The mammary glands are located between the superficial and deep layers of the superficial subcutaneous fascia. The superficial fascia extends into the mammary tissue to form a lobular septum with one end attached to the pectoralis fascia and the other end attached to the skin, which anchors the mammary glands in the subcutaneous tissue of the chest. The mammary glands are located on both sides of the anterior chest wall, between the second and sixth ribs. They are conical in shape and vary greatly depending on physiological status (childbirth, breastfeeding), age, fatness, etc. Breast augmentation is currently one of the common clinical cosmetic surgery, and its common ways are: ① prosthesis placement: the main contents are: silicone gel, saline, dextrose, polyene acetone, vegetable oil, etc. (single-chamber silicone and saline prosthesis are the most common); ② prosthesis injection: polyacrylamide hydrogel (i.e., Omnidene, Hydrophilic polyacrylamide gel (PAAG) ); ③ autologous fat transplantation: mostly injections are used. The main target groups of breast augmentation: ① small, flat breasts; ② sagging breasts; ③ unbalanced breast development; ④ breast dysplasia; ⑤ breast reconstruction after surgery for malignant tumors of the breast. After breast augmentation, the structure and shape of female breast are changed. The main methods of breast imaging are mammography, MRI, CT, etc. Mammography (mammography and CR) is the preferred examination method for breast diseases and a screening tool for breast diseases. It can show calcification and detect early breast cancer, and is simple, economical and experienced in diagnosis, but it is difficult to show micro lesions and tumors occurring after breast augmentation, and it is difficult to distinguish benign and malignant tumors. MRI examination has high resolution for soft tissues, can be multi-directional and multi-parameter imaging, and is an important examination method for breast diseases. It has a sensitivity of 94-100%, high accuracy in identifying benign and malignant lesions, can show multiple foci in the breast and whether the fatty space behind the breast and the pectoral muscle are involved, can show tumors in the breast after breast augmentation, and can provide three-dimensional and intuitive imaging information for the identification of post-augmentation materials and the performance of complications, which can provide unprecedented help for clinicians to develop accurate surgical plans and complete removal of breast augmentation materials, but It cannot show calcification and the cost of examination is high. CT examinations can show the anatomical structures within the breast and can detect smaller breast lesions, as well as show the condition of the chest wall and axillary lymph nodes, and are used as a supplement to mammography. Normal breast imaging Mammograms are usually used for axial (cephalic CC) and oblique (MLO) views (Figure 1), preferably 1-2 weeks after menstruation; the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) classifies the difference in density of the breast on X-rays into four types: polyglandular, microglandular, dense, and fatty. dense type, and fatty type. In adolescence, the breast is mainly glandular tissue with a uniform dense shadow, subcutaneous fat and interglandular fat with a ground glass-like density, and radial distribution of breast ducts; in adulthood and lactation, the glands proliferate and increase in fat, with a nodular dense shadow; in old age, the glandular atrophy is mainly connective tissue and fatty tissue; it shows a low-density background with a concentration of cords and reticular shadows toward the nipple. It is often observed by bilateral control method. Due to the large overlap of tissues, silica gel leaking into the mammary gland or into the muscle space may be missed. CT examination of the breast: normal breast skin is arcuate shadow, 5-15mm thick; subcutaneous fat is visible, CT value -50Hu; the gland is small piecewise or mass-like soft tissue shadow, CT value 10-20Hu; the posterior interstitial boundary of the breast is obvious. The measurement of CT value can determine the cystic change, bleeding, necrosis and calcification of the lump. Breast MRI: A foot-advanced approach is used to lie prone on a special breast phased-array coil, with a transverse view predominantly supplemented by sagittal and coronal views. TIWI is useful for observing the anatomical distribution of breast fat and glands, and T2WI images are valuable in diagnosing cysts or fibroadenomas. Normal breast MRI fractionation Imaging performance after breast augmentation Mammography X-ray X-ray performance under normal conditions: After breast augmentation with prosthesis implantation, high-density prosthetic shadow in front of the pectoral muscle and behind the gland, hemispherical, with smooth edges, uniform density and thin envelope. Silicone gel prosthesis and saline prosthesis, x-ray performance of the two density is similar, more difficult to distinguish. After injection of medical polyacrylamide hydrogel breast augmentation, the breast is dense and uniform, with no obvious density difference from the normal gland, and no obvious envelope contracture shadow. There is no clinical discomfort and other symptoms. X-ray performance under abnormal conditions: after implantation of breast augmentation, there is no obvious change in the position and shape of the prosthesis, but obvious uneven thickening of the envelope around the prosthesis, higher density of the surrounding glands, more chaotic structure, no obvious calcification. After injection of medical polyacrylamide hydrogel breast augmentation, the density of the breast is not uniform, may be irregular mass shadow, surrounded by a low-density envelope, the thickness of the envelope varies, the border is unclear. After breast augmentation with autologous fat injection, irregular low-density small cyst-like shadow in the breast, granular, soybean to peanut rice size, surrounded by clearer, less uniform calcification shadow can be seen at the edge. Clinical symptoms such as pain and discomfort are often present. The timing of the onset of symptoms may vary from one individual to another. On mammography, fat necrosis may appear as punctate or irregular calcifications, which need to be differentiated from calcifications caused by breast cancer, and can be further observed by MR dynamic enhancement scan. The main complications of silicone gel prosthesis implantation are hematoma, fiber contracture, rupture, etc. True prosthesis rupture will appear as a signal shadow such as subperitoneal line, silicone mass or free silicone, “tongue sign” and “orbit sign”. Four years after silicone prosthesis placement, the T2-tirm sequence shows intracapsular rupture of the right prosthesis, with the “filament sign” (arrow). 7 years after silicone prosthesis placement, T2-tirm sequence, intracapsular rupture of the left prosthesis and intra- and extracapsular rupture of the right prosthesis, with some prosthetic signal outside the fibrous capsule (arrows). Polyacrylamide hydrogel injection: the number and morphology of hydrogel prostheses injected into the breast were classified as intact masses and multiple irregular free masses. Incomplete prosthetic envelope, see round, ovoid or irregular shaped prosthetic signal free in the posterior breast space and beyond, such as subcutaneous breast, within the breast parenchyma, axillary, under the fascia of the pectoralis major muscle, the continuity of the pectoralis major muscle can be interrupted. Nine years after double breast augmentation, T2-tirm sequence, double breast augmentation, silicone implant placement is seen in the posterior breast space with a slightly wrinkled envelope (white arrow), hydrogel injection is seen in the pectoralis major muscle, and muscle fiber discontinuity (red arrow). MRI shows a complete mass or scattered mass-like fat signal shadow in the posterior part of the breast parenchyma or within the breast parenchyma, with low-signal fiber separation in some parts, and no significant enhancement of the autologous fat on dynamic enhancement scan. The formation of “lipid planes” on MR images suggests liquefaction of the fatty fibrous mass, and internal signal heterogeneity and enhancement suggest partial liquefaction and necrosis of the transplanted fat. Ten years after the autologous fat transplantation, the T2-FS sequence showed dotted lamellar high signal in the lower part of the transplanted autologous fat mass, and enhancement was seen in the periphery and inside (arrows), which combined with the clinical diagnosis of partial necrosis of the transplanted fat with granuloma-like reaction. After silicone breast augmentation, the implant was removed for autologous fat augmentation due to contracture of the envelope. Preoperatively (left), the patient’s left implant was displaced upward due to contracture of the envelope; 12 months after surgery (right), T1-weighted MRI showed that the transplanted fat was surviving well. Mammogram shows no calcification or other abnormalities after fat grafting. The postoperative fat augmentation showed that the breast volume after removal of the implant was still acceptable, natural in shape, soft to the touch, and without nodules or sclerosis.