[in Japanese]

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[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

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Digital breast tomosynthesis (DBT) has the advantage of better depiction of findings as it allows for a reduced overlap by the background mammary gland as compared to the case in conventional mammography, but it also shows specific contrast changes and artifacts. In this study, we examined whether the contrast of the reconstructed images in DBT differs depending on the direction of movement of the x-ray tube, assuming the form of a cord-like shadow expanding in different directions, or distortion. We found that the contrast of structures perpendicular to the x-ray tube movement direction appears stronger in the reconstructed images in DBT, suggesting that the image reconstruction method exerts a great influence, which should be borne in mind, as it could lead to misdiagnosis.

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We constructed a database of mammograms obtained with five commercial full-field digital mammography (FFDM) systems at four institutions. The aim of this research was to compare the thickness of the compressed breasts between the mediolateral oblique (MLO)- and craniocaudal (CC)-view images of 2,772 mammograms obtained from 807 patients in the database. The average compressed breast thickness in the MLO-view images was less than that in the CC-view images (42.50 mm vs. 44.11 mm, p<0.001) despite the greater force used to compress the breast for obtaining the MLO-view images than for obtaining the CC-view images (92.44 vs.89.38 newtons, p<0.01).

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It is generally accepted that ultrasound (US) is a useful examination to detect normal and abnormal lymph nodes in patients with breast cancer. Although normal or reactive level I lymph nodes can be detected by US, no consensus has been reached about the usefulness of US to detect Level II lymph nodes. The purpose of this study was to evaluate the frequency of detection and nature of level II lymph nodes detected by US in healthy women and also to assess if the tool can be used for the diagnosis and treatment of breast cancer. A total of 5228 women underwent breast US as part of opportunistic breast cancer screening at our center from March to August 2018. The images included those of 5036 healthy women, excluding those who had a current or previous history of axillary lymph node metastasis. Routine screening US breast images were evaluated with regard to the frequency of detection of the lymph nodes and the characteristics of the detected lymph nodes. Level II lymph nodes were detected in 348 women (6.9%) and 490 lymph nodes were detected either unilaterally or bilaterally. The L/T ratio of the lymph nodes was less than 2.0 in 144 (29.4%) and greater than 2.2 in 346 (70.6%) nodes. Thus, approximately one-third of the subjects had lymph nodes with a round configuration. In conclusion, it should be kept in mind that normal or reactive lymph nodes can be detected by US in about 7% of healthy women.

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Breast cancer screening is being conducted by the municipal screening center and 14 individual medical institutions in Nishinomiya City, Hyogo Prefecture, Japan. We investigated the impact of variation in process indicators among the screening institutions on the results of screening. All of the process indicators of the city’s screenings during the past 10 years as a whole met the permissible values, and high-quality screening was being maintained. However, when we reviewed the process indicators according to the individual medical institutions, we found that not all of them had met the permissible values. We concluded that there is room for improvement on the basis of the process indicators in order to implement higher quality screenings in the future.

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A 51-year-old woman visited our clinic for detailed examination of a left breast mass that had been detected by screening mammography. The lesion, a left breast mass, was well-defined, with a smooth surface, on mammography. Ultrasonography also yielded the same findings. We finally diagnosed the left breast tumor as a fibroadenoma by vacuum-assisted biopsy (VAB). The mammography also showed a focal asymmetric density (FAD) in the right breast, but this FAD could only be visualized in the craniocaudal (CC)-view images on2D-mammography, but not in the mediolateral oblique (MLO)-view images, because in this view, it was indistinguishable from the background mammary gland. Therefore, such lesions could be missed by 2D-mammography. Since the patient's breasts were large and fatty, it was extremely difficult to detect the lesion byultrasonography. However, the lesion, which was spiculated, was seen in both the CC-and MLO-view images of digital breast tomosynthesis (DBT). Since the findings of DBT suggested malignancy, we were able to confidently add specific examinations and make the diagnosis of breast cancer.

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A 67-year-old woman was admitted to our department with suspected left breast cancer. She had a past history of undergoing bilateral mammoplasty using silicone implants in her thirties. Computed tomography showed multiple curvilinear floating lines in the silicone implant on the left side, which is known as the linguine sign, and indicates complete collapse of the implant shell. Ultrasonography of the left breast at the first consultation showed the stepladder sign, which is represented by multiply folded shells floating in silicone gel. Since the patient was also diagnosed as having stage1 breast cancer, a partial mastectomy with sentinel lymph node biopsy was performed, followed by bilateral breast implant removal. When the fibrous capsule in the left breast was released, viscous silicone gel with some torn pieces of shell were drained, whereas the right breast implant was intact. Histopathologically, no piece of silicone was found in the resected breast tissue or lymph nodes. Breast implant rupture is classified as intracapsular or extracapsular. Since intracapsular rupture usually occurs without apparent symptoms, it is often detected by chance during radiological studies, as in this case. Surgical removal of the silicone gel in these cases is not so difficult. On the other hand, in the case of extracapsular rupture, silicone gel invading the breast parenchyma and lymphatics causes several inflammatory changes, and total removal of the silicone is nearly impossible. It is essential to diagnose implant rupture as early as possible by breast imaging studies. Since several diagnostic images typical of implant rupture have been reported in the literature, a breast physician should be familiar with these changes for early diagnosis.

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