紺野 啓

This report presents a case of malignant melanoma in a 40-year-old male who underwent resection of the tumor in his right ankle. Eleven months after the resection, a subcutaneous mass was observed on his right femur. Ultrasound examination revealed a hypoechoic tubular structure in the right thigh, with a small amount of blood flow in the lesion. Using ultrasound and fine-needle aspiration, the patient was diagnosed with metastasis and lymphovascular invasion of malignant melanoma. Treatment with an immune checkpoint inhibitor was originally scheduled, but the lesion disappeared spontaneously after the fine-needle aspiration.

PURPOSE: Fine-needle aspiration cytology (FNAC) under ultrasound guidance is clinically useful, but there is a risk of spreading infection by generating droplets of contaminated fluids during the procedure. Risk assessment to better control infection remains to be established. The aim of this study was to estimate infection risks during FNAC by visualization of droplet production and deposition using a simulation model. METHODS: The simulation comprised a puncture needle, a device for holding the needle, and a fluid specimen containing fluorescent particles as a model. Simulating each step of FNAC (removal of the inner and outer cylinder and transferring the specimen onto a glass slide), the generation and deposition of droplets were visualized using a laser. RESULTS: After removal of the inner cylinder, an aerosol of droplets in the air surrounding the needle was observed. After removal of the outer cylinder, several large droplets precipitating onto the circumjacent surface were observed. From the beginning of transferring the specimen, a large amount of sizeable droplets first moving away and then precipitating was observed, followed by the production of a cluster of fine droplets drifting and spreading through the air. CONCLUSIONS: Here, the generation of droplets at each step of FNAC, precipitation of large droplets onto the circumjacent surface, and drifting and spreading through the air of fine droplets was visualized. These results emphasize the need for precautions to prevent the transmission of infectious agents during FNAC.

PURPOSE: This study aimed to assess the feasibility and efficiency of self-learning with or without self-training (subjects performed scans on themselves) and telepresence instruction in focused cardiac ultrasound (FOCUS) education for medical students. METHODS: This study included 24 medical students. The participants initially completed a written pre-test and were randomized into a video lecture (participants watched a video lecture) or self-training (participants watched a video lecture and self-performed FOCUS) group. After finishing self-learning, they completed a written post-test. Then they undertook a skill pre-test and a first perception survey. Telepresence instruction was then provided. Finally, they undertook a skill post-test and a second perception survey. RESULTS: The written post-test total scores were significantly higher than the pre-test total scores (P < 0.001). In the skill pre-test, the scores for the video lecture and self-training groups were not significantly different (P = 0.542). The skill post-test total scores were significantly higher than the skill pre-test total scores (P = 0.008). Forty-two percent of the video lecture group participants agreed that the video lecture was effective preparation for the skill pre-test, while all participants in the same group agreed that the combination of the video lecture and telepresence instruction was effective preparation for the skill post-test. CONCLUSION: This study demonstrated the feasibility and efficiency of self-learning followed by telepresence instruction on FOCUS for medical students.

The concept of point-of-care ultrasound has been widely accepted owing to the development of portable ultrasound systems and growing body of evidence concerning its extensive utility. Thus, it is reasonable to suggest that training to use this modality be included in undergraduate medical education. Training in ultrasonography helps medical students learn basic subjects such as anatomy and physiology, improve their physical examination skills, and acquire diagnostic and procedural skills. Technological advances such as simulators, affordable handheld devices, and tele-ultrasound systems can facilitate undergraduate ultrasound education. Several reports have indicated that some medical schools have integrated ultrasound training into their undergraduate medical curricula. Jichi Medical University in Japan has been providing medical students with ultrasound education to fulfill part of its mission to provide medical care to rural areas. Vertical integration of ultrasound education into a curriculum seems reasonable to ensure skill retention and improvement. However, several issues have hampered the integration of ultrasound into medical education, including a lack of trained faculty, the need to recruit human models, requisition of ultrasound machines for training, and limited curricular space; proposed solutions include peer teaching, students as trained simulated patients, the development of more affordable handheld devices, and a flipped classroom approach with access to an e-learning platform, respectively. A curriculum should be developed through multidisciplinary and bottom-up student-initiated approaches. Formulating national and international consensuses concerning the milestones and curricula can promote the incorporation of ultrasound training into undergraduate medical education at the national level.