Breast Imaging Flashcards
Imaging breast cancer: Key facts
Breast cancer is the most common female cancer in the United States. The average woman has a one in eight chance of being diagnosed with breast cancer during her lifetime.
Mammography is the first-line tool for detection of breast cancer; however, the sensitivity of screening mammography for detecting cancer has been estimated at between 68% and 90%, with the lower range of this scale true for mammographically dense tissues. Of note, diagnostic mammography (used ot evalute a patient with signs or symptoms suggestive of breast cancer) has a higher sensitivity, up to 93%.
Ultrasound is a critical adjunct imaging modality to mammography, but ultrasound is not used for screening. The indications for performing breast ultrasound are characterization of palpable abnormalities, further characterization of mammographic findings, first-line evaluation of a breast abnormality in a young (under age 30), pregnant, or lactating woman, guidance for interventional procedures, and evaluation of breast implants.
MRI is an established breast imaging modality. The indications for breast MRI include screening in high-risk patients (greater than 20% lifetime risk of developing breast cancer), evaluation of extent of disease in a paitent newly diagnosed with breast cancer, evaluation of neoadjuvant chemotherapy response, assessment for residual disease after positive surgical margins, evaluation for tumor recurrence, and evaluation for occult breast cancer in a patient with axillary metastases.
The pathway of invasive ductal breast cancer progression
The current understanding of progression to ductal breast cancer is a multi-step transformation from normal cells to flat epithelial atypia (FEA), to atypical ductal hyperplasia (ADH), to ductal carcinoma in situ (DCIS), to invasive ductal carcinoma (IDC).
ADH is intraductal proliferation with cytological atypia but without the definitive architectural or cytological abnormalities of DCIS. FEA is related to ADH and is characterized by abnormal ductal cells. FEA and ADH are considered non-obligatory precursor lesions; that is, the presence of ADH or FEA is an indicator of a higher risk of developing breast cancer, rather than an obligatory precursor towards invasive cancer.
If a core biopsy shows FEA, excisional biopsy is advocated by several authors. 14% of patients with a core needle biopsy of FEA will be upstaged to DCIS or invasive carcinoma upon surgical excision.
A core biopsy with pathology of atypical ductal hyperplasia (ADH) is followed by surgical excision. Approximately 18% of ADH diagnosed by core needle biopsy will be upstaged to either invasive carcinoma or DCIS upon surgical excision.
Ductal carcinoma in situ (DCIS) is most often occult cancer detected mammographically and is treated surgically. Breast imaging plays an essential role in the diagnosis of DCIS as DCIS is typically asymptomatic and nonpalpable. Histologically, DCIS represents carcinoma contained within the duct, with an intact basement membrane surrounding the duct. Between 30-50% of patients with DCIS will develop invasive carcinoma within 10 years. Approximately 43% of DCIS diagnosed by ultrasound-guided core needle biopsy is upstaged to invasive carcinoma upon surgical excision.
Risk factors for developing breast cancer
The two most important risk factors for breast cancer are female sex and advancing age. Other important risk factors for breast cancer include:
Inherited BRCA1 or BRCA2 mutation. Women with an inherited mutation have greater than 50% chance (some believe as high as 80% chance) of developing breast cancer by age 80.
First degree relative with breast cancer. In contrast, a non-first degree relative with postmenopausal breast cancer is not considered an increased risk.
Prior chest radiation for Hodgkin or non-Hodgkin lymphoma.
Long-term estrogen exposure, such as early menarche, late menopause, late first pregnancy, nulliparity, or obesity (through increased estrogen production by adipocytes).
Prior biopsy result of a high risk lesion in the lobular neoplasia spectrum, including atypical lobular hyperplasia (ALH) and lobular carcinoma in situ (LCIS). Unlike ADH and FEA, which are high risk lesions in the ductal neoplasia spectrum, the high risk lesions in the lobular neoplasia spectrum are not treated with surgical excision. ALH and LCIS arise from the terminal duct lobule, can be distributed diffusely throughout the breast, and are considered a marker of increased risk rather than a precursor to invasive carcinoma. Women with LCIS have a 30% risk of developing invasive cancer (usually invasive ductal), which may occur in either breast.
Special histologic subtypes of invasive ductal carcinoma
Breast cancer is a diverse spectrum of disease with varying histopathology and prognosis.
The most common subtype of breast cancer is invasive ductal carcinoma (IDC), representing 70-80% of cases. It often presents as a palpable mass, usually with a classic mammographic appearance of a spiculated mass, architectural distortion, and pleomorphic calcifications.
Combined, a number of less common subtypes make up less than 10% of all breast cancers. In general, these special subtypes have better prognosis than invasive ductal carcinoma not otherwise specified (IDC NOS).
Special subtypes of ductal breast cancer
Tubular carcinoma is a low grade cancer that typically presents as a small spiculated mass. Prognosis is better than IDC NOS. It may be difficult for the pathologist to distinguish between radial scars/complex sclerosing lesions and tubular carcinoma, and it is thought that radial scar may be a precursor to tubular carcinoma.
Mucinous carcinoma (synonyms: colloid carcinoma, mucoid carcinoma, and gelatinous carcinoma) typically is a low-density circumscribed mass that can mimic a fibroadenoma on ultrasound. On MRI mucinous carcinoma usually appears hyperintense on T2-weighted images.
Medullary carcinoma is a rare variant of breast cancer, typically seen in younger women, often with BRCA1 mutation. Medullary carcinoma is locally aggressive, but has a better prognosis than IDC NOS.
Papillary carcinoma is the malignant form of an intraductal papilloma.
Adenoid cystic carcinoma is a very rare breast cancer that presents as a palpable firm mass. Prognosis is excellent with complete resection.
Invasive lobular carcinoma
Invasive lobular carcinoma comprises approximately 5-10% of breast cancer cases. Compared to invasive ductal carcinoma, invasive lobular is typically much more difficult to diagnose mammographically and clinically due to its tendency to spread through the breast tissue without forming a discrete mass.
Invasive lobular carcinoma presents an imaging challenge due to its elusive appearance, which ranges from a one-view asymmetry to architectural distortion to a spiculated mass.
Inflammatory carcinoma
Inflammatory carcinoma represents tumor invasion of dermal lymphatics.
Clinically, inflammatory carcinoma presents with breast erythema, edema, and firmness.
On mammography, the affected breast is larger and denser, with trabecular thickening and skin thickening. Occasionally, no discrete mass will be apparent. The primary differential consideration is a breast abscess; however, the clinical setting and exam will usually be able to differentiate.
Paget disease of the nipple
Paget disease of the nipple is a form of DCIS that infiltrates the epidermis of the nipple.
Clinically, Paget disease of the nipple presents with erythema, ulceration, and eczematoid changes of the nipple.
Breast cancer prognosis
In non-metastatic breast cancer, axillary lymph node status is the most important prognostic factor, with the absence of nodal involvement offering the highest likelihood of cure. Similarly, survival is progressively worse with increased number of involved axillary nodes. The primary method to detect axillary involvement is a surgical sentinel lymph node biopsy, with a sensitivity of 93%. Sentinel lymph node biopsy is not routinely performed for DCIS unless necrosis or microinvasive disease is present. Surgical axillary lymph node dissection has a 99% sensitivity for detecting lymph node involvement. Lymph node diessection is performed if the sentinel lymph node is positive or not identified. Women with positive lymph nodes or with large tumors may benefit from neoadjuvant chemotherapy.
The presence of tumor receptors affects prognosis. Patients with estrogen receptor (ER) and progesterone receptor (PR) positive tumors have longer disease free survival. Cancers with HER2/neu overexpression may respond to the monoclonal antibody trastuzamab (brand name Herceptin) or tyrosine kinase inhibitors such as lapatnib.
Triple-negative cancers are ER, PR, and HER2/neu negative, are biologically aggressive, and portend a poor prognosis. Triple negative cancers are seen most often in patients with BRCA1 mutation. It has been suggested that triple-negative cancers may show benign featrues on mammography and ultrasound despite their aggressive nature. They are often round with smooth margins, without spiculations and calcifications, and are located posterioly in the breast.
There are several histologic subtypes of DCIS, with varying prognosis. A key factor to determine the prognosis of DCIS is the presence of necrosis. DCIS without necrosis (cribiform and micropapillary subtypes) is lower grade. Sentinel node evaluation is usually not indicated. DCIS with necrosis (poorly differentiated, comedo, and large-cell subtypes) is higher grade. On mammography, the typical manifestation of high-grade DCIS is pleomorphic or fine linear branching calcifications, which are caused by calcfication of necrotic debris in the duct lumen. Sentinel lymph node biopsy is often performed for high-grade DCIS.
Fibrocystic change (Cyclical and proliferative breast disease)
Fibrocystic change is an essentially normal pattern of breast physiology.
Clinically, fibrocystic change presents as cyclical breast pain, sometimes with a palpable lump. Fibrocystic change is almost always seen in pre-menopausal women.
Imaging findings are not specific and fibrocystic change is not ever a diagnosis made on imaging. Its only significance is that it may cause certain imaging abnormalities that instigate further workup, such as cysts and calcifications.
Sclerosing adenosis
Sclerosing adenosis is a benign proliferative lesion caused by lobular hyperplasia and formation of fibrous tissue that distorts the glandular elements.
Similar to fibrocystic change, the imaging importance of sclerosing adenosis is that is can mimic DCIS with microcalcifications.
Mastitis
Mastitis is infection of the breastl, most commonly by Staphylococcus aureus. It is typically seen in nursing mothers (called lactational or puerperal mastitis) or in diabetic patients.
Clinically, mastistis presents with breast pain, induration, and erythema.
Imaging is usually not performed, but mammography or ultrasound can show focal or diffuse skin thickening, breast edema, and adenopathy.
Treatment is antbiotics. If inadequately treated, mastitis can develop into a breast abscess.
Breast abscess
A breast abscess is a walled-off purulent collection, typiaclly from S. aureus.
Clinically, breast abscess appears as an irregular mass, which can mimic carcinoma based on imaging appearance alone.
Ultrasound shows an ill-defined mass with heterogenous echoes and irregular margins. An internal fluid level may be present. The primary differential consideration is inflammatory carcinoma; however, the clinical setting and exam will usually be able to differentiate.
Treatment is ultrasound-guided aspiration in addition to antibiotics.
Granulomatous mastitis
Granulomatous mastitis is a rare idiopathic noninfectious cause of breast inflammation that occurs in young women after childbirth.
Granulomatous mastitis may be associated with breast feeding or oral contraceptives.
The mammographic and sonographic features of granulomatous mastitis may mimic breast cancer and biopsy is usually warranted.
Periductal mastitis
Periductal mastitis, also known as plasma cell mastitis, is caused by the irritating contents of intraductal lipids. It is seen in post-menopausal women and produces the classic mammographic appearance of large, rod-like secretory calcifications.
Diabetic mastopathy
Diabetic mastopathy is a sequela of long-term insulin-dependent diabetes. An autoimmune reaction to matrix proteins from chronic hyperglycemia causes a firm and sometimes painful mass.
On mammography, diabetic mastopathy can appear as an ill-defined, asymmetric density without microcalcifications.
Ultrasound typically shows a hypoechoic mass or regional acoustic shadowing, mimicking the appearance of a scirrhous breast cancer.
Because the mammographic and sonographic appearanc can mimic breast cancer, core biopsy is required.
Mondor disease
Mondor disease is thrombophlebitis of a superficial vein of the breast, most commonly the thoracoepigastric vein.
Clinically, Mondor disease presents with pain and tenderness in the region of the thrombosed vein. A cordlike, elongated superficial mass may be present.
Ultrasound shows a dilated, “bead-like” tubular structure with no flow on color Doppler.
Screening Mammography
The goal of screening mammography is to detect pre-clinical breast cancer in asymptomatic women. Screening mamography detects 2 to 8 cancers per 1,000 women screened.
Since 1990, the mortality from breast cancer has been steadily declining at a rate of approximately 2.2% per year, thought to be due to improvements in adjuvant therapy and screening mammography. The current American Cancer Society guidelines (2010) for screening mammography recommend annual screening for women over age 40 (or 10 years younger than a first degree relative with breast cancer).
In 2009, the US Preventative Services Task Force (USPSTF) reclassified the evidence for screening of women age 40-49 from a class B (moderately strong evidence) to a class C (based on individual factors) recommendation, and also recommend reducing the screening interval between ages 50-74 to biannually. This has caused considerable controversy.
Statistical models show that screening starting at age 40 (instead of age 50) would avert one additional death from breast cancer for every 1,000 women screened, with a resultant average of 33 life-years gained per 1,000 women screened.
The potential concerns for mammographic screening include a very small risk of inducing breast cancer from radiation exposure, and risks of over-diagnosis including anxiety from false positives and unnecessary biopsies.
No single radomized trial has shown a mortality reduction due to mammographic screening in women age 40-49; however, several meta-analyses have shown a reduction in breast cancer specific mortality of 15-20%.
It is generally accepted that women at 50-69 benefit from annual screening mammography, with a 14-30% reduction in breast-cancer mortality in those women participating in screening mammography.
There are no strong data to support screening mammography in women over age 70.
Routine screening mammographic views
The two standard mammographic views are cranio-caudal (CC) and medial-lateral-oblique (MLO).
The cranio-caudal (CC) image plane is transaxial.
The medial-lateral-oblique (MLO) image plane is approximately 45 to 60 degrees from the axial plane, paralleling the course of the pectoralis muscle heading into the axilla. The MLO view is ideal for screening, as it captures most of the breast tissue in a single view. Note that the superior-medial breast tissue may be excluded on the MLO view.
At the technologists discretion, additional views may be performed to iamge all of the glandular tissue: Cleavage view (CV) images the medial breast of tissue of both breasts. The exaggerated CC (XCC) view pulls either lateral or medial tissue into the imaging detector.
Online and Offline screening
Typically, most scrrening mammography is interpreted offline, where a batch of exams are reviewed in bulk some time after the films were taken.
Online screening, where women have mammography performed and then wait ot get a final report from the radiologist, leads to more imaging being performed and more false positives, with the same cancer detection rate.
In contrast to screening mammography, all diagnostic mamography is performed “online” as a monitored exam with the patient staying for all possible imaging and the final results/recommendations before leaving.
Indications for diagnostic mammography
Diagnostic mammography is usually performed for a breast problem (pain, lump, skin thickening, nipple discharge).
Other indications of diagnostic mammography include annual mammography in an asymptomatic women with a past history of breast cancer, short interval follow-up (following of BI-RADS 3 lesions), and evaluation of an abnormality found on screening mammogram.
Diagnostic mammography procedure
Any mammographic abnormality is first localized in three dimensional space, then worked-up with special problem-solving techniques.
Often, ultrasound is added at the radiologist’s discretion.
Each patient waits until all imaging is completed before receiving a summary of the final interpretation and recommendations from the radiologist.
Evaluate image quality and adequacy
The first step in evaluating a mammogram is to determine if the study is tecnhically adequate.
There should be adequate tissue imaged on both the CC and MLO views. The posterior nipple line is a line drawn from the posterior nipple to teh pectoralis muscle - or edge of the film on the CC view if the pectoralis is not visualized. The posterior nipple lines drawn on the CC and MLO views should be within 1 cm of each other.
The image must be free from blur and artifacts. The trabeculaeshoudl be sharp; if blur is present, then benign calcifications can be mistaken for suspicious amorphous calcifications, and subtle calcifications can be missed entirely.
The nipple of each breast should be in profile in at least one view.
Each projection should be globally compared side-to-side to evaluate for symmetry.
Each image should be carefully evaluated for signs of malignancy. The mammographic signs of malignancy are mass, calcification, architectural distortion, and asymmetry. Calcifications are best viewed at 1:1 or higher magnification, while architectural distortion is best seen when the whole breast is visualized.
When viewing a digital mammogram, every portion of the image should be carefully evaluated at 1:1 zoom.
Even if a study appears unremarkable at first glance, comparison to prior exams can often reveal a subtle progressive change. For instance, an apparently normal island of parenchymal tissue may be slowly growing and represent malignancy.
In general, it is best to carefully compare the previous exam from at least two years prior, to appreciated slowly growing changes.
BI-RADS Assessment Categories
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.
Fibroglandular density
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.
Skin thickening
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.
Mass vs Asymmetry
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.
Evaluating margins using BI-RADS lexicon
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.
Describing density
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.
Describe the shape
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.
Describe the location, by naming the quadrant and (optionally) the depth
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.
Associated features (Mammo)
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.
Overview of skin calcifications
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.
Skin Calcifications
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.
Vascular calcifications
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.
Coarse or “popcorn” calcifiations
“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.
Milk of calcium calcifications
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.
Sutural calcifications
Sutural calcifications represent calcium deposited on suture material, usually after radiation therapy.
Sutural calcifications are uncommonly seen due to changes in modern surgical technique.
Dystrophic calcifications
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.
Round calcifications
Round calcifications are due to various etiologies and are benign.
Punctate calcifications
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.
Lucent-centered calcifications
Benign, smooth calcifications with a lucent center can range in size from less than 1 mm to greater than 1 cm in diameter.
“Eggshell” or “rim” calcifications
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.
Amorphous or indistinct calcifications
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.
Coarse heterogenous calcifications
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.
Fine pleomorphic calcifications
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.
Fine linear or fine-linear branching calcifications
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.
Distribution of Calcium
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.
Diffuse/scattered calcifications
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.
Regional calcifications
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.
Linear
Linear calcifications are arrayed in a line.
Linear distribution of calcifications elevates suspicion for malignancy as this suggests calcium deposits within a duct.
Segmental
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.
Grouped or clustered
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.
Spot compression (with or without magnification)
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.
XCC (exaggerated cranio-caudal)
The lateral XCC (XCCL) pulls lateral breast tissue into the detector.
The medial XCC (XCCM) pulls medial breast tissue into the detector.
Rolled views (CC variant)
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.
Reduced compression
Images with reduced compression can be obtained to image far posterior lesions that may “slip out” of the detector when full compression is applied.
True lateral view (ML or LM)
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.
Triangulation
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)
Normal zonal anatomy
Enhancement Kinetics
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.
Overview of Implant rupture
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.
