Mammography BI-RADS Introduction The breastimagingreportinganddatasystem(BI-RADS), proposed by the American College of Radiology in 1992, is now in its fourth edition. This system plays a great role in standardizing mammography reporting, reducing confusion in image depiction, and monitoring of screening. Common signs (a) Mass: an occupying lesion with bulging edges that is visible in two different projection locations, with marginal signs being the most important in determining the nature of the mass. A suspicious mass seen in only one projection is called a “dense shadow”; one without obvious bulging edges is called “asymmetric”. The description of the mass includes three aspects: morphology, margin, and density. The first three morphologies should be considered in conjunction with other signs and symptoms. The margins are most important in diagnosing the nature of the lesion and include the following five descriptions: clear, blurred, lobulated, infiltrated, and asterixis. Clear margins mean that more than 75% of the mass is clearly and sharply demarcated from the surrounding normal tissue, and the remaining margins may be obscured by the surrounding glands without evidence of malignancy; blurred means that the mass is obscured by the normal tissue above or adjacent to it, making it impossible to judge it further. Infiltrates are irregular borders caused by infiltration of the lesion itself into the surrounding area and not due to obscuration of the surrounding glands; stellate is seen as a radiolucent shadow emanating from the edge of the mass. Small lobulated, infiltrative and asterixis edges are signs of malignancy. It is sometimes difficult but important to distinguish between blurred margins, which are mostly benign, and infiltrates, which are malignant, and localized compression photography and tamponade techniques are helpful. Density is described as high, isodense, low (excluding fatty density) and fatty density compared to the mass and its surrounding breast tissue of the same volume. Most breast cancers are high or isodense; a very small number of breast cancers may be hypodense; breast cancers do not contain fat density, which is a benign manifestation. (B) Calcification: Benign calcification is often larger than malignant calcification, showing rougher calcification or round calcification with clear edges. Malignant calcifications are often smaller and require magnification to help show them. The calcifications are described in terms of both morphology and distribution. Benign calcifications may not be depicted, but they need to be described when they may be misinterpreted by another physician. The morphology is divided into typical benign calcifications, intermediate calcifications (suspicious calcifications), and calcifications of high malignant potential. Typical benign calcifications have the following 10 typical manifestations: coarse cutaneous calcifications, typically with translucent central changes, atypical ones can be identified with the help of cut line projections; vascular calcifications that appear tubular or track-like; coarse or popcorn-like calcifications often larger than 2-3 mm in diameter, characteristic of fibroadenoma calcifications; coarse rod-like calcifications that are continuously rod-like, occasionally branching, usually larger than 1 mm in diameter, and may appear They may be centrally translucent, with well-defined margins, distributed along the ducts and clustered towards the nipples, often bilaterally, and are often seen in secretory lesions; round and punctate calcifications, less than 1 mm or even 0.5 mm, often located in lobular follicles, and clustered should be alerted; “ring-shaped” or “eggshell-like calcifications “ring” or “eggshell” calcification, with thin walls, often less than 1mm, is a spherical object surface deposits of calcification, seen in fat necrosis or cysts; hollow calcification size can range from 1mm to 1cm or even larger, smooth edge round or ovoid, the central is low density, the wall thickness is greater than “ring” or “eggshell” calcification. “Milk-like calcification is intracystic calcification, which is not obvious in the cephalopodal axis (CC), is fluffy or indeterminate in shape, has a clear border at 90° lateral view, and is hemimelanotic, crescentic, curvilinear or linear depending on the cyst morphology, Dystrophic calcification is often seen in post-radiotherapy or post-traumatic mammary glands, with irregular calcification patterns, mostly larger than 0.5 mm, with hollow changes. Intermediate calcification (suspicious calcification) includes two types of calcification: indefinite fuzzy calcification and rough inhomogeneous calcification. Indeterminate fuzzy calcifications: morphologically they are often small and fuzzy without typical features, and their diffuse distribution is often benign, while clustered distribution, regional distribution, linear and segmental distribution need to be referred to clinical biopsy. Coarse inhomogeneous calcifications: mostly larger than 0.5 mm, with irregular morphology may be malignant, but can also be found in benign fibrosis, fibroadenoma and post-traumatic breast, and need to be considered in conjunction with distribution. Highly malignant calcifications may also present in two forms, small polymorphic calcifications (granular punctate calcifications) and linear or linear branching calcifications (cast calcifications). Granular punctate calcification is more suspicious than indeterminate calcification and is variable in size and shape, often less than 0.5 mm in diameter. Linear branching calcification presents as fine, irregular lines, often discontinuous, less than 0.5 mm in diameter, and these signs suggest that the calcification is formed in the lumen of the duct invaded by breast cancer. Highly malignant calcifications may be characterized by heterogeneity, including morphology, size, and density. The distribution of calcifications is often helpful in indicating the pathological type of breast lesion and includes the following five distribution patterns. Diffuse or scattered distribution refers to calcifications randomly dispersed throughout the breast; point-like and polymorphic calcifications distributed in this way are mostly benign changes, often bilateral; zonal distribution refers to calcifications distributed over a larger area (>2 cm × 2 cm × 2 cm) but not depicted by a duct-like distribution, often exceeding the extent of one quadrant; the nature of this calcification distribution needs to be considered in conjunction with the morphology; clustered distribution refers to calcifications with at least The linear distribution of calcifications with a linear arrangement and visible branching points suggests that the lesion originates from one duct and is mostly malignant; the segmental distribution often suggests that the lesion originates from one duct and its branches, or it may occur as a multifocal carcinoma in one lobe or one segment, although benign secretory lesions may also have segmental distribution. Although benign secretory lesions may also have segmental distribution of calcifications, if the morphology of calcifications is not characteristically benign, they are first considered to be malignant calcifications. (iii) Structural distortion: This refers to distortion of normal structures without clear mass visibility, including radiolucency and focal constriction emanating from a point, or distortion at the edges of the parenchyma. Structural distortion can also be a concomitant sign of a mass, asymmetric densities, or calcifications. In the absence of a local history of surgery or trauma, structural distortion may be a sign of malignant or radiolucent scarring and should be referred for clinical excisional biopsy. II. Special Signs (i) Asymmetric tubular structures/single dilated duct: tubular or branch-like structures may represent dilated or thickened ducts. It is of little significance if not accompanied by other suspicious clinical or imaging signs. (ii) Intramammary lymph nodes: typically kidney-shaped, with visible translucent cut marks due to lymph node portal fat, often less than 1 cm. when the lymph nodes are large but their majority is fatty replacement, they are still benign changes. It can be multiple, or a single lymph node may look like multiple round nodal shadows due to significant fat replacement. A correct diagnosis can be made for characteristic changes in the upper outer part of the breast. Occasionally, they may be present in other areas. (iii) Mass asymmetry: The diagnosis can be made by comparison with the contralateral breast tissue, which is larger in extent up to at least one quadrant. It includes a larger breast tissue that is denser than normal breast tissue or has more pronounced ducts visible, no focal mass formation, no structural distortion, and no accompanying calcifications. Often represents a normal variant or is the result of replacement hormone therapy. However, when coincident with clinical palpable asymmetry, it may have clinical significance. (iv) Focal asymmetry: a dense change that cannot be accurately described by other shapes. Both projection locations are shown, but lack the marginal changes characteristic of true masses and are less extensive than mass asymmetry. It may represent a normal breast island, especially when it contains fat. However, due to its lack of characteristic benign signs, it often requires further examination, which may reveal a true mass or significant structural distortion changes. Combined signs Often combined with masses or calcified signs, or as separate changes not accompanied by other abnormal signs. These include skin indentation, nipple depression, skin thickening, trabecular thickening, skin lesions projected in the breast tissue, axillary lymph node enlargement, structural distortion, and calcification. Overall assessment i. Assessment is incomplete Grade 0: requires other imaging studies for further evaluation or comparison with the anterior film. Often applied in census situations and rarely used after complete imaging and comparison with the anterior film. Other imaging methods recommended include localized compression photography, magnification photography, special projection body photography, ultrasound, etc. Second, the evaluation is complete (a) Grade 1: Negative. No abnormal findings. (ii) Grade 2: benign findings. These include calcified fibroadenomas, multiple secretory calcifications, fat-containing lesions (lipid cysts, lipomas, ductal cysts and mixed density mismatched tumors), intramammary lymph nodes, vascular calcifications, implants, distorted structures with a history of surgery, etc. However, in general there are no radiographic signs of malignancy. (c) Grade 3: Probably benign findings, with short-term follow-up recommended. There is a high probability of benignity and the expectation is that this lesion will stabilize or shrink during short-term (less than 1 year, usually 6 months) follow-up to confirm the judgment. The malignancy rate at this level is generally less than 2%. The three signs of a well-defined mass without calcification, focal asymmetry, and clustered round or/and punctate calcification are considered to have a high likelihood of benign changes. For this level of management, a short-term follow-up of radiographs (6 months), followed by 6 months and 12 months to 2 years or more of stability, was used to confirm his determination. 2 or 3 years of stability allowed a grade 2 (benign) from the original grade 3 reading (probably benign). This grading is used after complete imaging evaluation and is generally not recommended for initial screening; it is also inappropriate for the evaluation of clinical findings and masses; and biopsy should be recommended rather than continued follow-up for potentially benign lesions that appear to increase in size during follow-up. (iv) Grade 4: suspicious abnormalities to be considered for biopsy. This level includes a large group of lesions requiring clinical intervention. Such lesions do not have characteristic morphological changes of breast cancer but have the possibility of malignancy, with an overall malignancy rate of about 30%. This category is further divided into 4A, 4B and 4C, where clinicians and patients can make the final decision on the management of the lesions according to their different malignant potential. 1.4A: This includes a group of lesions that require biopsy but have a low malignant potential. The results of biopsies or cytology that are benign can be relied on more and can be followed up routinely or after six months. Substantial masses with well-defined margins on palpable radiographic presentation and ultrasound suggestive of possible fibroadenoma, palpable complex cysts, and palpable abscesses are classified in this subclass. 2.4B: Moderate malignancy was possible. It is important to reach a consensus between the radiologist and the pathologist regarding the credibility of the puncture biopsy findings in this group of lesions. Puncture of a partially defined, partially infiltrated mass as fibroadenoma or fat necrosis is acceptable and is followed up. In contrast, further excisional biopsies are needed to confirm puncture findings of papilloma. 3.4C: A group of lesions that are further suspected to be malignant but have not reached the typical grade 5 level. Irregularly shaped parenchymal masses with infiltrating margins and clusters of small pleomorphic calcifications may be included in this subgrade. Those with an image reading of grade 4, regardless of subgrade, should be followed up regularly after benign pathological findings. In contrast, for those with imaging grade 4C and benign pathological puncture results, further evaluation of the pathological findings should be performed to clarify the diagnosis. (E) Grade 5: High suspicion of malignancy and appropriate clinical measures should be taken (almost certain malignancy). This category of lesions has a high likelihood of malignancy. The likelihood of detecting malignancy is greater than or equal to 95%. High-density masses with irregularly shaped stellate margins, segmental and linear distribution of fine linear and branching calcifications, and irregularly shaped stellate marginal masses with polymorphic calcifications should be classified in this grade. (f) Grade 6: Biopsy has confirmed malignancy and appropriate measures should be taken. This grading is used in the imaging evaluation of biopsy-proven malignancy but not yet treated. The main purpose is to evaluate imaging changes after prior biopsy or to monitor imaging changes from neoadjuvant chemotherapy prior to surgery.