Pediatric liver transplantation is an important medical treatment that can save the life of a child with end-stage liver disease. Organ transplants began in the 1950s and took a new turn in 1963 with the first pediatric liver transplant in Denver, USA. However, the initial success rate was unsatisfactory due to technical difficulties and lack of immunosuppressive treatment. Later, introduction of immunosuppressants such as cyclosporine and tacrolimus improved the success rate, and pediatric liver transplants became widely available. This manuscript describes the history, current situation, issues, and future prospects for pediatric liver transplantation in Japan.

This study examined the significance of minimizing psychological stress and managing patient movement during radiological examinations in pediatric patients. These procedures frequently induce anxiety in children owing to factors such as the intimidating size of the equipment, loud operational noises, and the administration of radiopharmaceuticals, which can compromise the accuracy and effectiveness of the examination. To reduce reliance on sedation, which carries associated risks, strategies such as family presence, visual distraction techniques, and physical restraint have proven to be effective in maintaining patient stiffness. Preparation plays a vital role in alleviating anxiety by familiarizing the children with the procedure. This may involve using models or images to explain the process, introducing patients to the sounds of the equipment, and employing age-appropriate tools, such as videos or medical picture books. By reducing stress and promoting understanding, these measures not only enhance the quality and reliability of examinations, but also contribute to improved clinical outcomes.

A Precise IQ Engine (PIQE) was developed as a reconstruction technology for magnetic resonance imaging (MRI). This is a Deep Learning Reconstruction (DLR) method developed using deep learning technology (DLT), which belongs to the field of artificial intelligence (AI). Using this PIQE for image processing, a high-resolution image can be obtained within a short time. The fact that imaging can be performed within a short time makes it possible to perform MRI examinations even in children who tend to be uncooperative. It is also possible to image fetuses who are only a few weeks old and are prone to movement during imaging. High resolution also makes it possible to image the details of the lesions of small organs in both children and fetuses.

This review presents precautions and tips for interpreting fetal magnetic resonance imaging (MRI) findings for left diaphragmatic hernia (CDH), congenital pulmonary airway malformation (CPAM), esophageal atresia, pulmonary sequestration, and congenital high airway obstruction syndrome (CHAOS). Furthermore, we introduce fetal MRI studies conducted at the authors’ facilities along with paper reports. In CDH and CPAM, the evaluation of mediastinal deviation is necessary, and the measurement of the MSA is helpful. Dynamic observation using cine mode imaging is useful for diagnosing esophageal atresia. Imaging using the SSTSE method is indispensable for diagnosing pulmonary sequestration. We also discuss methods for the diagnosis and measurement of CHAOS with an esophagotracheal fistula. Appropriate examinations and imaging interpretation are necessary for making a fetal MRI diagnosis.

Fetal CT is the next best examination after ultrasonography for the diagnosis of fetal skeletal dysplasia because it can easily visualize the entire skeleton. Advances in CT devices have made it possible to visualize the fetal skeleton, even with considerably reduced radiation doses. However, CT cannot reduce the radiation dose to zero. Therefore, we wondered whether it would be possible to evaluate the fetal skeleton using MRI without radiation exposure, and thus conducted a study to compare the bone depiction between MRI and CT using fetal specimens stored at our facility. Our findings demonstrated that it was difficult to evaluate the entire fetal skeleton using 3D imaging with the current MRI system. However, there are several reports on fetal bone morphology evaluation using the MRI gradient echo (GRE) method. In addition, MR bone images (CT-like images) have also recently been applied in the clinical setting. Depending on further advances in MRI methods, in the future MRI may replace CT in the diagnosis of fetal skeletal dysplasia.

The application of cardiovascular MRI to fetal cardiovascular imaging is compelling, and clinical imaging has been implemented in Western countries for over 20 years. However, when attempting to acquire fetal cardiovascular data using conventional cardiovascular MRI methods, numerous limitations arise: the fetal heart is small with a high heart rate, conventional cardiac gating is difficult due to inability to monitor fetal electrocardiogram, and there are challenges with maternal breathing and unpredictable fetal movement. In recent years, fetal cardiovascular MRI has made significant technical advances, progressing from single-shot imaging to high-resolution dynamic imaging, enabling visualization of fetal cardiovascular anatomical structures, quantification of blood flow, and measurement of blood oxygen saturation and hematocrit values. This paper discusses the technological innovations that have made dynamic MRI imaging of the fetal cardiovascular system possible, including the development of fetal ECG acquisition techniques, accelerated imaging technology, and improvements in motion correction algorithms. It also provides an overview of how fetal congenital heart disease affects fetal hemodynamics.

Fetal therapy should be performed for diseases that progress prenatally and result in fetal death or disability, ensuring that the benefits of treatment outweigh the risks associated with maternal and fetal invasiveness, or preterm delivery. Current fetal treatments are categorized according to their level of invasiveness into transplacental pharmacotherapy, ultrasound-guided procedures, fetoscopic surgery, and open surgery. Fetoscopic laser photocoagulation for twin-to-twin transfusion syndrome and fetoscopic endoluminal tracheal occlusion for congenital diaphragmatic hernia have been evaluated in randomized controlled trials primarily conducted in Europe. In the United States, open fetal surgery for myelomeningocele has been evaluated in a randomized controlled trial. In Japan, fetal thoracoamniotic shunting for fetal hydrothorax has been approved and covered by National Health Insurance following clinical trials. Additionally, clinical trials of open surgery to treat myelomeningocele and fetal aortic valvuloplasty for severe aortic stenosis are currently underway in Japan.

There are many types of contrast agents, which have long been indispensable in daily medical practice. Although the use of contrast agents often adds useful information to imaging examinations, their use is associated with certain risks, and the intended use of each contrast agent is determined. To perform examinations safely and obtain the maximum benefit, it is necessary to consider the necessity of using contrast agents and correctly understand contraindications and important precautions for use. Therefore, it is important to regularly update important information on the safety of contrast agents and update related knowledge. In this article, we focus on iodine contrast agents used in CT and gadolinium contrast agents used in MRI, as well as basic matters such as indications for contrast agent use, precautions to take when using contrast agents, and risks such as side effects. We also discuss precautions specific to children and the concept of using contrast agents.

Fluid-attenuated inversion recovery (FLAIR) has become a routine sequence for head imaging in many facilities in daily clinical practice. FLAIR uses inversion pulses to suppress the signals of physiological water components in the cranial cavity, making it easier to detect T2 prolongation lesions. However, various factors can cause high signals in the cerebral sulci on FLAIR images. The main factors include increased protein concentration, presence of hemorrhagic components, elevated cellular components (including tumor and inflammatory cells), and artifacts, which leads to a wide range of differential diagnoses. When evaluating FLAIR images, it is important to consider these factors and to incorporate clinical information into the diagnostic process.

Gorham-Stout disease (GSD) is a rare disease characterized by progressive osteolysis with abnormal lymphovascular proliferation. We herein report a pediatric case of GSD presenting with progressive bone absorption of the skull without local symptoms. A three-year-old boy with no remarkable history had a depressive lesion of the forehead at the three-year medical checkup. The number of depressive lesions increased over the next seven months. Computed tomography (CT) of the head revealed osteolysis of the frontal bone without soft tissue involvement, osteosclerosis, or periosteal reaction. Magnetic resonance imaging (MRI) revealed multiple hyperintense lesions on T2 fat-suppression imaging of the skull, vertebrae, pelvis, and femur. GSD was diagnosed by confirming abnormal lymphovascular invasion in a bone biopsy of the occipital bone. Owing to the concomitant cerebrospinal fluid leak leading to Chiari malformation type I, sirolimus, an oral mammalian target of rapamycin inhibitor (mTOR), was initiated to avoid major neurological complications by spiral cord compression. At the 20-month follow-up, sirolimus achieved stability in all altered intensity lesions on MRI. Prompt and detailed radiological examinations are needed to differentiate GSD from other pediatric osteolytic diseases and to assess the risk of complications due to affected bone lesions.