almost always necessary to perform spot compression magnification to characterize calcification as either indeterminate or suspicious for malignancy. In contrast, most types of benign calcification can be described on routine full-field views (an exception would be milk of calcium calcifications, which generally require a true lateral view with magnification). Magnification employs air-gap technique and a small (0.1 mm) focal spot.

Answer 11

Skin calcifications are associated with sweat glands, are usually punctate or lucent-centered, and are most common medially, where the concentration of sweat glands is higher. Skin calcifications in a small cluster may project over teh breast and resemble suspicious calcifications. If skin calcifications are suspected, a tangenital view should be performed. To perform a tangenital view, the calcifications should be imaged using the alphanumeric needle localization grid. A BB is then placed over the calcifications as guided by the grid, and then the BB is imaged in tangent. On the tangenital view, skin calcifications should be seen in the dermis immediately deep to the BB marker.

Answer 12

Arterial vascular calcifications within the breast have a distinctive morphology and are typically not mentioned in the body of the report unless they are very extensive or the patient is very young. Early or incomplete vascular calcifications may pose a potential problem as they may appear similar to fine linear calcifications, which are suspicious.

Answer 13

"Popcorn" calcifications are caused by an involuting or hyalinizing fibroadenoma. Not all fibroadenomas calcify. However, when calcification does occur, it starts as peripheral calcification and progresses to the classic chunky popcorn-like appearance. At an early stage, the small calcifications of a fibroadenoma may resemble those of cancer adn prompt biopsy; however, a benign fibroadenoma can be diagnosed with confidence when the calcifiations have the typical popcorn morphology.

Answer 14

Milk of calcium represents free-floating calcium in tiny benign cysts. The most important feature of these calcifications is the apparent change in shape of the calcium particles between the CC and lateral projections. On the CC view the calcifications are often indistinct and appear as fuzzy, round, amoprhous deposits. On the 90 degree lateral, they are more clearly defined, semilunar or crescent-shaped in moprhology due to dependent layering.

Answer 15

Sutural calcifications represent calcium deposited on suture material, usually after radiation therapy. Sutural calcifications are uncommonly seen due to changes in modern surgical technique.

Answer 16

Dystrophic calcifications may occur as a sequela of surgery, biopsy, trauma, or irradiation. Usually the appearance of dystrophic calcification is distinctive, but may pose a diagnostic challenge when new or evolving.

Answer 17

Round calcifications are due to various etiologies and are benign.

Answer 18

Punctate calcifications are round and smaller than 0.5 mm. Even though these are considered benign, an isolated cluster of punctate calcifications may warrant close surveillance or even biopsy is new or ipsilateral to a cancer.

Answer 19

Benign, smooth calcifications with a lucent center can range in size from less than 1 mm to greater than 1 cm in diameter.

Answer 20

Fine peripheral calcification represents calcium deposited on the surface of a sphere, usually occuring in an area of fat necrosis or a cyst with calcified walls.

Answer 21

Amorphous calcifications are too small or hazy to ascertain the detailed morphologic appearance. Diffuse scattered amorphous calcifications are usually benign, although magnification views are important to rule out any suspicious clusters. Amorphous calcifications in a clustered, regional, linear, or segmental distribution are more suspicious and warrant biopsy.

Answer 22

Coarse heterogenous calcifications are irregular calcifications that are generally larger than 0.5 mm, but smaller than dystrophic calcifications. Evolving dystrophic calcifications or early calcifications associated with hyalinizing fibroadenomas or fat necrosis may appear as coarse heterogenous and pose a diagnostic challenge. Coarse heterogenous calcifications may be associated with malignancy and biopsy is often warranted, especially when new.

Answer 23

By definition, fine pleomorphic calcifications vary in shape and size, producing a characteristic dot-dash appearance. Fine pleomorphic calcifications vary in shape and size, producing a characteristic dot-dash appearance. Fine pleomorphic calcifiations are highly suspicious for malignancy, most commonly seen in DCIS or invasive ductal carcinoma. When evaluating any group or cluster of calcifications, one should always ask, "can these be pleomorphic?" If so, biopsy should be obtained.

Answer 24

Fine linear and fine-linear branching calcifications are similarly highly suspicious for malignancy. The branching distribution suggests filling of the lumen of a duct system involved by DCIS.

Answer 25

The distribution of calcification can greatly affect the suspicion of malignancy. Although diffuse/scattered adn regional calcifications are usually considered benign, the morphology of the calcifications in question is also important. A diffuse/scattered or regional distribution of suspicious fine pleomorphic or fine-linear branching calcifiations may represent multicentric cancer. Similarly, a more suspicious distribution (linear, grouped/clustered, or segmental) of calcifications with a typically benign morphology may warrant further workup.

Answer 26

Diffuse or scattered calcifications are distributed randomly throughout the breast. Punctate and amorphous calcifications in a diffuse or scattered distribution are usually benign and often bilateral, typically associated with fibrocystic change or sclerosing adenosis.

Answer 27

Regional calcifications are distributed in a large volume (\>2 cc) of breast tissue not conforming to a ductal distribution. Since this distribution may involve most of a quadrant or more than a single qudrant, malignancy is less likely.

Answer 28

Linear calcifications are arrayed in a line. Linear distribution of calcifications elevates suspicion for malignancy as this suggests calcium deposits within a duct.

Answer 29

Segmental calcifications suggest calcium deposited in a ductal system, which is worrisome. When the morphology is clearly secretory (rod-like), a segmental distribution can be benign. When intermediate-suspicion (such as amorphous) or typically benign (such as round or punctate) calcifications are seen in a segmental distribution, concern should be raised for malignancy.

Answer 30

A cluster is defined as at least five small calcifications in \<1 cc of tissue. Grouped or clustered calcifications rasise suspicion for malignancy. The use of the word clustered should be reserved for more suspicious calcifications that will be biopsied. The slighly less worrisome grouped descriptor is generally used for calcifications that may be able to be followed as BI-RADS 3 rather than immediately biopsied.

Answer 31

Spot compression is compression of a focal region of the breast, which allows for better compression and therefore better resolution. Spot compression is almost always the next step in evaluating a focal suspicious mammographic abnormality. Typically, for evaluation of calcifications, spot compression magnification is used. For evaluation of a mass or asymmetry, magnification is usually not needed. Note that areas of architectural distortion may actually appear less apparent on magnification views. Almost all cancers are associated with parenchymal fibrosis due to a desmoplastic reaction. If an apparent asymmetry "presses out" with focal compression, then the apparent abnormality can be presumed to represent superimposed normal pliable fibroglandular tissue. If the abnormality does not significantly change shape when compressed, then it is suspicious and spot compression allows the best chacterization of its margins. Further evaluation is warranted, typically with ultrasound. A smaller compression device will allow more precise compression, with the downside of possibly losing landmarks.

Answer 32

The lateral XCC (XCCL) pulls lateral breast tissue into the detector. The medial XCC (XCCM) pulls medial breast tissue into the detector.

Answer 33

Rolled views are obtained by moving the top and bottom of the breast in opposite directions. Rolled views are helpful to localize a lesion that is seen on the CC view only. Two rolled views are typically obtained. A view is obtained with the top of the breast rolled medially (RCCM) and a second view with the top rolled laterally (RCCL). If a lesion moves medially with the RCCM view, tehn it's in the superior breast. If a lesion moves laterally with an RCCM view, then it's in teh inferior breast. The lateral view can also be rolled, although this is less commonly performed.

Answer 34

Images with reduced compression can be obtained to image far posterior lesions that may "slip out" of the detector when full compression is applied.

Answer 35

A true lateral can be obtained in an ML (most commonly) or LM projection. In an ML view, the X-rays first travel through the medial breast, with the detector placed laterally. Conversely, the detector is medial in an LM projection. It is ideal to place the lesion in question closer to the detector if possible. For example, a medial lesion is best imaged on an LM projection. The true lateral is used to diagnose milk of calcium. In addition, to spot compression magnification, magnification spot views should also be obtained in the true lateral projection when milk of calcium is suspected. In the true lateral view, the precipitated calcium sinks to the bottom of the small cysts, where it is seen mammographically as tiny crescents (versus the fuzzy round appearance of the CC view). The true lateral view is helpful to triangulate a lesion seen on MLO view but not CC. The true lateral view can be helpful for planning a stereotactic procedure.

Answer 36

A true lateral view is helpful to triangulate a lesion seen only on MLO view. If the lesion rises on the lateral compared to the MLO, the lesion is located in the medial breast (medial: muffins rise); if the lesion sinks, it is lateral (lateral: lead sinks)

Answer 37

A screening mammography can only receive the BI-RADS 1,2, or 0 assessments. If screening mammogram findings are concerning, the patient is assessed as BI-RADS 0 and is recalled for additional evaluation. When the patient returns for the diagnostic workup, spot compression views of the area in question should be obtained. If spot compression shows only normal pliable fibroglandular tissue, then no further workup is needed (BI-RADS 1). If an asymmetry persists on spot compression then it needs to be localized on two orthogonal views. When correlating a lesion on two views, it is important to remember that the lesion should be located at approximately the same distance (within 1 cm) from the nipple on each view. This rule may prevent mistaken localization of different lesions on each projection. If the lesion is seen only on the MLO, a lateral view should be subsequently obtained to triangulate the lesion as described above. A lesion seen on the MLO view but not the CC view may be located far laterally. An exaggerated CC lateral (XCCL) view can better image the far lateral tissue. Rolled CC views may also help to visualize the lesion. A lesion seen only on the CC may be in the upper-inner quadrant and not included in the MLO view. Rolled views are typically performed to localize lesions seen only in the CC view. Once a lesion is localized to a quadrant, targeted ultrasound should be performed. If a suspicious single-view finding still cannot be localized despite a thorough mammographic and ultrasound evaluation, MRI can be helpful as a problem-solving tool. Mammographic stereotactic biopsy is also an option to biopsy a one-view findign (although stereotactic biopsy is used much more commonly to biopsy calcifications). In general, biopsy should be performed for a mass with any suspicious feature either on ultrasound or mammography. For instance, a well-circumscribed mammographic mass that has an irregular border on ultrasound is suspicious depsite its mammographic appearance. Most new findings are suspicious, with a notable exception being a well-circumscribed mammographic mass shown definitively to be a simple cyst on ultrasound. Two years of stability is generally considered adequate to call a benign-appearing mass benign.

Answer 38

The mammographic workup for a palpable abnormalit is similar ot that of an asymptomatic lesion found on mammography, with one key difference: In general, all palpable findings are evaluated by ultrasound, even if the mammogram is negative.

Answer 39

There are data to support the assignment of BI-RADS 3 in the following three situations, which are not definitively benign but have been shown to have less than 2% the risk of cancer. Circumscribed, benign-appearing solid mass - A probably benign solid mass must have a benign mammographic appearance. Its shape must be round, oval, or lobulated, and its margins must be circumscribed. The mass must also lack any suspicious microcalcifications. Any new mass should also undergo ultrasound evaluation. If the ultrasound findings are also benign, that mass may be assigned BI-RADS 3 (or BI-RADS 2 if the ultrasound showed a simple cyst). A probably benign solid mass that has demonstrated at least two years of stability can usualy be considered benign (BI-RADS 2). Cluster of tiny round calcifications - The two BI-RADS descriptive terms for round calcifications (which are usually benign) are punctate (\<0.5 mm in size) and round (\>0.5 mm in size). It is usually necessary to use spot-compression magnification veiws to accurately characterize calcifications. Punctate or round calcifications in a cluster (\>5 calcifications/cc) can be diagnosed as probably benign (BI-RADS 3). Note that the morphology must be clearly punctate or round, and the distribution must be in a cluster. For instance, a cluster of amorphous calcifications is indeterminate and usually warrant biopsy. Similarly, although rare, punctate or round calcifications in a linear or segmental distribution would be suspicious. Some authors advocate using grouped as the BI-RADS distribution descriptor for calcifications that are followed as a BI-RADS 3 and clustered for calcifications that should be biopsied. Focal asymmetry - A focal asymmetry is a non-palpable lesion seen on two projections. Unlike a mass, a focal asymmetry does not have outwardly convex margins, and usually is interspersed with fat. Assuming no ultrasound correlate is seen, a focal asymmetry can be assessed as probably benign (BI-RADS 3) after a thorough workup. In contrast, a developing asymmetry is a focal asymmetry that has increased in size. It is suspicious and require further workup.

Answer 40

The subcutaneous (premammary) zone of the breast contains skin and dermis, subcutaneous fat, and some suspensory Cooper's ligaments. the subcutaenous zone is the site of skin lesions, including benign skin cysts. Dermal lesions are almost always benign and include epidermal inclusion cysts and sebaceous cysts. Epidermal inclusion cysts arise from a hair follicle and are filled with keratinous debris. On ultrasound imaging, an epidermal inclusion cyst appears as a circumscribed lesion with variable internal echotexture ranging from anechoic to heterogenous, depending on the amount of internal keratinous debris. Sebaceous cysts are indistinguishable from epidermal inclusion cysts on clinical and imaging findings. Sebaceous cysts arise form the outer sheath of the hair follicle. A lesion can be confidently diagnosed as a benign epidermal inclusion cyst or sebaceous cyst when it is located completely within the echogenic dermis. In contrast, lesions arising from the hypodermis (subcutaneous fat) can include a broader range of pathologies, including papilloma, fibroadenoma, and breast cancer. It is therefore critical to identify the anatomic site of orign as best as possible. Superficial breast lesions that are not entirely within the dermis can pose a diagnostic challenge, as the differential would include a possibly malignant hypodermal lesion. Two clues can be helpful to establish dermal origin: 1) visualization of a claw of dermal tissue wrapping around the lesion. 2) Visualization of a tract connecting the lesion to the epidermal skin surface.

Answer 41

The mammary zone is the site of most breast pathology, and includes ducts and terminal ductal lobular untes (TDLUs), fat, fibrous tissue, adn Cooper's ligaments.

Answer 42

The retromammary zone is just superficial to pectoralis and contains fat and a few Cooper's ligaments.

Answer 43

Parenchymal breast fat is hypoechoic, unlike ultrasound imaging of fat elsewhere in the body. In the contrast, fat in a lymph node hilum, fat in a lipoma, and fat necrosis may all appear hyperechoic.

Answer 44

The BI-RADS lexicon for the shape of an ultrasound mass includes oval, round, and irregular. Unlike the mammographic lexicon, lobular is not in the ultrasound lexcion for shape.

Answer 45

The orientation of the long axis of a mass (relative to the skin) is unique to ultrasound. A mass that is parallel in orientation is mroe likely to be benign. In contrast, a non-parallel mass (known informally as "taller-than-wide") is oriented with the long axis vertical and is suspicous for malignancy. This finding is based on the propensity of a malignant process to violate tissue planes.

Answer 46

Similar to mammography, benign masses are typically circumscribed. If the margins of a mass are not circumscribed, they can be characterized as indistinct, angular, microlobulated, or spiculated. Indistinct: No clear boundary between the mass and its surrounding tissue. Angular: Featuring sharp corners. Microlobulated: Serrated appearance of the margins. Spiculated: Linear projections emanating from the mass.

Answer 47

The internal echo pattern describes the internal texture of an ultrasound lesion. The two types of discrete ultrasound lesions are solid masses and cysts. A cyst can be a simple cyst, a complicated cyst, or a complex mass, which are discussed in detail later. The internal echo pattern helps to differentiate between cystic and solid lesions, An anechoic structure has no internal echoes and most commonly (but not always) represents a simple cyst. A hypoechoic structure is characterized by low-level internal echoes, wuch as seen in a complicated cyst or fibroadenoma. An isoechoic structure has the same echogenicity as surrounding fat per the BI-RADS definition, although some authors propose that an isoechoic structure is defined as relative to surrounding breast tissue. An isoechoic lesion can be challenging to visualize. A hyperechoic structure is more echogenic than fat. It may be either equal or greater in echogenicity compared to fibroglandular tissue. A complex echo pattern represents a combination of internal echogenicities, such as seen in a complex mass or necrotic tumor.

Answer 48

The lesion boundary describes the transition between the mass and the surrounding tissue. An abrupt interface is a clean demarcation between the lesion and surrounding tissue. An echogenic halo is an echogenic transition zone, which can be seen in cancer or abscess.

Answer 49

The posterior acoustic features of a lesion describe teh attenuation characteristics of the sound beam deep to the lesion. Acoustic enhancement (also called posterior through transmission) refers to a column of increased echogenicity posterior (deep) to the mass. Posterior enhancement is one of the characteristics of a simple cyst, although on its own posterior enhancement is not specific. Shadowing is attenuation of the sound beam as it passes through the lesion. Shadowing is associated with fibrosis, such as from a neoplastic desmoplastic reaction or a surgical scar. If a lesion has no posterior acoustic features, then the echogenicity of the area immediately deep to the mass is the same as adjacent tissue. A lesion can also have a combined pattern of posterior acoustic features, such as a fibroadenoma containing a large, coarse, shadowing calcification.

Answer 50

Lack of any malignant findings: If even a single malignant feature is present then a lesion is indeterminate or suspicious and should be biopsied. Marked hyperechogenicity (relative to fat). Circumscribed margins. Parallel orientation to the skin (wider-than-tall; width:height \>1.4) Ellipsoid shape. Few gentle macrolobulations. Thin echogenic pseudocapsule.

Answer 51

Spiculated margins, which is the most specific sign of malignancy. Non-parallel (taller-than-wide) orientation, the second most specific sign. Angular or microlobulated margins. Posterior shadowing. Markedly hypoechoic echotexture. Associated calcifications (visible on sonography as echogenic foci). Lesion boundary with wide zone of transition.

Answer 52

The following features are not helpful in differentiating between benign and malignant masses: Lesion size, iso- or mild hypoechogenicity, posterior acoustic enhancement, and heterogenous or homogenous texture.

Answer 53

There are data to support classification of the following lesions into the BI-RADS 3 (probably benign) category, with less than 2% risk of cancer: Complicated cyst or clustered microcysts. Oval, hypoechoic, circumscribed, parallel mass (consistent with fibroadenoma).

Answer 54

A lipoma is a benign lesion composed of mature adipocytes. A lipoma may present clinically as a palpable mass when the normal breast is displaced. A lipoma is a benign diagnosis that can be made entirely by mammography, where a lipoma will be seen as a radiolucent mass that may have a thin discrete rim. In contrast to an oil cyst, a lipoma will not have peripheral calcification. Ultrasound is not typically used in the evaluation of a suspected lipoma; however, ultrasound of a lipoma would show a circumscribed oval mass isoechoic to fat.

Answer 55

An oil cyst is one possible sequela of fat necrosis and can occur post trauma or surgery. Fat necrosis can have many imaging appearances, most commonly dystrophic calcification. The formation of an oil cyst following fat necrosis is less common but has a very distinctive appearance. When an oil cyst forms after fat necrosis, fat saponification leads to a circumscribed lucent lesion that can peripherally calcify. Ultrasound is not ideal for further evaluation, because fat necrosis can have a variable appearance on ultrasound.

Answer 56

Like purely fatty masses, all fat-containing circumscribed masses are benign (BI-RADS 2).

Answer 57

A hamartoma, also known as a fibroadenolipoma, is a benign mass containing fat and glandular tissue elements. The classic mammographic appearance of a hamartoma is a "breast within a breast", which displaces normal breast tissue. A pseudocapsule is typically seen surrouding the hamartoma. Mammography is almost always diagnostic. Ultrasound is typically not indicated but would show normal fibroglandular tissue and fat. Because fibroglandular elements are present within a hamartoma, it is possible (but rare) for breast cancer to occur within a hamartoma. Any suspicious mass or calcifications within the hamartoma should be worked up.

Answer 58

A galactocele is a cystic collection of milk that can present as a palpable mass in a lactating woman. On mammography, a galactocele appears as a well-circumscribed, macrolobulated mass containing mixed high density and fat. The classic mammographic finding (although uncommonly seen) is a fat/fluid level seen on the true lateral view. On ultrasound, a galactocele typically appears as a cyst-like mass. If aspiration is performed, the cyst fluid would be milky.

Answer 59

An intramammary lymph node is benign. The vast majority of intrammmary lymph nodes occur laterally, typically in the upper outer quadrant adjacent to a vessel. A lesion that appears like an intramammary lymph node but is in the medial breast should be carefully evaluated and should be considered suspicious until proven otherwise. On mammography, an intramammary lymph node should have a characteristic reniform shape with a fatty hilum (a lucent notch in the middle). If the hilum is not visible, a full workup should be performed including spot compression and/or ultrasound. Typically, a normal intramammary lymph node with a fatty hilum can be diagnosed with confidence on mammography, but ultrasound can be useful as a problem solving tool. Ultrasound will show a hypoechoic mass with central echogenicity that represents a fatty hilum. Color Doppler imaging would show vessels coming into the hilum. Note that while normal intramammary lymph nodes are only sometimes seen with the breast, there are almost always lymph nodes present in the axillar. If there is unilateral axillary lymph node enlargement and/or abnormal morphology, concern should be raised for ipsilateral breast cancer. Bilateral enlarged axillary lymph nodes are unlikely to be caused by breast cancer and may be due to systemic inflammatory or neoplastic disease, such as chronic lymphocytic leukemia or lymphoma.

Answer 60

Fibroadenoma is a benign neoplasm seen in young women and is the most common palpable mass in this age group. Clinically, a fibroadenoma will present as a firm, mobile mass. The classic mammographic appearance of a fibroadenoma is an oval or lobular equal density circumscribed mass, although this imaging appearance is nonspecific. A hyalinizing fibroadenoma, typically seen in older women, has a definitively benign mammographic appearance containing coarse "popcorn" calcification. The typical ultrasound appearance of a fibroadenoma is an oval, circumscribed mass with homogenous hypoechoic echotexture. Occasionally, a histologically benign fibroadenoma may have suspicious features on ultrasound including irregular borders, heterogenous internal echotexture, or shadowing, prompting biopsy in these cases. A fibroadenoma is benign, but these are often either followed (BI-RADS 3) or biopsied (BI-RADS 4), depending on the imaging characteristics or clinical context. If the following ultrasound features are met, the presumed fibroadenoma can be classified as BI-RADS 3, with a false negative rate of 0.5%. Ovoid shape, parallel orientation with a width to height ratio of \>1.4 (wider-than-tall). All margins circumscribed. Not highly hypoechoic. Variants of fibroadenoma include complex fibroadenoma, juvenile fibroadenoma, and giant fibroadenoma. A complex fibroadenoma contains proliferative elements and internal cysts, and confers a slightly increased risk of breast cancer. A juvenile fibroadenoma is seen in adolescents and is characterized by very rapid growth. A giant fibroadenoma is a fibroadenoma greater than 8 cm in size. Fibroadenoma may appear identical to a phyllodes tumor, especially when larger.

Answer 61

A papilloma is a benign tumor of lactiferous ducts, usually seen in women between age 30 and 50. Papilloma is the most common cause of pathologic (bloody, serous, or serosanguinous) nipple discharge. Papilloma grows on a fibrovascular stalk and torsion of the stalk can cause pain and bleeding. Note that DCIS may also present with bloody nipple discharge. The typical mammographic appearance of a papilloma is a round or oval, circumscribed or irregular mass, usually located in the subareolar region. Although uncommonly performed today, galactography shows an intraductal filling defect. On ultrasound, a papilloma appears as a solid round or oval mass. When causing nipple discharge, the papilloma may be evident as a mass in a fluid-filled duct. Once biopsied, papillomas are typically treated with surgical excision as papilary carcinoma may appear identical on imaging, especially when atypica is seen histologically.

Answer 62

Pseudoangiomatous stromal hyperplasia (PASH) is a rare entity of unknown etiology composed of stromal and epithelial proliferation, thought to be under hormona control. On mammography, PASH appears as an ill-defined, round or oval mass. Occasionally it may be circumscribed. Ultrasound shows a hypoechoic or mixed echogenicity, oval or irregular mass. Pathologically, PASH may mimic a low-grade angiosarcoma, so excisional biopsy is usually performed if a mass diagnosed as PASH shows interval growth.

Answer 63

It is uncommon for breast carcinoma to be circumscribed, but a new circumscribed mass must prompt suspicion, especially in a postmenopasual woman. In particular, medullary and mucinous carcinoma are histologic subtypes of breast cancer that can present as a circumscribed round mass on mammography and as a hypoechoic mass on ultrasound. These cancers can be so hypoechoic that they may mimic a benign cyst at first glance. In contrast to a cyst, however, internal vascularity is often present.

Answer 64

A giant fibroadenoma is simply a large fibroadenoma \>8 cm in size. A giant fibroadenoma has a similar appearance to fibroadenoma excepting its larger size. A juvenile fibroadenoma is a rapidly growing fibroadenoma variant seen in adolescents, which may become giant.

Answer 65

A phyllodes tumor (previously called cystosarcoma phyllodes) is a rare, rapidly growing tumor that is typically large when first detected. Phyllodes tumors occur in an older population compared to fibroadenomas, typically in women age 40-50. The majority of phyllodes tumors are benign, although approximately 25% are malignant, and 20% of those may metastasize. Since imaging cannot distinguish between benign and malignant phyllodes, treatment is wide surgical excision. Incomplete excision leads to recurrence. The typical mammographic appearance of phyllodes tumor is a large, oval or lobular, circumscribed mass. On ultrasound, phyllodes tumor appears as a smoothly marginated mass with heterogenous internal echotexture. The imaging differential of such a mass includes a large firoadenoma or cancer.

Answer 66

Lactational adenomas are seen in the second or third trimester of pregnancy or the postpartum period. Patients present with a freely mobile mass, which may be tender if it has rapidly enlarged. A lactational adenoma is benign and does not need excision after biopsy. It regresses when the patient is no longer lactating.

Answer 67

Multiple intraductal papillomas tend to occur in younger patients compared to solitary papillomas. When multiple, papillomas tend to be more periopheral in location and bilateral. In contrast to solitary papillomas, multiple papillomas are infrequently associated with pathologic nipple discharge. Multiple intraductal papillomas confer an increased risk of breast cancer. The mammographic appearance of multiple papilomas is of multiple well-circumscribed masses located in the peripheral breast. Two similarly named entities have potentially confusing terminology. Papillomatosis is a term that is frequently mistaken with multiple intraductal papillomas. Papillomatosis represents microscopic foci of intraductal hyperplasia with a papillary architecture. It is a pathologic diagnosis rather than an imaging finding. Juvenile papillomatosis is a rare cause of a mass that resembles a fibroadenoma in adolescent younger women up to age 40.

Answer 68

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous disease that features pigmentary changes (e.g. cafe au lait spots and Lisch nodules) and neurofibromas. Cutaneous neurofibromas are the hallmarks of NF1, thought to arise from small nerve tributaries of the skin. On mammography, multiple cutaneous neurofibromas may appear as multiple skin masses outlined by air.

Answer 69

Steatocystoma multiplex is a rare, autosomal dominant disease of multiple intradermal oil cysts. When the skin over the breasts is involved, mammography shows innumerable fat-density masses.

Answer 70

A simple cyst is a benign, fluid filled structure that is round, oval, or gently lobulated in shape, with circumscribed margins and anechoic internal echo pattern. A cyst features an imperceptibly thin wall and posterior through transmission (posterior enhancement). A cyst meets all the above criteria is benign and can be classified as BI-RADS 2. A simple cyst causing pain or discomfort may be aspirated.

Answer 71

A complicated cyst is a cyst that contains low-level internal echoes or layering debris. A complicated cyst is considered benign, although the risk of malignancy is not negligible. When new, complicated cysts are typically either classified as probably benign (BI-RADS 3) or aspirated. If the aspirated fluid is white, clear, or yellow, the fluid is presumed to be benign and discarded. Bloody fluid is sent for cytology. Occasionally, a complicated cyst can appear identical to a solid mass with homogenous internal echoes. In such a case, core biopsy is typically performed.

Answer 72

The BI-RADS term complex mass describes a cyst with any complex feature, including thick walls or septations, or any solid or nodular element. A complex mass is a suspicious BI-RADS 4 lesion that should be biopsied. The solid component should be targeted with a core needle and a post-biopsy tissue marker should be placed. 36% of complex masses will be cancer upon biopsy. Malignancies that may appear as a complex mass includes intracystic carcinoma, intracystic papilloma, cystic phyllodes tumor, and a solid cancer with central necrosis. Intracystic carcinoma is an uncommon presentation of breast cancer, defined as cancer arising from the walls of a cyst. The typical ultrasound appearance of an intracystic carcinoma is a solid mural nodule projecting into the cyst fluid. Benign causes of a complex mass include hematoma, abscess, fat necrosis, galactocele, and benign cyst with adherent debris.

Answer 73

Thought to be due to apocrine metaplasia or fibrocystic change, clustered microcysts are composed of several adjacent tiny 2-5 mm cystic spaces separated by thin (\<0.5 mm) septae. Clustered microcysts are a special class of benign cystic lesion. They can be classified as BI-RADS 2 if clearly seen and nonpalpable. Clustered microcysts may eventually evolve into a simple benign cyst

Answer 74

Invasive ductal carcinoma (IDC) is the most common form of breast cancer. A typical mammographic appearance of IDC is a high density, spiculated mass. Malignant-type (pleomorphic or fine linear branching) calcifications are often present within the mass. It is important to remember that IDC can have a variable imaging appearance and may also present as a round mass, as isolated calcification, as architectural distortion, or any combination of these findings.

Answer 75

Invasive lobular carcinoma represents approximately 10% of all breast cancer and can be challenging to diagnose, with a false-negative mammography rate as high as 21%. Invasive lobular carcinoma tends to spread in an infiltrating pattern surrounding the glandular tissue, thus making its detection by mammogram or physical exam often quite difficult. The imaging appearance of invasive lobular carcinoma is variable. Similar to invasive ductal carcinoma, invasive lobular carcinoma may present as a mass (with or without spiculation) or subtle architectural distortion (which may seen in one view only). In contrast to IDC, invasive lobular carcinoma rarely contains microcalcifications. Invasive lobular carcinoma is more often multifocal or bilateral compared to IDC.

Answer 76

Tubular carcinoma is a slow-growing cancer that typically presents as a small, spiculated mass. The imaging appearance may remain stable across several prior mammograms, which emphasizes the fact that a malignant-appearing finding must be fully evaluated even if stability is demonstrated. Prognosis of tubular carcinoma is more favorable compared to IDC NOS. It is thought that radial scar may be a precursor to tubular carcinoma.

Answer 77

A radial scar is a benign lesion of uncertain etiology that appears as a spiculated mass or architectural distortion. Despite the name, a radial scar has nothing to do with a post-traumatic or post-surgical scar. A complex sclerosing lesion is histologically identical but larger (\>1 cm); however, recent literature suggests that these two names describe the same entity. Histologically, a raidal scar is characterized by adenosis hyperplasia, and central atrophy resulting in pulling-in of adjacent tissue and formation of a spiculated mass and architectural distortion. The mammographic and ultrasound appearance of a radial scar may be identical to cancer, appearing as a spiculated mass or architectural distortion on mammography and a hypoechoic shadowing mass on ultrasound. Radial scar may be associated with tubular carcinoma and high-risk lesions such as atypical ductal hyperplasia and lobular carcinoma in situ. Treatment is surgical excision.

Answer 78

A postsurgical scar, either due to prior lumpectomy or excisional bioopsy, may be indistinguishable on mammography from cancer in the absence of clinical history. Additional postsurgical changes are often present to aid in the diagnosis, including volume loss in the treated breast and skin retraction. Additionally, unlike recurrent tumor, a postsurgical scar should not get larger over time. If the patient was treated with radiation therapy, dystrophic calcification and skin thickening/retraction may also be present.

Answer 79

Although usually apparent clinically, an abcess can appear as an irregular or spiculated mass.

Answer 80

Sclerosing adenosis and diabetic mastopathy are benign conditions that may mimic cancer on imaging. Sclerosing adenosis is a benign proliferative breast lesion caused by lobular hyperplasia. Fibrous tissue envelops and distorts the glandular elements, with resultant sclerosis of the affected tissue. Microcalcificatios may be present, which mammographically may be indistinguishable from malignancy. Diabetic mastopathy is a benign disorder seen in long-term insulin-dependent diabetics that clinically present as a large, painless, firm breast mass that may be indistinguishable from cancer. It is pathologically associated with inflammatory lymphocytes and fibrosis. Mammography shows an ill-defined mass or asymmetric density, which appears as a hypoechoic shadowing mass on ultrasound.

Answer 81

Unilaterally enlarged axillary lymph nodes are suspicious for breast cancer metastasis, although size alone is nonspecific for determining metastatic involvement. Sonographic features suspicious of lymph node metastasis include: Round shape, Thickened (\>3 mm) cortex. Eccentrically thickened cortex, Focal outwards cortical bulge, Hilar indentation or obliteration of the hilum by thickened cortex. Bilateral adenopathy is more likely to be due to a systemic process, including collagen vascular disease, lymphoma, and leukemia.

Answer 82

Lymphoma involving the breast can have a variable appearance. Usually, primary breast lymphoma is caused by diffuse large B-cell lymphoma. Most B-cel lmphomas affecting the breast present as a palpable mass. Axillary adenopathy may be present. On mammography, lymphoma may present as a mass with indistinct margins. On ultrasound, lymphoma typically appears as a hypoechoic mass. In contrast to epithelial cancers such as invasive ductal carcinoma, calcifications are rarely seen in breast lymphoma. In a patient with a known diagnosis of lymphoma and a new breast mass, the primary consideration remains breast cancer. Histologic sampling is essential as lymphoma is treated with chemoradiation, not surgery.

Answer 83

Angiosarcoma of the breast is a rare malignancy that may be primary or secondary prior breast conservation theraphy with radiation therapy. On MRI, angiosarcoma is hyperintense on T2-weighted images and demonstrates intense enhancement.

Answer 84

Hematogenous metastases to the breast have a variable appearance but are usually circumscribed round masses. Multiple new masses in a non-ductal distribution are especially worrisome for hematogenous metastases. Melanoma and renal cell carcinoma have a propensity to metastasize to the breast.

Answer 85

An asymmetry is a region of breast tissue that is prominent on one view only and most commonly represents superposition of glandular tissue.

Answer 86

Global asymmetry is an asymmetric amount or density of breast tissue involving the majority of one breast only, most commonly due to greater volume of parenchyma in one breast compared to the other. More than one quadrant must be involved. Although global asymmetry is usually a normal variant, when associated with a concerning finding such as a mass, architectural distortion, skin thickening, or any palpable abnormality, then further workup is warranted.

Answer 87

A focal asymmetry is an abnormality involving less than one quadrant seen on two views (in contrast to an asymmetry) but that does not meet the criteria for a mass. A mass will have distinct borders and convex contours, while a focal asymmetry will have concave contours. A focal asymmetry usually represents a prominent area of normal breast tissue, particularly when there is interspersed fat, but further evaluation may be warranted. After a complete workup (including additional mammographic views with spot compression and targeted ultrasound), a nonpalpable focal asymmetry has \<1% chance of being malignant and can be placed in BI-RADS 3. The lesion can be called benign after two years of stability.

Answer 88

Architectural distortion describes lines radiation from a central point with no centra mass visible, producing tethering and indentation of the breast tissue. Architectural distortion is suspicious for malignancy. The differential for architectural distortion is similar to the differential for a spiculated mass discussed previously.

Answer 89

The sternalis muscle is an accessory parasternal chest wall muscle present in less than 10% of patients. It is either triangular or rounded in shape and seen only on the CC view medially at far-posterior depth. It is more commonly unilateral. The main differential consideration is a medial mass; however, the characteristic shape and lack of corresponding finding on the lateral or MLO views is usually sufficient to diagnose a sternalis muscle. MRI can be performed in ambiguous cases.

Answer 90

An accessory nipple (polythelia) is seen in approximately 2% of neonates and may present on mammography as a rounded mass laong the mammary crest. Physical exam is diagnostic.

Answer 91

Poland syndrome is a congenital disorder characterized by unilatreal absence of the pectoralis major muscle, often associated with ipsilateral absence of breast tissue and syndactyly.

Answer 92

Accessory or ectopic breast tissue occurs most commonly in the axillary tail.

Answer 93

Breast MRI plays a complementary role to mammography int he evaluation of breast cancer. Contrast-enchanced breast MRI features excellent soft tissue contrast and high sensitivity for the detection of cancer. Although the distinction between normal or benign structures and malignancy is often not apparent using standard T1 and T2-weighted sequences, the addition of dynamic contrast enhancement greatly increases the accuracy for detection of malignancy. However, one of the greatest challenges facing the evolving field of breast MRI is the overlap in imaging findings between benign and malignant lesions. Both tumors and benign lesions may enhance and may exhibit similar morphologic characteristics. Strategies such as the characterization of enhancement kinetic curves and development of a stringent BI-RADS lexicon help to tackle this problem. One relative weakness of MRI compared to mammography is the lack of sensitivity to microcalcifications. While some larger calcifications can be detected as susceptibility artifact, mammography is superior to MRI for detection of small calcifications. In clinical use to evaluate for breast cancer, standard 1.5 Tesla breast MRI has been shown to have a negative predictive value of 98.9% and a relatively low false positive rate (49.7% positive predictive value for malignancy).

Answer 94

The risk stratification of an enhancing lesion involves separate evaluation of the lesion morphology (including morphologic description of the enhancement pattern) and teh kinetic pattern of enhancement. Thus, both high spatial and temporal resolution is required, which is achieved using modern MRI equipment and protocols. Breast MRI is performed with the patient prone using a dedicated breast coil. Imaging of both breasts should be performed unless the patient has had a previous mastectomy. Bilateral imaging is very helpful to distinguish background parenchymal enhancement from pathological enhancement. Both breasts are imaged simultaneously. Standard sequences include T1- and T2-weighted images, with and without fat saturation. The crux of the breast MRI exam is the pre- and post-contrast sequences, which are obtained using fat saturation. Dynamic enhanced images are obtained sequentially to evaluate for enhancement over time. Although protocols vary by institution, three-dimensional fat-suppressed high-resolution spoiled gradient-echo T1-weighted images are commonly used for both pre- and post-contrast imaging (GE: VIBRANT; Siemens: VIEWS; Phillips: BLISS). Intraductal fluid may be hyperintense on T1-weighted images, complicating the evaluation of enhancement. Post-processing is required to evaluate for true enhancement. The simplest form of post processing is subtraction, where the dynamic post-contrast images are subtracted from the initial T1-weighted fat-saturated images. The maximum-intensity projection (MIP) image is a useful post-processing tool based on the subtraction images. A MIP highlights the brightest pixel along each parallel ray to create a volumetric data set where the enhancement can easily be seen in three dimensional space. Computer-aided detection (CAD) is a helpful adjunct for analysis of contrast-enhanced MRI sequences. CAD allows creation of a color angiomap, where the colors correspond to different temporal patterns of enhancement. These temporal enhancement curves allow further characterization of a lesion to determine the level of suspicion for malignancy.

Answer 95

Tumor angiogenesis and resultant capillary permeability allows early detection of cancer by contrast-enhanced MRi. Because tumor-associated vessels are throught to be relatively large and leaky, quantification of enhancement kinetics would be expected to show rapid enhancement and washout. This principle is the foundation for kinetic analysis in dynamic contrast-enhanced breast MRI. Dynamic contrast-enhanced breast MRI repeatedly images the breast at multiple time points. Enhancement curves can be generated by plotting percent relative enhancement (compared to the unenhanced image) against time. The enhancement curve can be divided into early (within the first two minutes) and delayed phases. Per the BI-RADS lexicon, the kinetics of early enhancement can be characterized as slow, medium, and rapid. A malignant lesion would be expected to have rapid early enhancement. Analysis of the delayed phase of enhancement allows one to further stratify the risk of malignancy. The BI-RADS lexicon describes three kinetic patterns of delayed enhancement: Persistent (type I), plateau (type II), and washout (type III). A type I (persistent) curve shows continuously increasing (\>10%) enhancement in the delayed phase. Although a type I curve is associated with a benign finding in 83% of cases, up to 9% of malignant lesions may feature a type I curve. A type II (plateau) curve has an early rise in enhancement, but levels off (within 10%) in the delayed phase. A type II curve is suspicious, although less strongly so than a type III curve. Type II curves have been reported to have a positive predictive value between 64% and 77%. A type III (washout) curve has a \>10% dcrease in signal intensity in the delayed phase and is suspicious for malignancy. A type III curve has a positive predicitve value of 87-92%, but is seen in only 21% of malignant lesions. False positive benign lesions that may show washout kinetics include lymph nodes, adenosis, and papillomas. In the evaluation of a lesion, morphology is much more important than the pattern of enhancement. If a mass with malignant morphology (e.g., spiculated margins or rim enhancement) demonstrates type I enhancement, it remains just as suspicious for cancer. Similarly, a small, circumscribed, reniform mass adjacent to a vessel with type III kinetics is a typical appearance for a benign intramammary lymph node and should not be biopsied.

Answer 96

The MRI lexicon for mass shape is identical to that of mammography Round: Spherical in shape. Oval: Elliptical or oblong in shape. Lobular: Undulating or scalloped contour. Irregular: Uneven shape. An irregular shpae is suspicious for malignancy.

Answer 97

Evaluation of the margin of an enhancing mass is the most predictive MRI imaging feature. Similar to mammography, the BI-RADS lexicon for mass margin includes smooth, irregular, and spiculated. Smooth margins are more suggestive of benignity, while irregular or spiculated margins are more suspicious for malignancy. A mass with spiculated margins is thought to represent cancer 84-91% of the time. The shape and margin of a mass are best evaluated in the early post-contrast sequences. Progressive enhancement of the normal surrounding breast parenchyma on the subsequent post-contrast sequences may obscure the true margins of a mass.

Answer 98

Several descriptive terms unique to breast MRI are used to describe the internal enhancement pattern with a mass. Homogenous internal enhancement is uniform and suggestive of a benign lesion. Heterogenous internal enhancement describes non-uniform enhancement within the lesion and is suspicious, especially in the presence of rim enhancement. Rim enhancement is a highly suspicious finding for cancer, representing malignancy in up to 84% of cases, although this findign is only seen in 16% of cancers. Potential pitfalls are a peripherally enhancing inflammatory cyst or fat necrosis, both of which can demonstrate rim enhancement. Note that a cyst will be water-signal on T1- and T2-weighted images with a diagnostic ultrasound appearance, while fat necrosis will have central high signal on the non fat-suppressed T1-weighted images and a characteristic mammographic appearance. Enhancing internal septations and central enhancement are also suspicious for malignancy, although these patterns are less commonly seen compared to rim enhancement. Enhancing internal septations have a positive predicitve value for malignancy of \>95%. Dark internal septations are highly specific for a benign fibroadenoma (\>95% positive predictive value). A hyalinizing fibroadenoma, typically seen in older women, rarely enhances.

Answer 99

A focus is a small dot of enhancement \<5 mm in size that does not have any mass effect or correlate to any abnormality on precontrast images. A focus is too small for accurate assessment of margins or internal enhancement characteristics. Between 3 and 15% of foci are thought to represent cancer. The degree of suspicion for malignancy of a focus or foci depends on multiplicity and menstrual status. For instnace, multiple bilateral focie in a premenopausal patient would be much less concerning than a solitary focus in a postmenopausal patient, especially if new.

Answer 100

Non-masslike enhancement (NME) is an enhancing region that is not a mass or a focus. Similar to mamographic calcifications, non-masslike enhancement is described both in terms of distribution and morphology. The purpose of the lexicon for NMLE is to distinguish between malignancy and benign parenchymal enhancement or fibrocystic changes.

Answer 101

Linear/ductal: The distribution is arranged in a line or branching pattern pointing to the nipple, conforming to a duct. Linear/ductal distribution is up to 26% malignant, typically seen with a clumped enhancement morphology. Segmental: Triangular-shaped distribution of enhancement points towards the nipple. Similar to linear/ductal, segmental distribution suggests a ductal etiology. Segmental distribution is the most common distribution of DCIS (42% of DCIS cases). Focal area: Distribution is \<25% of a quadrant and contains interspersed fat/glandular tissue. Regional: Geographic distribution is \>25% of a quadrant. Multiple regions: At least two regions of NMLE are present. Diffuse: Uniform NMLE is present throughout the breast. A diffuse distribution of NMLE may be difficult to distinguish from background parenchymal enhancement.

Answer 102

Heterogenous: Enhancement is confluent and non-uniform in morphology. Heterogenous NMLE is seen in 21% of caes of DCIS. Homogenous: Enhancement intensity is uniform throught the NMLE. This pattern is more suggestive of a benign lesion compared to heterogenous, but small cancers may enhance homogenously. Clumped: The enhancement resembles a cobblestone pattern, also described as a "bunch of grapes". Clumped enhancement is most suggestive of DCIS, especially in a linear/ducta or segmental distribution. Clumped NMLE is seen in 51% of cases of DCIS. Stippled/punctate: Enhancement features tiny round dots and is associated with benignity. Reticular/dendritic: Enhancement is strand-like. Reticular/dendritic morphology may be associated with inflammatory carcinoma. The clinical use of this internal enhancement descriptor is not widespread in use and it may be removed from future versions of BI-RADS

Answer 103

Initial evaluation of the post-processed CAD angiomap or MIP images can give a global overview of any abnormal enhancement. The T2-weighted images are evaluated for the presence of hyperintense lesions. Although no specific BI-RADS nomenclature exists to describe the T2 characteristics of a mass, T2 hyperintensity within the enhancing portion of a mass is highly suggestive of a benign lesion. For instance, in younger women, myxoid fibroadenomas are typically hyperintense on T2-weighted images. Isolated evaluation of the signal characteristics on T2-weighted images is not a reliable method to classify a lesion as benign. For instance, mucinous carcinoma is typically hyperintense on T2-weighted images. The assessment of the T2-weighted images should be used as a secondary criterion to confirm benignity in a lesion that appears morphologically benign. T1-weighted images best show susceptibility artifact from biospy clips or calcifications and demonstrate hyperintense hemorrhagic cysts and proteinaceous ductal fluid. The principal aspect of the exam is the dynamic post-contrast images with post-processing to evaluate for the presence, morphology, and kinetics of any enhancing masses, foci, or NMLE.

Answer 104

Mass or NMLE with a type I kinetic curve and benign morphology: BI-RADS 2: Bilateral stippled foci of enhancement, without a dominant mass or suspicious focal NMLE. BI-RADS 3: Mass or NMLE with benign morphology and enhancement kinetics, and negative targeted ultrasound. In order for follow-up to be appropriate (rather than biopsy), the lesion must demonstrate only benign features on MRI. It is specifically these benign features, rather than the negative targeted ultrasound, that allow a lesion to be classified as BI-RADS 3. BI-RADS 4: Solitary, dominant, or asymmetric NMLE is a high risk patient. Mass or NMLE with type II or III kinetic curve and benign morphology: BI-RADS 4: A notable exception is a benign intramammary lymph node, which is typically located in the lateral breast adjacent to a vessel, and is reniform in shape. Mass or NMLE with type I kinetic and malignant morphology is generally classified as BI-RADS 4. A mass or NMLE with a type II-III kinetic curve and malignant morphology may be classified as BI-RADS 4 or 5.

Answer 105

Screening for cancer in high-risk patients is an accepted indication for breast MRI. High risk is defined as 20% or greater lifetime risk of developing breast cancer. There are several models for risk prediction taking into account family history, gene mutations, and exposures such as thoracic radiation (typically administered for treatment of lymphoma). BRCA1 or BRCA2 gene mutation carriers (or untested first-degree relatives of a confirmed carrier) are high risk, with 50-85% lifetime risk of developing breast cancer. MRI has been shown to detect occult breast cancer in 2-5% of high-risk women. There are no data to support screening breast MRI in women at average risk for breast cacner, even with dense breasts.

Answer 106

In patients with an established diagnosis of breast cancer, MRI can be helpful to evaluate the extent of diease and can change clinical management. The presence of two or more sites of cancer in one quadrant (multifocal disease) may preclude breast conservation, depending on the size of the breast. MRI has been reported to find additional cancer in teh same quadrant in 1-20% of women. The presence of cancer in more than one quadrant (multicentric disease) usually requires mastectomy. Unsuspected multicentric disease was found in MRI in 2-24% of women. MRI is highly accurate to measure tumor size. Compared to ultrasound and mammography, the tumor measurements determined by MRI have the highest correlation wiht pathology specimens. Ultrasound and mammography tend ot underestimate the ture size. MRI can assess for the presence of enlarged or abnormal axillary lymph nodes to suggest nodal metastasis. MRI can evaluate for pectoralis invasion. The presence of an enhancing lesion in the cotnralateral breast has been shown to have a relatively low positive predictive value for malignancy, of approximately 20%. For this reason, there has recently been a trend away from routine MRI screening of the contralateral breast due to the high number of false positives.

Answer 107

Breast conserervation therapy combines lumpectomy with radiation therapy and is teh treatment of choice for most early stage breast cancers. Negative surgical margins are required, and if the margins are positive then re-excision or mastectomy is indicated. MRI can evaluate for the extent of residual disease, which may manifest as small nodular areas of enhancement around the lumpectomy site.

Answer 108

Breast MRI is commonly performed in patients with treated breast cancer to evaluate for local recurrence or a metachronous primary in the ipsilateral or contralateral breast. Local recurrence rates at 15 years are 12% for women who received radiation and 36% for women who did not receive radiation. Following lumpectomy, normal enhancement at the lumpectomy site can be seen for up to 6-18 months due to granulation tissue. Enhancement at the lumpectomy scar beyond 18 months may no longer be normal. Of particular concern for recurrence is the reappearance of enhancement after the initial postoperative enhancement has subsided.

Answer 109

Neoadjuvant therapy is employed to reduce the size of large tumors prior to resection. Follow-up MRI performed even after one or two cycles of chemotherapy can evaluate whether the patient has responded to chemotherapy. Cytotoxic therapy may reduce tumor vascularity, which will often alter the enhancement kinetics of a lesion. After completion of neoadjuvant therapy, MRI can detect the location and extent of residual disease to guide surgical planning.

Answer 110

In certain situations, MRI can be useful for problem solving after a thorough mammographic and ultrasound workup remains indeterminate. For instance, an asymmetry that persists after spot compression but is not localizable on an orthogonal view or by ultrasound may be assessed by MRI.

Answer 111

MRI has the highest sensitivity and specificity for evaluation of silicone implant rupture. Unlike the standard breast mass protocol, no gadolinium is administered for an implant evaluation and this exam does not evaluate for cancer. Saline implants are typically evaluated by physical exam, mammography, and ultrasound. MRI is not indicated.

Answer 112

Implants can be used either for cosmetic reasons or for breast reconstruction after mastectomy. The two types of impants in common used are filled with either silicone or saline. Silicone implants contain a valve that allows filling of the implant during surgery. Regardless of the type of implant, a fibrous capsule is gradually formed as a reaction to the foreign body. The capsule may become calcified. Over time, the implant may partially herniate through the capsule without rupturing, causing a palpable contour deformity.. Implants can be placed either behind the pectoralis (retropectoral) or directly in front of the pectoralis/behind the fibroglandular tissue (prepectoral/retroglandular).

Answer 113

When implants are imaged with mammography, standard views are difficult to interpret because the high-attenuation implant can obscure breast tissue. Implant-displaced views (also called Eklund views) displace the implant posteriorly and pull the native breast tissue anteriorly to allow for improved compression and visualization of the breast tissue. A saline implant can be identified on mammography due to the presence of its valve. Additionally, the wall of the implant will be denser than the center because the wall is made of silicone elastomer that is denser than saline. In contrast, a silicone implant will be uniformely dense and no valve will be present.

Answer 114

Rupture of an implant can be contained within the fibrous capsule (Intracapsular rupture) or may extend out of the fibrous capsule (extracapsular rupture). In general, the distinction between intra- and extracapsular rupture is most important for silicone implants.

Answer 115

Rupture of a saline implant is usually evident clinically. Rupture causes suddent collapse and resultant instantaneous decrease in breast size. The residual implant wall collapses on itself and the saline is absorbed.

Answer 116

Intracapsular rupture of a silicone implant may manifest clinically as a subtle change in the implant contour but without significant change in the size or even shape of the breast. Rupture of a silicone implant can be challenging to diagnose clinically. Mammography is often normal, and ultrasound or MRI is usually necessary to diganose silicone implant rupture. MRI of intracapsular silicone implant rupture shows classic linguine sign, which describes the fragmented elastomer shell that is freely floating within the silicone contained within the fibrous capsule. Ultrasound of intracapsular silicone implant rupture shows segments of broken and collapsed implant wall floating within intracapsular silicone.

Answer 117

Extracapsular rupture of a silicone implant may be evident on mammography as high density silicone extending beyond the edge of the capsule into the breast parenchyma. On ultrasound, extracapsular silicone rupture causes free silicone to appear in the breast parenchyma, which has a classic snowstorm appearance on ultrasound

Answer 118

Reduction mammoplasty is performed for aesthetic reasons or to reduce back pain caused by large breasts. The surgeon removes breast parenchyma and skin from the inferior breast and relocates the nipple to a more superior location. The mammographic findings of reduction mammoplasty include skin thickening over the lower breast corresponding to the surgical scars. The lower breast features curvilinear architectural distortion. Fat necrosis may be present.

Answer 119

Gynecomastia is the benign development of glandular tissue in a male. It is the most common diagnosis of males evaluated for a focal breast complaint and clinically presents with a subareolar palpable abnormality. Gynecomastia may be due to cirrhosis, drugs (including antihypertensives and antidepressants), marijuana, pituitary hormone dysfunction, or a hormone-producing tumor. The typical mammographic appearance is a flame-shaped or triangular subareolar density. Mammography is sufficiently diagnostic. The ultrasound appearance is variable and may be misleading. Ultrasound is generally avoided if the mammographic views are diagnostic.

Answer 120

Male breast cancer accounts for less than 1% of all breast cancers. It tends to affect men greater than 60 years of age adn clinically presents as a palpable mass. While the typical appearance of male breast cancer is a spiculated mass, it is important to remember that a benign breast mass is very rare and any breast mass ina male should be regarded with suspicion Breast cancer may occasionally present as a round, circumscribed mass, which is just as suspicious as a spiculated mass.

Answer 121

Regardless of the method of biopsy, the radiologist must perform a radiology-pathology correlation of every case to ensure that the pathologic diagnosis is concordant with the imaging findings. Discordant findings should receive further workup, typically requiring repeat biopsy, either core or excisional. An example of a discordant finding is benign pathology (e.g., fragments of a fibroadenoma) for a highly suspicious, spiculated mass.

Answer 122

Ultrasound-guided core needle biopsy is the preferred approach for a lesion which is seen on ultrasound. Ultrasound-guided biopsy using standard freehand technique and a 14-gauge spring-loaded needle is a highly accurate method to biopsy breast masses. Ultrasound-guided interventions are the most user dependent and take time to master. Appropriate initial positioning of the patient and planning of the approach allows a smooth procedure. Some practioners always hold the ultrasound probe in the non-dominant hand to allow the dominant hand control over the needle. Other take an ambidextrous approach. It is critical when performing an ultrasound-guided procedure to always keep the biopsy device parallel to teh chest wall, or at a very shallow angle of obliquity. A standard breast biopsy needle advances approximately 2 cm when sampling. Far posterior lesions can be entered with the tip of the biopsy device and lifted anteriorly off th chest wall before sampling. A lateral approach to the lesion is generally preferred. The skin entry site should be an appropriate distance from the lesion, with posterior lesions requiring a larger distance between the lesion and the entry site to maintain a nearly parallel biopsy needle course. Once an entry site is chosen, cutaneous and subcutaneous anesthesia is administered under ultrasound guidance and a small dermatotomy is made. Multiple samples are obtained; each needle pass should be documented and needle positioning within the target demonstrated in an orthogonal plane for 1-2 passes. After adequate sampling, a titanium tissue marker clip is typically placed and post-procedure mammography is performed to confirm marker position.

Answer 123

The procedure for ultrasound-guided cyst aspiration is similar to that of a core needle biopsy. Instead of employing a spring-loaded biopsy gun, a standard syringe is attached to a 20- or 18-gauge needle and the targeted cyst is aspirated. The cyst aspirate should be sent for cytology if bloody or clear. Benign-appearing aspirate, which may be green, grey, yellow, or cloudy, may be discarded. Note that only benign-appearing cysts should be aspirated. A complex mass should be biopsied with a core device.

Answer 124

Stereotactic guidance is employed most commonly to biopsy calcifications. Less commonly, a stereotactic approach can be used to sample a mammographic finding seen only in one view or a mammographic mass not seen on ultrasound. Stereotactic biopsy tables can be prone or seated upright. The advantage of a prone table is elimination of risk from vasovagal syncope. The seated sterotactic apparatus is less expensiveand may offer greater patient comfort. Contraindications to stereotactic biopsy include a very thin breast measuring \<3 cm compressed (although petite needles are available to sample lesions in breasts as thin as 22mm), far posterior or subareolar location, inability to be positioned on the stereotactic table, and uncontrolled coagulation abnormality. Routine aspirin or colipidogrel use is not a contraindication. The breast is immobilized in compression during the entire procedure. Paired stereo spot views of the target are obtained 15° to each side (30° apart) relative to the needle path. Once targeting is confirmed by the radiologist, the actual needle path in three-dimensional space is calculated by computer. Generous local anesthesia is administered without and with epinephrine (both without imaging guidance) and a small dermototomy is made at the biopsy entrance site. A vacuum-assisted 11-gauge biopsy needle is employed and multiple samples are obtained. After the samples are obtained, the specimen must be radiographed to confirm the targeted calcifications are present. Once the presence of calcification is confirmed in the sample, a marker clip is placed, and post-procedure 2-view mammograms are obtained to confirm clip position. Often, small calcifications will be completely removed by the vacuum-assisted biopsy and correct position of the clip is essential if the lesion requires subsequent surgical treatment.

Answer 125

MR-guided biopsy can be performed for lesions seen only on MRI. It is common to perform a second-look ultrasound targeted towards the MRI abnormality, which is seen on ultrasound 57% of the time. Second-look ultrasound is performed both for further characterization and to potentially provide a less-expensive biopsy guidance modality, assuming the lesion is visualized and accurately correlates to the MRI findings. MR-guided biopsy almost always requires intravenous gadolinium. Time is of the essence during the procedure because the lesion must be targeted before contrast washes out or the lesion becomes obscured by delayed parenchymal enhancement. The grid-coordinate method allows accurate biopsy of an abnormality seen only on MRI. This method is most analogous to a grid-based CT-guided biopsy elsewhere in the body. With the patient lying prone, a grid is applied to either the medial or lateral breast. A lateral approach is preffered whenever possible. After initial images are obtained, the targeted lesion is localized on the grid. Local anesthesia is administered without imaging guidance. During the biopsy, the core needle device is inserted exactly perpendicular to the breast to a pre-measured depth, similar to stereotactic biopsy. Multiple 9-11-gauge vacuum-assisted samples are obtained. Finally, a post-biopsy marker is deployed.

Answer 126

Mammographic-guided wire localization allows pre-operative localization of a mammographic lesion prior to excisional biopsy or lumpectomy. The shortest approach to the lesion should be used and an appropriate wire length should be chosen (typically 5, 7, or 9 cm). After the lumpectomy or excisional biopsy, specimen radiographs are obtained to confirm that the targeted lesion and the intact hook wire are contained wihin the specimen.