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Leg length discrepancy (LLD) is a common problem that can cause long-term musculoskeletal problems. However, measuring LLD on radiography is time-consuming and labor intensive, despite being a simple task.To develop and evaluate a deep-learning algorithm for measurement of LLD on radiographs.In this Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study, radiographs were obtained to develop a deep-learning algorithm. The algorithm developed with two U-Net models measures LLD using the difference between the bilateral iliac crest heights. For performance evaluation of the algorithm, 300 different radiographs were collected and LLD was measured by two radiologists, the algorithm alone and the model-assisting method. Statistical analysis was performed to compare the measurement differences with the measurement results of an experienced radiologist considered as the ground truth. The time spent on each measurement was then compared.Of the 300 cases, the deep-learning model successfully delineated both iliac crests in 284. All human measurements, the deep-learning model and the model-assisting method, showed a significant correlation with ground truth measurements, while Pearson correlation coefficients and interclass correlations (ICCs) decreased in the order listed. (Pearson correlation coefficients ranged from 0.880 to 0.996 and ICCs ranged from 0.914 to 0.997.) The mean absolute errors of the human measurement, deep-learning-assisting model and deep-learning-alone model were 0.7 ± 0.6 mm, 1.1 ± 1.1 mm and 2.3 ± 5.2 mm, respectively. The reading time was 7 h and 12 min on average for human reading, while the deep-learning measurement took 7 min and 26 s. The radiologist took 74 min to complete measurements in the deep-learning mode.A deep-learning U-Net model measuring the iliac crest height difference was possible on teleroentgenograms in children. LLD measurements assisted by the deep-learning algorithm saved time and labor while producing comparable results with human measurements.

Background To describe the radiological features of Gorham–Stout disease (GSD) as evaluated using plain radiography and dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL) imaging techniques. Methods Clinical and conventional imaging data were retrospectively reviewed for 15 patients with GSD between January 2001 and December 2020. After December 2018, DCMRL examinations were performed for lymphatic vessel evaluation in patients with GSD and reviewed in four patients. Results The median age at diagnosis was 9 years (range: 2 months–53 years). The clinical manifestations were dyspnea in seven patients (46.7%), sepsis in 12 (80.0%), orthopedic problems in seven (46.7%), and bloody chylothorax in seven (46.7%). The common sites of osseous involvement were the spine (73.3%) and pelvic bone (60.0%). Among the non-osseous involvements, peri-osseous infiltrative soft-tissue abnormalities adjacent to the area of bone involvement were the most common (86.7%), followed by splenic cysts (26.7%) and interstitial thickening (26.7%). DCMRL demonstrated weak central conducting lymphatic flow in two patients with abnormal giant tortuous thoracic ducts and no flow in one patient. All patients who underwent DCMRL in this study presented with altered anatomical lymphatics and functional flow with collateralization. Conclusion DCMRL imaging and plain radiography are very useful for determining the extent of GSD. DCMRL is a novel imaging tool for the visualization of abnormal lymphatics in patients with GSD, which helps in further treatment. Therefore, in patients with GSD, it might be necessary to obtain not only plain radiographs but also MR and DCMRL images.

To develop an automatic segmentation algorithm using a deep neural network with transfer learning applicable to whole-body PET-CT images in children.For model development, we utilized transfer learning with a pre-trained model based on adult patients. We used CT images of 31 pediatric patients under 19 years of age (mean age, 9.6 years) who underwent PET-CT from institution #1 for transfer learning. Two radiologists manually labeled the skin, bone, muscle, abdominal visceral fat, subcutaneous fat, internal organs, and central nervous system in each CT slice and used these as references. For external validation, we collected 14 pediatric PET/CT scans from institution #2 (mean age, 9.1 years). The Dice similarity coefficients (DSCs), sensitivities, and precision were compared between the algorithms before and after transfer learning. In addition, we evaluated segmentation performance according to sex, age (≤ 8 vs.8 years), and body mass index (BMI, ≤ 20 vs.20 kg/mThe algorithm after transfer learning showed better performance than the algorithm before transfer learning for all body compositions (p0.001). The average DSC, sensitivity, and precision of each algorithm before and after transfer learning were 98.23% and 99.28%, 98.16% and 99.28%, and 98.29% and 99.28%, respectively. The segmentation performance of the algorithm was generally not affected by age, sex, or BMI, except for precision in the body muscle compartment.The developed model with transfer learning enabled accurate and fully automated segmentation of multiple tissues on whole-body CT scans in children.• We utilized transfer learning with a pre-trained segmentation algorithm for adult to develop an algorithm for automated segmentation of pediatric whole-body CT. • This algorithm showed excellent performance and was not affected by sex, age, or body mass index, except for precision in body muscle.

Juvenile xanthogranuloma (JXG) is a type of non-Langerhans cell histiocytosis that most commonly manifests as a solitary cutaneous lesion of the head and neck in children. Intracranial JXG is extremely rare. Although it is widely known that JXG skin lesions gradually disappear over time without treatment, treatment guidelines for intracranial JXG have not been established. It is very difficult to predict whether an intracranial lesion is JXG with only a pre-operative imaging work-up without pathologic confirmation. We report a case of the youngest, a 3-month-old male infant with an intracranial extra-axial mass with rapid growth for 2 months. Additionally, we suggest characteristic MRI findings for intracranial extra-axial JXG of a low T2 signal and a kidney bean shape.

A cerebral arteriovenous malformation (AVM) is a congenital and static disease. However, there are increasing reports of acquired AVMs. The pathophysiology of an acquired AVM has not been fully elucidated but the suggested pathophysiology is a combination of genetic abnormalities and inflammatory cytokines caused by previous brain insults. We report a patient who developed an acquired AVM after the treatment for a brain abscess. She underwent Gamma Knife surgery to treat the acquired AVM. It is necessary to understand the characteristics of acquired AVMs and to further research acquired AVMs.

Preoperative estimation of the insertion depth angle of cochlear implant (CI) electrodes is essential for surgical planning. The purpose of this study was to determine the cochlear size using preoperative CT and to investigate the correlation between cochlear size and insertion depth angle in morphologically normal cochlea. Thirty-five children who underwent CI were included in this study. Cochlear duct length (CDL) and the diameter of the cochlear basal turn (distance A/B) on preoperative CT and the insertion depth angle of the CI electrode on postoperative radiographs were independently measured by two readers. Correlation between cochlear size and insertion depth angle was evaluated. Interobserver agreement was calculated using the intraclass correlation coefficient (ICC). The mean CDL, distance A, and distance B of 70 ears were 36.20 ± 1.57 mm, 8.67 ± 0.42 mm, and 5.73 ± 0.32 mm, respectively. The mean insertion depth angle was 431.45 ± 38.42°. Interobserver agreements of CDL, distance A/B, and insertion depth angle were fair to excellent (ICC 0.864, 0.862, 0.529, and 0.958, respectively). Distance A (r = − 0.7643) and distance B (r = − 0.7118) showed a negative correlation with insertion depth angle, respectively (p 0.05). The CDL and cochlear distance can be reliably obtained from preoperative CT. Distance A can be used as a predictive marker for estimating insertion depth angle during CI surgery.

To evaluate the clinical usefulness of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in children and young adults with Crohn’s disease. From August 2017 to October 2018, 30 patients with Crohn’s disease (21 males and 9 females; mean age 15.1 ± 2.5 years) underwent DCE-MRI with MRI enterography. We assessed the endoscopic finding, pediatric Crohn’s disease activity index (PCDAI), C-reactive protein (CRP) level (mg/dL), Crohn’s disease MR index (CDMI) score, and the perfusion parameters of DCE-MRI (Ktrans, Kep, and Ve) at the ileocecal region between the inactive and active groups based on the histopathologic status. The active Crohn’s disease group showed higher PCDAI, CRP, and CDMI scores than the inactive group (22.2 ± 18.8 vs. 6.3 ± 6.4, p = 0.027; 1.32 ± 1.79 vs. 0.10 ± 0.13, p = 0.005; 7.4 ± 3.9 vs. 4.5 ± 3.0, p = 0.047, respectively). The active Crohn’s disease group showed a higher Ktrans value than the inactive group (0.31 ± 0.12 vs. 0.16 ± 0.46 min−1, p = 0.002). Endoscopic finding; PCDAI, CRP, and CDMI scores; and Ktrans value were significant parameters in the identification of the active Crohn’s disease (p = 0.002, p

Background Central nervous system germ cell tumors (CNS GCTs) are a heterogeneous group of brain tumors, which are more common in Asian countries. There have been different therapeutic strategies in treating germinoma and non-germinomatous germ cell tumors (NGGCT), depending on prognosis. Moreover, long-term follow up should be emphasized due to higher late complication rates. Here, we investigated long-term outcomes and complication profiles of 127 CNS GCT patients who received uniform upfront chemotherapy. Methods We retrospectively evaluated outcomes of CNS GCT patients treated in Seoul National University Children’s Hospital from August 2004 to April 2019. Patients were classified as low risk (LR) or high risk (HR) based on pathologic diagnosis and tumor markers. Most patients received upfront systemic chemotherapy with carboplatin, cyclophosphamide, etoposide, and/or bleomycin, followed by either proton or photon radiation therapy according to patients’ choice. Results The median age at diagnosis was 11.9 (range, 3.8–25.1) years, and 54.3% of patients were LR. Photon and proton radiation therapy were administered to 73.2 and 25.2% of patients, respectively. In both LR and HR groups, there were no significant differences in survival between photon and proton radiation therapy. The 10-year relapse incidences were 9.3 and 5.6% in the LR and HR groups, respectively. All recurrences, except one, were local relapse. Six secondary malignancies occurred; the 10-year incidences of secondary malignancy were 2.2 and 7.6% in the LR and HR groups, respectively. The 10-year overall survival rates were 98.3 ± 1.7 and 91.8 ± 3.9% in the LR and HR groups, respectively. In a subgroup analysis of HR group, pathologically diagnosed NGGCT patients (n = 20) showed worse 10-year EFS (65.9 ± 11.9%, p p = 0.024) rates compared to other HR patients who were not pathologically diagnosed or were confirmed as germinoma with elevated tumor markers. All mortalities were related to disease progression or secondary malignancy. Conclusion The strategy of treating CNS GCTs with upfront chemotherapy according to risk groups resulted in good clinical outcomes and acceptable relapse incidence. However, further modification in the definition of the HR group is needed to reduce long-term complications.

Toxicity of carmustine and cyclophosphamide can cause pulmonary injury after hematopoietic stem cell transplantation. To evaluate the radiologic findings of pulmonary injuries following carmustine- and cyclophosphamide-based preparative regimens in children. From 2010 to 2014, 35 children received carmustine- and cyclophosphamide-based preparative regimens. Fourteen of 35 children presented with symptoms and radiologic abnormalities. Eight of 14 children had no evidence of infection, cardiogenic edema, or other explainable causes. We retrospectively analyzed their chest radiographs and CT scans for ground-glass opacity, consolidation, septal thickening and pleural effusion. Major chest radiographic findings were bilateral diffuse ground-glass opacity (n=8) and septal thickening (n=7). CT findings were multifocal patchy (n=4) or inhomogeneously diffuse (n=4) ground-glass opacity, multifocal consolidations (n=7) and septal thickening (n=7). All of these lesions at CT were bilateral, but showed lower lobe predominance in 88, 100, and 63%, respectively. There was no central/peripheral or anterior/posterior predilection. Six children had small pleural effusions, which were bilateral in five children. Bilateral ground-glass opacity with or without consolidation, septal thickening and pleural effusion were common radiologic findings in pulmonary injury following carmustine- and cyclophosphamide-based preparative regimens.

Intracranial neurenteric cysts are rare and are not often found in the supratentorial space. We present a case of an intracranial neurenteric cyst that arose at the suprasellar cistern with extension to the middle cranial fossa. A 3-year-old girl presented with seizure. Neuroimaging showed a huge extra-axial cyst involving the suprasellar cistern and left middle cranial fossa. Under the impression of an arachnoid cyst, she underwent fenestration of the cyst with basal cisterns and ventricle. The pathologic diagnosis was neurenteric cyst. Four years after the surgery, MRI showed no recurrence but did show poorly developed myelination of the left temporal white matter. Three years after surgery, seizures recurred. We consider epilepsy surgery in case of uncontrolled seizure. We discuss the unique case of supratentorially located neurenteric cyst that is just treated by fenestration. A close follow-up is needed for children with intracranial neurenteric cysts to surveil not only recurrence of lesion but also normal brain development.

To evaluate the predictive value of ultrasonography in children with clinically suspicious hepatic veno-occlusive disease (VOD) after hematopoietic stem cell transplantation (HSCT). Among 216 children who underwent HSCT, 70 also underwent colour Doppler ultrasonography. Of these, 59 had only one sign/symptom, which did not fulfil the diagnostic criteria (clinical suspicion of VOD) at that time. VOD was confirmed in 20 patients (VOD group), while 39 had other conditions (non-VOD group). The following findings were reviewed and compared between groups: left portal vein (peak velocity, direction), left hepatic artery (peak-systolic/end-diastolic velocities, resistive index), middle hepatic vein (peak velocity, phasicity), hepatomegaly, splenomegaly, gallbladder wall thickness, and ascites. The VOD group showed significantly higher reversed flow in portal vein (P = 0.011), peak systolic velocity of left hepatic artery (P = 0.028), monophasicity of middle hepatic vein (P = 0.015), hepatomegaly (P = 0.001), gallbladder wall thickness (P

Benign extracerebral fluid collection (bECFC) can be complicated by subdural hematoma (SDH) or subdural fluid collection (SDFC). The etiology, natural history, and management strategy for SDH/SDFC in bECFC are not fully understood. We retrospectively reviewed the cases of bECFC patients complicated with SDH/SDFC and tried (1) to confirm the fact that bECFC children are vulnerable to SDH/SDFC, (2) to investigate the clinical significance of 'trauma history' witnessed by a caregiver, and (3) to determine optimal management for them. Among 213 bECFC patients identified from January 2000 to August 2015, 20 patients (male:female = 14:6; median age, 6.5 months; range 1–16 months) complicated by SDH/SDFC documented with brain imaging were evaluated for their clinical manifestations, radiologic features, and management outcomes. The median follow-up period was 9.5 months. They were divided into two groups (traumatic group versus non-traumatic group) according to whether objective radiologic evidence of head injury was present or not, and the two groups were analyzed for any clinical differences between them. We also evaluated the clinical significance of witnessed traumatic events by caregivers as an additional independent variable in the analysis. The incidence of SDH/SDFC in bECFC patients was 9.4% (20/213) in our data. In a comparative analysis, the traumatic group is more likely to have 'acute' stage SDH, whereas the non-traumatic group is more likely to have 'chronic' stage SDH. The trauma history witnessed by caregivers did not show clinical significance in the data analysis when included as an independent variable. The prognosis of SDH/SDFC in bECFC patients was favorable without surgery in most of patients regardless of whether the patient has evidence of head trauma or not. Benign ECFC is vulnerable to SDH/SDFC development. For the bECFC patients complicated by SDH/SDFC, the trauma history witnessed by a caregiver did not show any clinical significance. A 'wait and watch' strategy is sufficient for the management of SDH/SDFC in bECFC patients.

The clinical application of the multi-echo, multi-delay technique of synthetic magnetic resonance imaging (MRI) generates multiple sequences in a single acquisition but has mainly been used in adults. To evaluate the image quality of synthetic brain MR in children compared with that of conventional images. Twenty-nine children (median age: 6 years, range: 0–16 years) underwent synthetic and conventional imaging. Synthetic (T2-weighted, T1-weighted and fluid-attenuated inversion recovery [FLAIR]) images with settings matching those of the conventional images were generated. The overall image quality, gray/white matter differentiation, lesion conspicuity and image degradations were rated on a 5-point scale. The relative contrasts were assessed quantitatively and acquisition times for the two imaging techniques were compared. Synthetic images were inferior due to more pronounced image degradations; however, there were no significant differences for T1- and T2-weighted images in children

Computed tomography (CT) has generated public concern associated with radiation exposure, especially for children. Lowering the tube voltage is one strategy to reduce radiation dose. To assess the image quality and radiation dose of non-enhanced brain CT scans acquired at 80 kilo-voltage peak (kVp) compared to those at 120 kVp in children. Thirty children who had undergone both 80- and 120-kVp non-enhanced brain CT were enrolled. For quantitative analysis, the mean attenuation of white and gray matter, attenuation difference, noise, signal-to-noise ratio, contrast-to-noise ratio and posterior fossa artifact index were measured. For qualitative analysis, noise, gray-white matter differentiation, artifact and overall image quality were scored. Radiation doses were evaluated by CT dose index, dose-length product and effective dose. The mean attenuations of gray and white matter and contrast-to-noise ratio were significantly increased at 80 kVp, while parameters related to image noise, i.e. noise, signal-to-noise ratio and posterior fossa artifact index were higher at 80 kVp than at 120 kVp. In qualitative analysis, 80-kVp images showed improved gray-white differentiation but more artifacts compared to 120-kVp images. Subjective image noise and overall image quality scores were similar between the two scans. Radiation dose parameters were significantly lower at 80 kVp than at 120 kVp. In pediatric non-enhanced brain CT scans, a decrease in tube voltage from 120 kVp to 80 kVp resulted in improved gray-white matter contrast, comparable image quality and decreased radiation dose.

It is difficult to diagnosis early stage germ cell tumors originating in the basal ganglia, but early recognition is important for better outcome. To evaluate serial MR images of basal ganglia germ cell tumors, with emphasis on the features of early stage tumors. We retrospectively reviewed serial MR images of 15 tumors in 14 children and young adults. We categorized MR images of the tumors as follows: type I, ill-defined patchy lesions (

Primary melanocytic lesions of the central nervous system originate from leptomeningeal melanocytes, with a spectrum ranging from well-differentiated benign meningeal melanocytomas to malignant melanomas. Atypical melanocytomas are borderline tumors, which have clinical and pathological characteristics between benign melanocytomas and malignant melanomas. Melanocytomas are rare in children and infrequently arise from the cavernous sinus. Approximately five patients with such an origin site have been reported. We report a 15-year-old girl with an atypical melanocytoma arising from the cavernous sinus. She underwent partial resection of the tumor and postoperative gamma knife surgery (GKS). She is stable 39 months after surgery. We discuss the first pediatric case with an intracranial atypical melanocytoma arising from the cavernous sinus.

Introduction The location of a brain tumor is a fundamental characteristic, because various brain tumors develop in relatively specific locations. An atypical teratoid/rhabdoid tumor (AT/RT) is a highly age-specific tumor that occurs in infants and young children. However, AT/RTs develop in a variety of locations in the brain. This study aimed at uncovering the tumor location pattern of AT/RTs to enhance diagnoses. Material and methods Neuroimages from 27 patients with a pathologically proven AT/RTwere reviewed, and the specific tumor locations were described and categorized. The association of imaging characteristics and tumor location was analyzed. Results The posterior fossa was the most frequent locations accounting for 19 patients (70 %), followed by the diencephalon (four patients; 15 %), cerebrum (three patients; 11 %), and midbrain (one patient; 4 %). In the posterior fossa, the superior medullary velum (SMV) and cerebellopontine angle (CPA) areas were the most common sites (eight patients each) and three patients had a tumor in the inferior medullary velum (IMV) region. AT/RTs in the SMV area had a significantly higher chance of no/minimal enhancement compared with tumors in other locations (P=0.001) and a lower likelihood of leptomeningeal tumor seeding at presentation (P=0.053). Conclusion Thelocationspectrum of AT/RT follows a specific pattern, and some of the locations are linked with intriguing clinical characteristics. This information may not only help make correct preoperative diagnosis but also occasionally aid in postoperative pathological diagnosis.

Knowledge of the optimal lengths for central venous catheterization prior to the procedure may lessen the need for repositioning and prevent vascular complications. To establish the optimal lengths for non-tunneled central venous catheter insertion through the right and left internal jugular veins. We included 92 children who received US-guided central venous catheterization via right or left internal jugular veins in intensive care units. The calculated distance between the skin and carina was considered the optimal length for right and left internal jugular venous catheterization. Univariate and multivariate linear regression analyses was used to identify predictors. Age, height and weight showed significant correlations with optimal insertion lengths for right and left internal jugular vein approaches on univariate analysis, while height was the only significant independent predictor of optimal insertion length. The optimal insertion lengths (cm) suggested by our data are, for the right internal jugular vein 0.034 × height (cm) + 3.173, and for the left 0.072 × height (cm) + 2.113.

Radial k-space sampling techniques have been shown to reduce motion artifacts in adult abdominal MRI. To compare a T2-weighted radial k-space sampling MRI pulse sequence (BLADE) with standard respiratory-triggered T2-weighted turbo spin echo (TSE) in pediatric abdominal imaging. Axial BLADE and respiratory-triggered turbo spin echo sequences were performed without fat suppression in 32 abdominal MR examinations in children. We retrospectively assessed overall image quality, the presence of respiratory, peristaltic and radial artifact, and lesion conspicuity. We evaluated signal uniformity of each sequence. BLADE showed improved overall image quality (3.35 ± 0.85 vs. 2.59 ± 0.59, P

To decrease the negative appendectomy rate in children, knowledge of the misleading imaging findings on US and CT in negative appendicitis cases is important. To evaluate the negative appendectomy rate and describe the imaging findings of US and CT that lead radiologists to misdiagnose acute appendicitis in children. From 2007 to 2013, 374 children operated for suspected appendicitis were proved to either have acute appendicitis (n = 348) or to be negative for appendicitis (n = 26) on pathological reports. Negative appendectomy rates were compared among imaging modalities, age groups and genders. We retrospectively reviewed US and CT findings from negative appendectomy cases. The overall negative appendectomy rate was 7.0% (26/374). There were no statistically significant differences among the subgroups. The most common misleading presentations on US were sonographic tenderness (9/16, 56%) and non-compressibility (9/16, 56%). The most common misleading finding on CT were the presence of an appendicolith or hyperdense feces (5/12, 42%). Periappendiceal fat inflammation was observed in only one case of negative appendicitis on US and on CT. Radiologists can misdiagnose children with equivocal diameters of appendices as having acute appendicitis when sonographic tenderness or non-compressibility is present on US and when an appendicolith or hyperdense feces is noted on CT. The possibility of negative appendicitis should be borne in mind when periappendiceal fat inflammation is absent or minimal in indeterminate cases.

A 4-month-old boy presented with persistent gross hematuria. At ultrasonography, a 3.5-cm echogenic mass with posterior shadowing and tumor vascularity was detected within the right renal pelvis. Precontrast CT showed a slightly hyperattenuating mass in the renal pelvis. At MRI the mass was heterogeneously hypointense on T2-weighted images and isointense on T1-weighted images. Contrast-enhanced CT and MRI both revealed peripheral enhancement of the mass. A histological diagnosis of ossifying renal tumor of infancy was made after open pyelostomy and tumor enucleation. We suggest that ossifying renal tumor of infancy should be considered when a mass with posterior acoustic shadowing and tumor vascularity on US, hyperattenuation on precontrast CT and hypointensity on T2-weighted MRI is seen within the renal pelvis of an infant with hematuria.

Involuntary movement is a rare symptom of moyamoya disease (MMD). No consensus has been reached regarding its clinical features and pathogenetic mechanism. Therefore, pediatric MMD patients presenting with involuntary movement were retrospectively analyzed, focusing on the image findings. A total of 513 patients who were treated for MMD were reviewed. After exclusion of MMD syndromes and those with accompanying conditions related to involuntary movements, five patients (mean age: 11.6 years, range: 5–13 years) were evaluated. All of the patients improved their symptoms rapidly after the indirect bypass operations to the contralateral hemisphere. All remained symptom-free during the long follow-up period. Comprehensive evaluation of the preoperative imaging findings failed to suggest a characteristic feature in common, corresponding to the existing hypotheses or a new hypothesis. Only one patient showed infarction preoperatively, and only one patient showed prominently enhanced collateral vessels in the basal ganglia. Although a decrease in vascular reserve was observed in all patients, the location and laterality were nonspecific. There still appears to be confusion regarding the pathogenetic mechanism of involuntary movement in MMD with no repetitive, established imaging features to explain the phenomenon. Nonetheless, with its excellent response to surgical treatment, clinical awareness of this rare symptom of MMD should be emphasized as a differential diagnosis for secondary movement disorder in children.

The optimal treatment for Chiari I malformation in children is still under debate. The aim of this study was to evaluate the surgical outcome of the pediatric Chiari I malformation, focusing on clinico-radiological factors and technical aspects. Fifty-six patients with Chiari I malformation who received surgery at Seoul National University Children’s Hospital were included. The mean age was 7.9 years. The patients were divided into three groups: group I (n = 8) with hydrocephalus, group II (n = 11) without syrinx, and group III (n = 37) with syrinx. Group I received shunting operation initially, and others received foramen magnum decompression (FMD). Group III was further subdivided: group IIIa (n = 9), minimal intradural manipulation, and group IIIb (n = 27), active intradural manipulation. The outcomes were compared between the groups. The mean follow-up period was 75.9 months. In group I, symptoms were resolved or had improved in most patients, with only one patient received additional FMD. Symptoms resolved or improved in 10 (91 %) and 25 cases (84 %) in groups II and III, respectively. Syrinx was markedly decreased in 31 cases (86 %) in group III. FMD was less effective for scoliosis (improved or stabilized in 57 %). The persistence of syrinx was related with an aggravation of scoliosis. The outcomes between group IIIa and IIIb showed no significant difference. In most pediatric Chiari I patients with hydrocephalus, a shunting operation was sufficient. FMD showed high efficacy in treating patients without hydrocephalus. The extent of the intradural procedure did not have a significant effect on the clinical outcome.

Moyamoya disease (MMD) is a chronic cerebrovascular occlusive disease, and progressive involvement of the posterior cerebral artery (PCA) has been reported. However, majority of MMD articles are presenting classic anterior circulation related issues. This study investigates the preoperative factors related to the long-term outcome of posterior circulation in MMD. Retrospective review of 88 MMD patients (166 PCAs in either hemisphere) without symptomatic disease involvement of PCA at initial diagnosis was done. Data at initial diagnosis regarding age, presence of infarction, status of the PCA, type of posterior communicating artery, and the angle between PCA and basilar artery were reviewed. Progressive stenosis of PCA was evaluated by symptom or radiological imaging during follow up. During an average follow up of 8.3 years, 29 out of 166 (18 %) evaluated PCAs showed progressive disease involvement. The average time of progression from the initial operation was 4.9 years, with the latest onset at 10.8 years. The patients who showed progressive stenosis of the PCA tended to be younger, present with infarction, have smaller angle between PCA and basilar artery, and have asymptomatic stenosis of the PCA at initial presentation. However, multivariate analysis confirmed only the presence of initial infarction and a smaller angle between PCA and basilar artery to be significantly associated with progressive stenosis of PCA. Involvement of PCA in MMD may occur in a delayed fashion, years after the completion of revascularization of anterior circulation. Persistent long-term follow-up regarding the posterior circulation is recommended.

Cerebellopontine angle (CPA) tumors are uncommon in children, and the pathological spectrum is different from that of adults. In this study, we reviewed the pathological diagnosis of pediatric patients with a CPA tumor to determine the pattern in this age group. In a cohort of 267 patients with posterior fossa tumor, tumor locations were determined with preoperative magnetic resonance imaging (MRI). The pathological diagnosis, imaging characteristic, and treatment outcomes of patients with CPA tumors was reviewed and analyzed. Twenty-six patients (9.7 %) had a tumor in the CPA. The pathological spectrum was wide, from malignant intrinsic brain tumors to benign extra-axial tumors and sarcomatous lesions. Eighteen patients (69 %) had malignant tumors. The pathological nature was strongly linked to patient age. The mean age of malignant tumor group was significantly younger than that of benign tumor group. MRI findings that favored malignant histology included a plastic feature of the tumor, multiple signal voids, encasement of major arteries, widening of lateral recess, focal cerebellar edema, and hydrocephalus. The presence of seeding in the neuraxis also indicated malignant pathology. Especially, increased density on precontrast computed tomography was a strong predictor of malignant pathology. Malignant CPA tumors showed high surgical morbidity rate and grim long-term prognosis. Patient age and tumor location are the two most important clues for the diagnosis of any brain tumor. Unlike in adult patients, clinicians should expect a high probability of malignant histology for pediatric CPA tumors, especially in infants and young children.

Synovial diseases in children can be classified into normal structures as potential sources of pathology (synovial folds: plicae, infrapatellar fat pad clefts); noninfectious synovial proliferation (juvenile idiopathic arthritis, hemophilic arthropathy, lipoma arborescens, synovial osteochondromatosis, pigmented villonodular synovitis, reactive synovitis), and infectious synovial proliferation, deposition disease, vascular malformations, malignancy (including metastasis) and intra-articular/periarticular cysts and cyst-like structures (ganglia). Familiarity with characteristic MR imaging findings of synovial diseases in children and young adults will enable a more confident diagnosis for earlier intervention and directed therapy. The first part of this paper will cover potential pathology of normal synovial structures as well as noninfectious synovial proliferation.

We report a case of isolated periostitis associated with Takayasu arteritis in a 10-year-old boy presenting with calf pain. Radiographs revealed a localized, thick periosteal reaction with irregular margin in the proximal left fibula. MRI revealed irregular thickening with enhancement of the periosteum in the proximal fibula and heterogeneous enhancement along vascular bundles in the calf. Isolated periostitis is a rare skeletal manifestation of systemic vasculitis that could be misdiagnosed as neoplastic or traumatic periosteal reaction.

Systemic hyalinosis is a rare, multisystem, progressive, autosomal recessive disorder of connective tissue characterized by diffuse hyaline deposition in the skin, bone or viscera. Owing to its rarity and initial manifestations that resemble arthrogryposis congenital multiplexa, correct diagnosis can be elusive and often delayed. We present the computed tomography (CT) and whole-body (WB) magnetic resonance (MR) findings in two unrelated children with systemic hyalinosis who came to medical attention because of multiple joint contractures and limitation of motion in early infancy.

Background To compare the clinical and radiological features of intra-/juxta-articular osteoid osteoma and extra-articular osteoid osteoma in skeletally immature patients, paying special attention to the skeletal complications. Methods Osteoid osteoma in 34 children (22 boys and 12 girls, mean age 10.4 years) was dichotomized according to the location of the nidus as intra-/juxta-articular (11 children) or extra-articular (23 children). The following features were compared: diagnostic delay, typical symptoms, synovitis and limited range of joint motion, response to treatment, typical radiographic findings, and skeletal complications. Results Eight of the 11 children with intra-/juxta-articular osteoid osteoma presented with synovitis in the involved joint, which led to a delayed diagnosis for a median 9.5 months. Pain disappeared in all children with surgical or medical interventions, but at the mean 4.9-year follow-up evaluation, skeletal abnormalities around the joint were noted in 5 children (4 proximal femur and 1 distal humerus) with intra-/juxta-articular osteoid osteoma, 2 of whom required subsequent surgeries for limited hip motion caused by femoroacetabular impingement and limited range of elbow motion, respectively. In contrast, typical clinical and radiological features were observed more often in extra-articular osteoid osteoma, and only 1 child showed overgrowth of the tibia, which did not have clinical significance. Conclusions Intra-/juxta-articular osteoid osteomas in growing children exhibit different clinical and radiological features from extra-articular lesions. Skeletal abnormalities mainly develop in intra-/juxta-articular osteoid osteoma, and these may lead to permanent skeletal sequelae.

Background: Nutcracker syndrome is characterized by gross haematuria caused by left renal vein (LRV) entrapment. Objective: To assess the role of LRV ultrasonography in the diagnosis of the nutcracker syndrome in children. Materials and methods: Twelve children (eight male, four female; mean age 12.8 years) with venographically confirmed nutcracker syndrome (LRV-IVC pressure gradient ≥3 mm Hg) underwent LRV sonography including Doppler spectral analysis (n=7). The diameter and peak velocity (PV) were measured at two sites of the LRV (renal hilum and aortomesenteric portion). The US findings of nutcracker syndrome were compared with those of 20 control subjects using the t-test. We identified the optimal cut-off value of the US parameters for the diagnosis of the nutcracker syndrome using ROC analysis. Results: The PV at the aortomesenteric portion and the ratio of the PV between the two measured points showed significant differences between the two groups (P

Background: The diagnosis of squalene aspiration pneumonia in children is often difficult because of minimal non-specific symptoms. Objective: To investigate the radiological findings of squalene aspiration pneumonia in children. Materials and methods: We reviewed the chest radiographs (n = 8) and CT scans (n = 7), including high-resolution CT (n = 3), of eight patients (four boys, four girls; age 3 months to 6 years) with squalene aspiration pneumonia. All patients presented minimal symptoms. Results: Chest radiographs showed right-sided predominantly parahilar infiltrations. The extent and the opacity of the lesions decreased slowly during the follow-up period (mean 5.4 months) after halting the exposure. On CT, affected areas appeared as dense consolidations surrounded by ground-glass opacities showing a crazy-paving pattern in a geographic lobular distribution in all patients. The lesions were predominantly in the right lung and dependent areas in all patients and extensively involved all pulmonary lobes in five patients. Conclusions: These radiological findings, although non-specific, can lead to an appropriate diagnosis, particularly when patients present few symptoms.

Inflammatory myofibroblastic tumour of the liver is a rare disease in children and is characterized by an inflammatory mass of uncertain aetiology which simulates a true neoplasm, often resulting in a diagnostic dilemma. We report a pathologically proven case of inflammatory myofibroblastic tumour of the liver in a 14-month-old boy with jaundice. CT and MRI showed an ill-defined, homogeneously enhancing mass located in the hilar portion of the liver with biliary obstruction. He underwent percutaneous transhepatic biliary drainage to relieve obstructive jaundice, followed by lobectomy and, finally, liver transplantation.

Gastric adenomyoma is a rare tumour-like lesion composed of glandular components and smooth muscle bundles. We report a case of gastric adenomyoma in a 1-week-old neonate who presented with gastric outlet obstruction. To the best of our knowledge, this is the youngest child reported with gastric adenomyoma and a unique case demonstrating radiological findings of gastric adenomyoma in a young infant. At US, the lesion was seen as an asymmetrical mass-like wall-thickening of the pylorus. Upper gastrointestinal series showed findings similar to those seen in a case of hypertrophic pyloric stenosis. We suggest that gastric adenomyoma should be included in the causes of gastric outlet obstruction in neonates even though it is rare in young children.

We present a case of intramedullary spinal gangliocytoma in a 7-year-old girl who presented with scoliosis and progressive weakness of both legs. The tumour involved the whole spinal cord and medulla oblongata and was composed of inner cystic and outer solid components. On MRI, the solid portion of the lesion showed strong enhancement at the thoracolumbar level and mild enhancement at the cervical and medullary levels. Histological examination of the surgical specimen showed neoplastic ganglion cells arranged irregularly in benign normocellular glial background, which made a diagnosis of gangliocytoma.

Posterior circulation infarction is uncommon in children. We describe the clinical presentation and radiological findings in two children with cerebellar infarction resulting from dissection of the vertebral artery. We emphasize that vertebral artery injury should be considered in a child with acute symptoms and signs of ischaemia in the posterior circulation. MRI and MRA may be helpful in the diagnosis of cerebellar infarction and vertebral artery abnormality.

We present two cases of granulocytic sarcoma of the cervical lymph nodes with central necrosis as an initial manifestation of childhood leukaemia, focusing on the imaging features. Recognition of the CT and MR imaging findings of granulocytic sarcoma involving the cervical lymph nodes assists the differential diagnosis of noninfective lymphadenopathy in children.

Background. Focal nodular hyperplasia (FNH) is an unusual hepatic tumour in children and should be distinguished from other hepatic lesions. Objective. To describe the imaging characteristics of FNH in children. Materials and methods. We examined five patients (three boys and two girls, mean age 9.4 years) with pathologically confirmed FNH. The diagnosis was obtained by tumour resection (n = 4) and percutaneous needle biopsy (n = 1). One patient with multiple FNHs showed recurrent lesions after tumour resection. All patients were studied with US (including colour and power Doppler US [n = 3]) and CT. Dynamic enhanced CT scans were available in three patients. MRI (n = 2) or coeliac angiography (n = 1) was performed in three patients. Results. Seven of eight FNH lesions in five patients were demonstrated by imaging. The average size of the lesions was 6.5 cm. Six lesions detected on US showed variable echogenicity with a central hyperechoic scar (n = 2). On Doppler examination, central or peripheral hypervascular areas were seen (n = 3). Six lesions detected on contrast-enhanced CT showed high attenuation (n = 4) or iso-attenuation (n = 2). On early phase scans, all the lesions (n = 3) showed high attenuation. Irregular linear or ovoid central scars were detected in two patients on CT. MR demonstrated three lesions in two patients, one of which had not been detected by US or CT. A central low signal intensity scar (n = 1) was seen on T2-weighted MRI. Coeliac angiography performed in one patient showed a hypervascular mass with homogeneous staining. Conclusion. FNH in children shows a wide spectrum of imaging findings on various radiological examinations and the typical central scar was not always seen on imaging studies. Dynamic enhanced CT obtained in the early phase and colour Doppler studies may be helpful in the diagnosis of FNH by allowing characterisation of tumour vascularity. FNH should be included in the differential diagnosis of liver mass in children.

Congenital abnormalities of the portal venous system are rare. There are few radiological descriptions of intrahepatic portosystemic venous shunt detected in the perinatal period. We report a congenital portosystemic shunt that was detected by US and treated with coil embolisation in the neonatal period.

With the increasing application of intra-arterial chemotherapy (IAC), new side-effects are encountered. We describe two children with proximal femoral osteosarcoma who developed focal myositis of the abdominal wall musculature after IAC. In both cases, myositis presented as abdominal pain and mimicked acute abdomen. US demonstrated asymmetrical thickening of abdominal-wall musculature in the right lower abdomen. This diagnosis should be considered when evaluating the patient with unexplained abdominal pain and a history of IAC.

)Department of Pediatrics, Seoul National University Collegeof Medicine, 28 Yongondong, Jongrogu, Seoul 110-744, Koreae-mail: jkseo@snu.ac.krJ. S. Koe-mail: kojs@snu.ac.krJ. M. Yoone-mail: ruleout@empal.comH. R. Yange-mail: hrlamb@hanmail.netJ. K. Myung H. Kim G. H. KangDepartment of Pathology, Seoul National University Collegeof Medicine, 28 Yongondong, Jongrogu, Seoul, KoreaH. Kime-mail: medannabel@gmail.comG. H. Kange-mail: ghkang@snu.ac.krJ.-E. CheonDepartment of Radiology, Seoul National University Collegeof Medicine, 28 Yongondong, Jongrogu, Seoul, Koreae-mail: cheonje@snu.ac.kr