## 1 Introduction  
Osteochondritis dissecans (OCD) of the distal humerus is a significant cause of throwing elbow disorders in youth baseball players [1, 2]. The incidence of OCD ranges from 0.3% to 3.4%, with the most common age of onset being 10 to 12 years. Baseball pitching can produce excessive stress on the anterior part of the capitellum, where most OCD lesions in throwing athletes are found. Mechanical conditions may play a role in elbow OCD, and bone bruises may be a precursor to an OCD lesion [3]. In the early stages of OCD, symptoms are infrequent, and conservative treatment is usually effective. However, as the disease progresses, patients may experience elbow pain and twitching, necessitating prolonged sports cessation. In some cases, surgical intervention, such as the removal of free bone fragments or osteochondral grafting, may be required to prevent future osteoarthritis. According to the systematic review from [PERSON] et al. in 2021, nonoperative treatment was similar in outcomes to surgical treatment for low-grade lesions, whereas surgical treatment was superior for higher-grade lesions. There was no significant difference in the magnitude of improvement or overall scores according to the type of surgery for stable or unstable lesions [4]. Therefore, early detection of OCD is critical for successful conservative treatment. Imaging techniques such as radiography, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) are used to detect OCD. The age of diagnosis for capitellar OCD varies, and the appearance of the lesion depends on its stage. Careful evaluation using radiography, CT, MRI, and US is important for choosing the appropriate treatment. In recent years, improvements in US spatial resolution have enabled more detailed cross-sectional imaging of OCD in the elbow joint, even in asymptomatic patients [5]. US imaging is a rapid, inexpensive, and non-invasive tool that can evaluate both dominant and non-dominant elbows. In 2018, [PERSON] et al. reported the high accuracy of US imaging for OCD diagnosis [6]. The study compared the diagnostic accuracies of US and magnetic MRI with intraoperative OCD fragment-stability findings. They found that US was a useful tool for evaluating fragment instability in OCD and achieved superior accuracy compared with MRI criteria (96% vs. 73%). US screening for OCD is essential for early detection and successful conservative treatment. Group examinations such as the \"Medical Checkup for Baseball Elbow\" have been conducted nationwide for the early detection of OCD. In 2016, [PERSON] et al. reported that about 30% of youth baseball players had episodes of elbow pain and 4% of young baseball players had an abnormal finding at an initial ultrasonography screening [7]. In 2022, [PERSON] et al. reported a study of car-mounted mobile MRI for the on-field screening of OCD in young baseball players. Mobile MRI had a higher sensitivity than the US and could detect OCD from early stages to healing [8]. However, not all baseball teams have access to mobile MRI, and screening by US is currently more practical. Group examination of several teams at sports fields can lead to the detection of OCD in its early stages, when symptoms have not yet appeared, and can help to educate players, instructors, and parents. However, there are limitations to the diagnosis of OCD by US images, including operator dependency, the need for training, and interobserver variability in obtaining standardized measurements [5]. In recent years, artificial intelligence (AI), particularly deep learning (DL), has shown promise in addressing the limitations of US imaging. Convolutional neural networks (CNNs) have been widely studied for image analysis tasks, including medical image analysis [9]. DL has also been applied to US imaging studies, where it has shown promise in US imaging for musculoskeletal diseases.