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Objective To evaluate the diagnostic performance of a deep learning algorithm for the automated detection of developmental dysplasia of the hip (DDH) on anteroposterior (AP) radiographs. Materials and Methods Of 2601 hip AP radiographs, 5076 cropped unilateral hip joint images were used to construct a dataset that was further divided into training (80%), validation (10%), or test sets (10%). Three radiologists were asked to label the hip images as normal or DDH. To investigate the diagnostic performance of the deep learning algorithm, we calculated the receiver operating characteristics (ROC), precision-recall curve (PRC) plots, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) and compared them with the performance of radiologists with different levels of experience. Results The area under the ROC plot generated by the deep learning algorithm and radiologists was 0.988 and 0.988–0.919, respectively. The area under the PRC plot generated by the deep learning algorithm and radiologists was 0.973 and 0.618–0.958, respectively. The sensitivity, specificity, PPV, and NPV of the proposed deep learning algorithm were 98.0, 98.1, 84.5, and 99.8%, respectively. There was no significant difference in the diagnosis of DDH by the algorithm and the radiologist with experience in pediatric radiology (p = 0.180). However, the proposed model showed higher sensitivity, specificity, and PPV, compared to the radiologist without experience in pediatric radiology (p < 0.001). Conclusion The proposed deep learning algorithm provided an accurate diagnosis of DDH on hip radiographs, which was comparable to the diagnosis by an experienced radiologist.

Purpose: Swyer-James-Macleod syndrome (SJMS) is a rare disorder characterized by the hyperlucency of a unilateral lung due to ip silaterally arrested lung growth. No sufficient information on progressive lung function changes during growth is available in SJMS. Methods: We retrospectively reviewed SJMS cases using a clinical database from January 2000 to August 2018. Results: A total of 40 patients were enrolled in this study. The median age of the patients was 4.8 years (interquartile range [IQR], 2.7-9.0 years), boys (n=21, 52.5%) were more affected, and left lungs (n=27, 67.5%) were more involved. The interval between in fection and diagnosis was 1.8 years (IQR, 0.7-6.4 years). Mycoplasma pneumoniae (n=14) and adenovirus (n=5) were most preva lent among the 21 subjects with presumably identifiable causes. Most of the 16 patients with available pulmonary function data presented moderate obstructive lung function (z-score, median; FEV1: -4.320 [IQR, -5.955 to -3.400] and FVC: -2.600 [IQR, -3.590 to -1.570], respectively) with the more decreased median in forced expiratory flow between 25% and 75% of FVC (FEF25%-75%) (z-score, -4.470; IQR, -5.330 to -3.170). Linear mixed effect models indicated that younger age at first infectious insult was significantly related to decreased FEV1 z-score (P=0.041), and that the FEV1/FVC and FEF25%-75% z-scores were reduced by 0.082 (P=0.005) and 0.069 (P≤0.001) per year. Conclusion: In children with SJMS, the initial infectious insult occurs in the early life with M. pneumoniae being the most common pathogen. Lung function may deteriorate with an obstructive pattern during growth. The impairment can progress slowly not in the FEV1, but in the FEV1/FVC or FEF25%-75%. (Allergy Asthma Respir Dis 2021;9:156-163)

OBJECTIVE: To assess the role of arterial spin-labeling (ASL) perfusion MRI in identifying cerebral perfusion changes after indirect revascularization in children with moyamoya disease. MATERIALS AND METHODS: We included pre- and postoperative perfusion MRI data of 30 children with moyamoya disease (13 boys and 17 girls; mean age ± standard deviation, 6.3 ± 3.0 years) who underwent indirect revascularization between June 2016 and August 2017. Relative cerebral blood flow (rCBF) and qualitative perfusion scores for arterial transit time (ATT) effects were evaluated in the middle cerebral artery (MCA) territory on ASL perfusion MRI. The rCBF and relative time-to-peak (rTTP) values were also measured using dynamic susceptibility contrast (DSC) perfusion MRI. Each perfusion change on ASL and DSC perfusion MRI was analyzed using the paired t test. We analyzed the correlation between perfusion changes on ASL and DSC images using Spearman's correlation coefficient. RESULTS: The ASL rCBF values improved at both the ganglionic and supraganglionic levels of the MCA territory after surgery (p = 0.040 and p = 0.003, respectively). The ATT perfusion scores also improved at both levels (p < 0.001 and p < 0.001, respectively). The rCBF and rTTP values on DSC MRI showed significant improvement at both levels of the MCA territory of the operated side (all p < 0.05). There was no significant correlation between the improvements in rCBF values on the two perfusion images (r = 0.195, p = 0.303); however, there was a correlation between the change in perfusion scores on ASL and rTTP on DSC MRI (r = 0.701, p < 0.001). CONCLUSION: Recognizing the effects of ATT on ASL perfusion MRI may help monitor cerebral perfusion changes and complement quantitative rCBF assessment using ASL perfusion MRI in patients with moyamoya disease after indirect revascularization.

Background Previous classification systems of pectus excavatum have been based on subjective morphologic characteristics. We sought to suggest a new classification system derived from objective variables. Methods Patients who underwent surgical repair of pectus excavatum without a history of previous chest operations were included. Objective morphologic variables were measured from chest computed tomography scan images, and classification was performed by hierarchical clustering of measured indexes. Clinical relevance of the suggested classification was also verified. Results Included were 230 patients who underwent operation for pectus excavatum from January 2001 to August 2013. These patients were classified into two major groups: typical (group I; 197 [85.7%]) and atypical (group II; 33 [14.3%]). Group I was further classified into three subgroups according to flatness and symmetry of the chest wall. Group II was further classified into four subgroups according to the severity of sternal torsion and sternal angulation. Two unique types of deformity were identified in group II: the double distortion subgroup (group IIa; 8 [3.5%]) and the reverse torsion subgroup (group IIc; 16 [7.0%]). Scoliosis was more frequently associated with group IIa ( p = 0.008). Conclusions Morphologic classification obtained from computed tomography indexes hierarchical clustering identified seven distinct subtypes of pectus excavatum.

Purpose To assess the usefulness of the relative position of the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) in diagnosing intestinal malrotation in situs anomaly. Materials and methods From January 2004 to April 2015, 33 patients with situs anomalies were enrolled in this study who underwent abdominal USG, CT or MRI as well as upper gastrointestinal series (UGIS) or surgery: situs inversus (n = 16), left isomerism (n = 10), and right isomerism (n = 7); age 21.2 ± 23.2 years (mean ± standard deviation), range 0–72 years. The intestinal malrotation was confirmed with UGIS and/or operation in 16 patients. Relative positions of the SMV to the SMA were classified into four groups by reviewing abdominal USG, CT, or MRI: right sided, left sided, ventral sided, and dorsal sided. The incidence of malrotation was analyzed for each group. Results In 16 patients with situs inversus, there was reversed SMA-SMV relationship: left sided (n = 11) or ventral sided (n = 5). One situs inversus patient with ventral sided SMV had intestinal malrotation (6.25%). 17 patients with situs ambiguus showed various SMA-SMV relationships (ventral sided, n = 7; left sided, n = 5; right sided, n = 4; dorsal sided, n = 1). Among them, 15 patients (88.2%) had intestinal malrotation. Two patients with normal rotation had either right sided or dorsal sided SMV. Conclusion Situs ambiguus was commonly associated with intestinal malrotation with a variable SMA-SMV relationship. Reversal of the mesenteric vascular relationship was observed in situs inversus with normal rotation, not excluding the possibility of intestinal malrotation.

To evaluate the changes in using patterns of brain magnetic resonance imaging (MRI) in preterm infants after introduction of a MR-compatible incubator coil system.Brain MRIs for preterm infants with the MR-compatible incubator coil from March 2010 to July 2014 (n=154, group A) were compared with MRIs prior to the introduction of the incubator coil, from March 2005 to February 2010 (n=65, group B). Clinical data, MRI findings, acquisition time, and incidence of adverse events during the study were retrospectively reviewed. For the qualitative analysis of the examinations, the presence of motion artefact, spatial resolution, and overall image quality were assessed. Signal uniformity of each sequence was evaluated for a quantitative comparison.Comparing with group B, Group A was significantly younger (36+3 vs. 38+3 weeks, p0.001), had a significantly lower body weight (2006.6 and 2390.3g respectively; p0.001) at the time of MRI, and had shorter time interval (54.3±2.6 vs. 70.5±4.4days, p=0.002) between birth and examination. Abnormal findings were noted more frequently in group A (n=100, 65%) than in B (n=24, 37%. p=0.001) with a significantly higher incidence of diffusion restriction (n=21, 13.6% vs. n=4, 6.2%, p=0.034). Mean image acquisition time was significantly shorter in group A (21.4±4.5 vs. 25.4±5.5min, p0.001) with significant lower adverse events during MRI (n=26, 40 vs. n=6, 3.9%, p0.001). Group A exhibited significantly less motion artefact, better spatial resolution, and better overall image quality with decreased signal variation than group B (all p0.001).Application of the MR-compatible incubator for preterm brain MRI evaluation is safer and provides more timely evaluation of preterm infants with better image quality.

To evaluate the ultrasonography (US) features of Alagille syndrome (ALGS), as compared with biliary atresia (BA) or neonatal hepatitis (NH).Our study included 23 ALGS, 75 BA and 70 NH patients. The initial US images were retrospectively reviewed for gallbladder (GB) morphology with systemic classification, GB length and luminal area, presence of triangular-cord (TC) sign and hypertrophied hepatic-artery. The presence of anomalies associated with ALGS was evaluated. The diagnostic values of each finding and their combinations were evaluated.Both ALGS (57%) and BA (79%) were more frequently associated with abnormal GB shapes than NH (19%, all P0.001). The short and small GBs were more frequently observed in ALGS and BA than in NH (all P0.001). None in the ALGS and NH showed TC sign, while 41% in the BA did (all P0.001). Hypertrophied hepatic-artery was noted less frequently in both ALGS (13%) and NH (14%) than in BA (83%, all P0.001). The combination of US criteria with associated anomalies increased the positive-predictive-value for ALGS.Abnormal shaped GB with absence of the TC sign and hypertrophied hepatic-artery and presence of associated anomalies can be a differential point of ALGS.

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 (

Objective To evaluate the incidence and risk factors of emetic complications associated with the intravenous administration of low-osmolality iodinated contrast media (ICM) in children undergoing computed tomography (CT). Materials and methods All children who underwent contrast-enhanced CT between April 2017 and July 2019 were included. Pediatric patients were instructed on the preparative dietary protocol at our institution. Experienced nurses in the radiology department monitored the children during the CT scans and recorded any emetic complications in their electronic medical records. These data were used to calculate the incidence of emetic complications. Various patient factors and technical factors, including fasting duration, the type and volume of ICM, and ongoing chemotherapy, were evaluated to identify risk factors for emetic complications using univariate and multivariate logistic regression analyses. Results Among the 864 children (mean age, 8.4 ± 5.7 years) evaluated, 18 (2.1%) experienced emetic complications (6 experienced nausea only and 12 experienced nausea and vomiting). None of the children developed aspiration pneumonia. The mean fasting duration of patients with emesis was 7.9 ± 5.7 hours (range, 3-21 hours), whereas that of patients without nausea was 8.7 ± 5.7 hours (range, 0-24 hours). Fasting duration was not associated with the development of nausea and vomiting (p = 0.634). Multivariate logistic regression analysis revealed that ongoing chemotherapy (odds ratio [OR] = 4.323; 95% confidence interval [CI] = 1.430-13.064; p = 0.009), iomeprol use (OR = 7.219; 95% CI = 1.442-36.146; p = 0.016), and iohexol use (OR = 5.241; 95% CI = 1.350-20.346; p = 0.017) were independent risk factors for emetic complications. Conclusion Only a small proportion (2.1%) of children experienced nausea or vomiting after exposure to low-osmolality ICM. Many children underwent excessive fasting; however, fasting duration was not associated with nausea and vomiting. Moreover, ongoing chemotherapy and the use of iomeprol or iohexol were identified as potential risk factors for emetic complications in children.

Purpose: Pulmonary underdevelopment is one of the pulmonary causes of neonatal mortality, which is categorized into pulmonary agenesis, pulmonary aplasia, and pulmonary hypoplasia. Congenital diaphragmatic hernia is a well-known cause of pulmonary hy poplasia; however, further studies are needed for other etiologies. Patients with pulmonary underdevelopment show varying de grees of clinical severity. Most patients with pulmonary underdevelopment have respiratory distress at birth, while a few have only mild symptoms. Our study investigated the natural course and prognosis of pulmonary underdevelopment by analyzing multiple cases from a single tertiary medical center. Methods: A retrospective review was conducted on patients diagnosed with pulmonary hypoplasia and agenesis from January 2000 to August 2019. Cases were extracted from the clinical database of Seoul National University Children’s Hospital by searching for keywords related to pulmonary underdevelopment. Results: A total of 28 patients were identified. Four patients had pulmonary agenesis, and all were idiopathic. Twenty-four patients had evidence of pulmonary hypoplasia with diverse causes. The median age at diagnosis was 11.5 days (range, 1-240 days) and the mean gestational age was 35 weeks 2 days±3 weeks 6 days. Twenty patients received ventilator care and 11 had various degrees of pulmonary hypertension. The long-term survival rate was 50%. The median age of death among pulmonary hypoplasia patients were 11 days (range, 1-730 days). All patients without ventilator care survived. The incidence of ventilator care, pneumothorax, and pulmonary hypertension were significantly higher among patients who died. Conclusion: The prognosis of pulmonary underdevelopment depends on the severity of respiratory distress and pulmonary hyper tension in earlier life. Patients with severe distress appear to have severe degree of pulmonary hypoplasia. Patients without ventila tor support in the neonatal period survived without significant morbidities. (Allergy Asthma Respir Dis 2020;8:206-212)

The purpose of this study was to evaluate the usefulness of radially sampled 3D fat-suppressed T1-weighted gradient-echo sequences (radial volumetric interpolated breath-hold examination [radial VIBE]) for contrast-enhanced brain MRI of children through comparison with a magnetization-prepared rapid-acquisition gradient-echo (MP-RAGE) sequence.Sixty-five consecutive contrast-enhanced brain MRI examinations performed with axial MP-RAGE and radial VIBE sequences were included. For quantitative analysis, coefficients of variation of gray matter and white matter and CSF and relative contrast between tissue types (gray matter and white matter, gray matter and CSF, and white matter and CSF) for each sequence were calculated. For qualitative assessment, motion, pulsation artifacts, overall image quality, and lesion conspicuity were retrospectively scored on a 5-point scale. Quantitative and qualitative subgroup analyses were performed for patients with serious motion artifacts.Images obtained with the radial VIBE sequence had fewer motion and pulsation artifacts than those obtained with the MP-RAGE sequence (MP-RAGE vs radial VIBE motion score, 3.57 ± 1.00 vs 4.52 ± 0.51; pulsation score, 3.57 ± 0.60 vs 4.91 ± 0.21; all p0.001). Among 25 images with serious motion artifacts, radial VIBE images had significantly higher scores for all qualitative parameters, including overall image quality, than did MP-RAGE images (overall image quality for MP-RAGE vs radial VIBE, 2.63 ± 0.82 vs 3.42 ± 0.55, p0.001).The study showed that a radial fat-suppressed T1-weighted gradient-echo sequence is a viable alternative to conventional cartesian acquisition for contrast-enhanced brain imaging of restless children.

Mutations of the surfactant protein (SP)-C gene (SFTPC) have been associated with neonatal respiratory distress syndrome (RDS) and childhood interstitial lung disease (ILD). If accurate diagnosis and proper management are delayed, irreversible respiratory failure demanding lung transplantation may ensue. A girl was born at term but was intubated and given exogenous surfactant due to RDS. Cough and tachypnea persisted, and symptoms rapidly progressed at 16 months of age despite treatment with antibiotics, oral prednisolone, methylprednisolone pulse therapy, and intravenous immunoglobulin. At 20 months, she visited our hospital for a second opinion. A computed tomography scan showed a diffuse mosaic pattern with ground-glass opacity and subpleural cysts compatible with ILD. A video-assisted thoracoscopic lung biopsy revealed ILD with eosinophilic proteinaceous material and macrophages in the alveolar space. Bilateral lung transplant from a 30-month-old child was done, and she was discharged in room air without acute complications. Genetic analysis revealed a novel c.203T>A, p.Val68Asp mutation of SP-C, based on the same exon as a known pathogenic mutation, p.Glu66Lys.

BACKGROUND AND PURPOSE: For the postoperative follow-up in pediatric patients with Moyamoya disease, it is essential to evaluate the degree of neovascularization status. Our aim was to quantitatively assess the neovascularization status after bypass surgery in pediatric Moyamoya disease by using color-coded digital subtraction angiography. MATERIALS AND METHODS: Time-attenuation intensity curves were generated at ROIs corresponding to surgical flap sites from color-coded DSA images of the common carotid artery, internal carotid artery, and external carotid artery angiograms obtained pre- and postoperatively in 32 children with Moyamoya disease. Time-to-peak and area under the curve values were obtained. Postoperative changes in adjusted time-to-peak (ΔTTP) and ratios of adjusted area under the curve changes (ΔAUC ratio) of common carotid artery, ICA, and external carotid artery angiograms were compared across clinical and angiographic outcome groups. To analyze diagnostic performance, we categorized clinical outcomes into favorable and unfavorable groups. RESULTS: The ΔTTP at the common carotid artery increased among clinical and angiographic outcomes, in that order, with significant differences ( P = .003 and .005, respectively). The ΔAUC ratio at the common carotid artery and external carotid artery also increased, in that order, among clinical and angiographic outcomes with a significant difference (all, P = .000). The ΔAUC ratio of ICA showed no significant difference among clinical and angiographic outcomes ( P = .418 and .424, respectively). The ΔTTP for the common carotid artery of >1.27 seconds and the ΔAUC ratio of >33.5% for the common carotid artery and 504% for the external carotid artery are revealed as optimal cutoff values between favorable and unfavorable groups. CONCLUSIONS: Postoperative changes in quantitative values obtained with color-coded DSA software showed a significant correlation with outcome scores and can be used as objective parameters for predicting the outcome in pediatric Moyamoya disease, with an additional cutoff value calculated through the receiver operating characteristic curve.

The purpose of this study was to compare wide-volume and helical pediatric 320-MDCT of the chest with respect to radiation dose and image quality.From November 2012 to September 2013, 59 wide-volume and 47 helical pediatric chest 320-MDCT images were obtained. The same tube potential and effective tube current-time product were applied in the two groups according to patient weight (group A,10 kg, n = 18; group B, 10-19.9 kg, n = 60; group C, 20-39.9 kg, n = 28). To compensate for overranging, adjusted CT dose index (CTDI) was calculated by dividing dose-length product (DLP) by the scan ranges imaged. Adjusted CTDI, DLP, overall image quality, motion artifact, noise, and scan ranges were compared by Mann-Whitney U test or t test.The adjusted CTDI was significantly lower in the group who underwent wide-volume CT than in the group who underwent helical CT (weight group A, p0.001; group B, p0.001; group C, p = 0.003). The DLP was lower in the wide-volume group than in the helical CT group in weight groups A (p0.001) and B (p0.001) but not in group C (p = 0.162). All CT scans were of diagnostic quality, and there was no significant difference between the wide-volume and helical CT groups (p = 0.318). The motion artifact score was significantly higher in the wide-volume group than in the helical CT group in groups B (p0.001) and C (p = 0.010) but not in group A (p = 0.931). The noise was significantly lower in the wide-volume group than in the helical CT group (p0.001).In pediatric chest CT, use of wide-volume CT can decrease radiation exposure while preserving image quality. It is associated with less noise than helical CT but may be subject to more motion artifact.

This study aimed to assess the therapeutic results of ultrasound (US)-guided water-soluble contrast enema in very low birth weight (VLBW) preterm infants (1,500 g) with meconium obstruction and to study factors that affect therapeutic results.This study included a total of 33 consecutive VLBW infants with clinically diagnosed meconium obstruction underwent US-guided water-soluble contrast enema, from April 2007 to March 2014. Patients were classified into two groups based on to procedure outcome: the success group (evacuation of the meconium plug resolution followed by improved bowel distention within 2 days of the procedure, without additional interventions), and the failure group (the contrast enema failed to relieve the obstruction, or other procedure-related complications occurred). Patient- and mother-related clinical factors and procedure-related factors were compared between both groups.Overall success rate was 54.5%, with 18 successful (M:F=10:8), and 15 failure (M:F=7:8) cases. When compared with the failure group, the success group patients showed statistically significant older gestational age (29(+1) vs. 27 weeks; p=0.028), larger birth weight (1023.1g vs. 790.3g; p=0.048), and higher body weight on the day of the procedure (1036.2g vs. 801.6g, p=0.049). However, no statistically significant differences were seen between other patient and maternal factors. Among the procedure-related factors, retrial of contrast injection during the procedure was associated with significantly higher success than the single trial (p=0.027). The presence of refluxed contrast into the distal ileum was the statistically significant predictor for success of the procedure (p=0.038). There were three cases of bowel perforation (9.1% per person).US-guided water-soluble contrast enema in VLBW infants with meconium obstruction showed a 54.5% success rate and a 9.1% perforation rate per person. Among the procedure-related factors, retrial of contrast injection during the procedure and the presence of refluxed contrast into the distal ileum were related to the success of the procedure.

Objectives To analyze the texture features on cranial sonography in preterm neonates with white matter injury quantitatively and to correlate these features with magnetic resonance imaging (MRI). Methods The study included 33 preterm neonates treated in our neonatal intensive care unit who underwent serial cranial sonography and brain MRI near term. Patients were subdivided into 3 groups according to the presence and severity of white matter injury as revealed by MRI: normal (group 1; n = 20), mild (group 2; n = 5), and severe (group 3; n = 8). The periventricular echogenicity on sonography was evaluated quantitatively with second-order gray-level statistics (gray-level co-occurrence matrix [GLCM] method). Four GLCM texture features representing homogeneity were extracted in 12 directions: (1) angular second moment (ASM), (2) inverse differential moment (IDM), (3) contrast, and (4) entropy. Results Thirty of 48 features showed a statistically significant difference between groups 1 and 3 (ASM in 9 directions, IDM in 6 directions, contrast in 3 directions, and entropy in all 12 directions). There were no significant differences observed between groups 1 and 2 or groups 2 and 3. The mean contrast and entropy values were generally lower in group 1 than group 3, whereas the mean ASM and IDM values were higher in group 1. Conclusions Severe white matter injury could be identified by using GLCM texture analysis, whereas mild white matter injury observed on MRI could not be evaluated by GLCM analysis. Quantitative texture analysis using the GLCM may serve as a complementary tool for quantitative assessment of periventricular echogenicity.

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

Mutations of the surfactant protein (SP)-C gene (SFTPC) have been associated with neonatal respiratory distress syndrome (RDS) and childhood interstitial lung disease (ILD). If accurate diagnosis and proper management are delayed, irreversible respiratory failure demanding lung transplantation may ensue. A girl was born at term but was intubated and given exogenous surfactant due to RDS. Cough and tachypnea persisted, and symptoms rapidly progressed at 16 months of age despite treatment with antibiotics, oral prednisolone, methylprednisolone pulse therapy, and intravenous immunoglobulin. At 20 months, she visited our hospital for a second opinion. A computed tomography scan showed a diffuse mosaic pattern with ground-glass opacity and subpleural cysts compatible with ILD. A video-assisted thoracoscopic lung biopsy revealed ILD with eosinophilic proteinaceous material and macrophages in the alveolar space. Bilateral lung transplant from a 30-month-old child was done, and she was discharged in room air without acute complications. Genetic analysis revealed a novel c.203T>A, p.Val68Asp mutation of SP-C, based on the same exon as a known pathogenic mutation, p.Glu66Lys., Graphical Abstract

BACKGROUND In free flap reconstruction for head and neck cancer, achieving a haemodynamic target using excessive fluid infusion is associated with decreased flap survival rates and extended hospital stays. We hypothesized that goal-directed haemodynamic therapy would improve flap survival rates and shorten hospitalization periods. METHODS Patients scheduled for free flap reconstruction were randomly assigned to a goal-directed haemodynamic therapy group (n = 31) or a conventional haemodynamic therapy control group (n = 31). The control group received extra bolus fluid and ephedrine or norepinephrine to maintain a mean arterial pressure ≥ 65 mmHg. The goal-directed haemodynamic therapy group received a colloid solution as the extra bolus fluid to maintain a stroke volume variation < 12%; dobutamine, ephedrine, or norepinephrine was administered to maintain a cardiac index ≥ 2.5 l/min/m2 and mean arterial pressure ≥ 65 mmHg. Enhanced recovery after surgery protocols were not used except for fluid therapy. An otolaryngologist blinded to group assignments assessed flap outcomes and classified them as 'survival,' 'at risk' or 'failure.' RESULTS The hospitalization period was not significantly different between the groups. The goal-directed haemodynamic therapy group had significantly shorter intensive care unit stays and a higher flap survival rate. The crystalloid volume was significantly lower in goal-directed haemodynamic therapy group. Reoperation rates, post-operative complications, and laboratory data including inflammatory markers were similar between the groups. CONCLUSION Compared to conventional haemodynamic therapy, goal-directed haemodynamic therapy does not reduce hospitalization periods; it may, however, reduce the length of intensive care unit stays and increase flap survival rates. Further studies including multi-centre trials with larger sample sizes are warranted.

Purpose To evaluate the patients’ morphologic factors affecting radiation dose in pediatric chest CT. Materials and methods From November 2013 to May 2015, 315 pediatric chest CT scans were obtained using a CT scanner, and classified into 5 groups according to the patients’ age. For each age group, the chest CT scans were divided into two subgroups. A cut-off value used was the 75th percentile of size-specific dose estimates (SSDE), age-specific diagnostic reference level (DRL): less than the 75th percentile of SSDE (Group A, n = 238) and greater than the 75th percentile of SSDE (Group B, n = 77). All CT scans were performed with the same protocol using automatic tube voltage selection and current modulation techniques. The morphologic factors of the patients including body mass index (BMI), arm angles, presence of medical devices in the scan field, and degree of off-centering within the CT gantry were compared between groups A and B. Results Group B showed narrower arm angles on scout and coronal reformatted images, higher frequency of the presence of devices and higher BMI than group A (P < 0.001, P < 0.001; P = 0.018, and P < 0.001, respectively). In multivariate analysis, narrower arm angles, the presence of devices on the scout images and higher BMI were independently associated with higher SSDE (P = 0.001, P = 0.037, and P < 0.001, respectively). Conclusions During acquisition of the scout images, arms-down position and the presence of medical devices were associated with a high radiation dose above age-specific DRLs in pediatric chest CT, regardless of repositioning before the actual scanning. In addition, off-centering had no clinical impact on radiation dose in the routine practice.

The 320-row multidetector computed tomography (CT) scanner has multiple scan modes, including volumetric modes. To compare the image quality and radiation dose of 320-row CT in three acquisition modes — helical, one-shot volume, and wide-volume scan — at pediatric brain imaging. Fifty-seven children underwent unenhanced brain CT using one of three scan modes (helical scan, n=21; one-shot volume scan, n=17; wide-volume scan, n=19). For qualitative analysis, two reviewers evaluated overall image quality and image noise using a 5-point grading system. For quantitative analysis, signal-to-noise ratio, image noise and posterior fossa artifact index were calculated. To measure the radiation dose, adjusted CT dose index per unit volume (CTDIadj) and dose length product (DLP) were compared. Qualitatively, the wide-volume scan showed significantly less image noise than the helical scan (P=0.009), and less streak artifact than the one-shot volume scan (P=0.001). The helical mode showed significantly lower signal-to-noise ratio, with a higher image noise level compared with the one-shot volume and wide-volume modes (all P

Background Neurofibromatosis type 1 (NF1) is an autosomal dominant disease with prominent neurocutaneous manifestations. The most common intracranial imaging finding of NF1 on brain magnetic resonance imaging (MRI) is the high-signal intensity foci without a mass effect or growth in size. Patient Description We describe two children with NF1 in whom brain MRI showed growing cystic lesions and adjacent white matter signal abnormalities, which were confirmed as non-neoplastic cystic degeneration and reactive gliosis. Conclusion Growing cyst-like white matter lesions can be seen on serial brain MRI in children with NF1. Reactive gliosis with cystic degeneration could be a pathogenic basis of these cystic lesions.

Background With the emergence of macrolide resistance, concerns about the efficacy of macrolides for the treatment of Mycoplasma pneumoniae (MP) pneumonia in children have been raised. This study aimed to determine the effect of macrolide resistance on the outcome of children who were hospitalized with MP pneumonia. Methods Between 2010 and 2015, we performed culture of MP from nasopharyngeal samples obtained from children who were hospitalized with pneumonia at five hospitals in Korea. Macrolide resistance was determined by the analysis of 23S rRNA gene transition and the minimal inhibitory concentrations of four macrolides. Medical records were reviewed to analyze the clinical response to treatment with macrolides. Results MP was detected in 116 (4.8%) of the 2436 children with pneumonia. MP pneumonia was prevalent in 2011 and 2015. Of the 116 patients with MP pneumonia, 82 (70.7%) were macrolide-resistant. There were no differences in the age distribution, total duration of fever, and chest x-ray patterns between the macrolide-susceptible and macrolide-resistant groups. After macrolide initiation, mean days to defervescence were longer in the macrolide-resistant group than in macrolide-susceptible group (5.7 days vs. 4.1 days, P = 0.021). However, logistic regression analysis revealed that the presence of extrapulmonary signs (P = 0.039), homogeneous lobar consolidation (P = 0.004), or parapneumonic effusion (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.

BackgroundRadiologic evaluation of children with Mycoplasma pneumoniae is important for diagnosis and management.ObjectiveTo investigate the correlation between chest radiographic findings and the clinical features in children with Mycoplasma pneumoniae pneumonia.Materials and methodsThis study included 393 hospitalized children diagnosed with M. pneumoniae pneumonia between January 2000 and August 2016. Their clinical features and chest radiographs were reviewed. Radiographic findings were categorized and grouped as consolidation group (lobar or segmental consolidation) and non-consolidation group (patchy infiltration, localized reticulonodular infiltration, or parahilar peribronchial infiltration).ResultsLobar or segmental consolidation (37%) was the most common finding, followed by parahilar or peribronchial infiltration (27%), localized reticulonodular infiltration (21%) and patchy infiltration (15%). The consolidation group was more frequently accompanied by pleural effusions (63%), compared to the non-consolidation group (16%). Compared with patients in the non-consolidation group, those in the consolidation group were associated with a significantly higher rate of hypoxia, tachypnea, tachycardia, extrapulmonary manifestations, prolonged fever, and longer periods of anti-mycoplasma therapy and hospitalization. Lobar or segmental consolidation was significantly more frequent in children ≥5 years old (44%) compared with children 2-5 years old (34%) and ConclusionThe chest radiographic findings of children with M. pneumoniae pneumonia correlate well with the clinical features. Consolidative lesions were frequently observed in older children and were associated with more severe clinical features.

Objective To retrospectively evaluate the value of computerized 3D texture analysis for differentiating pulmonary metastases from non-metastatic lesions in pediatric patients with osteosarcoma. Materials and methods This retrospective study was approved by the institutional review board. The study comprised 42 pathologically confirmed pulmonary nodules in 16 children with osteosarcoma who had undergone preoperative computed tomography between January 2009 and December 2014. Texture analysis was performed using an in-house program. Multivariate logistic regression analysis was performed to identify factors for differentiating metastatic nodules from non-metastases. A subgroup analysis was performed to identify differentiating parameters in small non-calcified pulmonary nodules. The receiver operator characteristic curve was created to evaluate the discriminating performance of the established model. Results There were 24 metastatic and 18 non-metastatic lesions. Multivariate analysis revealed that higher mean attenuation (adjusted odds ratio [OR], 1.014, P = 0.003) and larger effective diameter (OR, 1.745, P = 0.012) were significant differentiators. The analysis with small non-calcified pulmonary nodules (7 metastases and 18 non-metastases) revealed significant inter-group differences in various parameters. Logistic regression analysis revealed that higher mean attenuation (OR, 1.007, P = 0.008) was a significant predictor of non-calcified pulmonary metastases. The established logistic regression model of subgroups showed excellent discriminating performance in the ROC analysis (area under the curve, 0.865). Conclusion Pulmonary metastases from osteosarcoma could be differentiated from non-metastases by using computerized texture analysis. Higher mean attenuation and larger diameter were significant predictors for pulmonary metastases, while higher mean attenuation was a significant predictor for small non-calcified pulmonary metastases.

Objective To compare quantitative and qualitative image quality parameters in pediatric abdominopelvic dual-energy CT (DECT) using noise-optimized virtual monoenergetic image (VMI) and conventional VMI at different kiloelectron volt (keV) levels. Materials and Methods Thirty-six consecutive abdominopelvic DECT scans were retrospectively included. Noise-optimized VMI and conventional VMI were reconstructed at seven energy levels, from 40 keV to 100 keV at 10 keV intervals. The contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) of the liver, pancreas, and aorta were objectively measured and compared. Image quality was evaluated subjectively regarding image noise, image blurring of solid organ, bowel image quality and severity of beam-hardening artifacts. Optimal monoenergetic levels in keV for both algorithms were determined based on overall image quality score. Results The maximal CNR and SNR values for all investigated organs were observed at 40 keV in noise-optimized VMI (CNR and SNR of liver, pancreas, aorta in order [CNR; 20.93, 17.34, 46.75: SNR; 37.39, 33.80, 63.21]), at 60–70 keV and at 70 keV in conventional VMI (CNR; 8.12, 5.67, 15.97: SNR; 19.57, 16.66, 26.65). In qualitative image analysis, noise-optimized VMI and conventional VMI showed the best overall image quality scores at 60 keV and at 70 keV, respectively. Noise-optimized VMI at 60 keV showed superior CNRs, SNRs, and overall image quality scores compared to conventional VMI at 70 keV (p < 0.001). Conclusion Optimal energy levels for noise-optimized VMI and conventional VMI were 60 keV and at 70 keV, respectively. Noise-optimized VMI shows superior CNRs, SNRs and subjective image quality over conventional VMI, at the optimal energy level.

Objective To determine the correlation between cerebral blood flow (CBF) on arterial spin labeling (ASL) MRI and the degree of postoperative revascularization assessed on digital subtraction angiography in children with moyamoya disease (MMD). Materials and methods Twenty-one children (9 boys and 12 girls; mean age, 8.4 ± 3.6 years; age range, 3-16 years) with MMD who underwent both pseudocontinuous ASL MRI at 1.5T and catheter angiography before and after superficial temporal artery encephaloduroarteriosynangiosis were included in this retrospective study. The degree of revascularization in the middle cerebral artery (MCA) territory was evaluated on external carotid angiography and was graded on a 3-point scale. On ASL CBF maps, regions of interest were manually drawn over the MCA territory of the operated side at the level of the centrum semi-ovale and over the cerebellum. The normalized CBF (nCBF) was calculated by dividing the CBF of the MCA territory by the CBF of the cerebellum. Changes in nCBFs were calculated by subtracting the preoperative nCBF values from the postoperative nCBF values. The correlation between nCBF changes measured with ASL and the revascularization grade from direct angiography was evaluated. Results The nCBF value on the operated side increased after the operation (p = 0.001). The higher the degree of revascularization, the greater the nCBF change was: poor revascularization (grade 1), -0.043 ± 0.212; fair revascularization (grade 2), 0.345 ± 0.176; good revascularization (grade 3), 0.453 ± 0.182 (p = 0.005, Jockheere-Terpstra test). The interobserver agreement was excellent for the measured CBF values of the three readers (0.91-0.97). Conclusion The nCBF values of the MCA territory obtained from ASL MRI increased after the revascularization procedure in children with MMD, and the degree of nCBF change showed a significant correlation with the degree of collateral formation evaluated via catheter angiography.

Objective To compare image qualities between vendor-neutral and vendor-specific hybrid iterative reconstruction (IR) techniques for abdominopelvic computed tomography (CT) in young patients. Materials and Methods In phantom study, we used an anthropomorphic pediatric phantom, age-equivalent to 5-year-old, and reconstructed CT data using traditional filtered back projection (FBP), vendor-specific and vendor-neutral IR techniques (ClariCT; ClariPI) in various radiation doses. Noise, low-contrast detectability and subjective spatial resolution were compared between FBP, vendor-specific (i.e., iDose1 to 5; Philips Healthcare), and vendor-neutral (i.e., ClariCT1 to 5) IR techniques in phantom. In 43 patients (median, 14 years; age range 1–19 years), noise, contrast-to-noise ratio (CNR), and qualitative image quality scores of abdominopelvic CT were compared between FBP, iDose level 4 (iDose4), and ClariCT level 2 (ClariCT2), which showed most similar image quality to clinically used vendor-specific IR images (i.e., iDose4) in phantom study. Noise, CNR, and qualitative imaging scores were compared using one-way repeated measure analysis of variance. Results In phantom study, ClariCT2 showed noise level similar to iDose4 (14.68–7.66 Hounsfield unit [HU] vs. 14.78–6.99 HU at CT dose index volume range of 0.8–3.8 mGy). Subjective low-contrast detectability and spatial resolution were similar between ClariCT2 and iDose4. In clinical study, ClariCT2 was equivalent to iDose4 for noise (14.26–17.33 vs. 16.01–18.90) and CNR (3.55–5.24 vs. 3.20–4.60) (p > 0.05). For qualitative imaging scores, the overall image quality ([reader 1, reader 2]; 2.74 vs. 2.07, 3.02 vs. 2.28) and noise (2.88 vs. 2.23, 2.93 vs. 2.33) of ClariCT2 were superior to those of FBP (p < 0.05), and not different from those of iDose4 (2.74 vs. 2.72, 3.02 vs. 2.98; 2.88 vs. 2.77, 2.93 vs. 2.86) (p > 0.05). Conclusion Vendor-neutral IR technique shows image quality similar to that of clinically used vendor-specific hybrid IR technique for abdominopelvic CT in young patients.

Xanthogranulomatous cholecystitis (XGC) is a rare form of chronic cholecystitis that is accompanied by xanthomatous histiocytes and chronic inflammation. A 2-month-old boy presented with a right upper abdominal palpable mass. Cholecystectomy with liver wedge resection was done, under the impression that the mass might be a hepatic tumor or liver abscess. Pathologic examination showed XGC with abscess formation. Most cases of XGC were observed in adult and only a few cases were reported in children. We describe a very rare case of XGC in infancy.

Contains fulltext : 118083.pdf (Publisher’s version ) (Open Access) OBJECTIVE: To develop an high resolution computed tomography (HRCT) scoring system for the assessment of bronchopulmonary dysplasia (BPD) and determine its usefulness as compared with the chest radiographic score. MATERIALS AND METHODS: Forty-two very low-birth-weight preterm infants with BPD (25 male, 17 female) were prospectively evaluated with HRCT performed at the mean age of 39.1-week postmenstrual age. Clinical severity of BPD was categorized as mild, moderate or severe. The HRCT score (0-36) of each patient was the sum of the number of bronchopulmonary segments with 1) hyperaeration and 2) parenchymal lesions (linear lesions, segmental atelectasis, consolidation and architectural distortion), respectively. We compared the HRCT scores with the chest radiographic scores (the Toce system) in terms of correlation with clinical severity. RESULTS: The HRCT score had good interobserver (r = 0.969, p < 0.001) and intraobserver (r = 0.986, p < 0.001) reproducibility. The HRCT score showed better correlation (r = 0.646, p < 0.001) with the clinical severity of BPD than the chest radiographic score (r = 0.410, p = 0.007). The hyperaeration score showed better correlation (r = 0.738, p < 0.001) with the clinical severity of BPD than the parenchymal score (r = 0.523, p < 0.001). CONCLUSION: We have developed a new HRCT scoring system for BPD based on the quantitative evaluation of pulmonary abnormalities of BPD consisting of the hyperaeration score and the parenchymal score. The HRCT score shows better correlation with the clinical severity of BPD than the radiographic score.

Advanced virtual monochromatic reconstruction from dual-energy brain CT has not been evaluated in children. To determine the most effective advanced virtual monochromatic imaging energy level for maximizing pediatric brain parenchymal image quality in dual-energy unenhanced brain CT and to compare this technique with conventional monochromatic reconstruction and polychromatic scanning. Using both conventional (Mono) and advanced monochromatic reconstruction (Mono+) techniques, we retrospectively reconstructed 13 virtual monochromatic imaging energy levels from 40 keV to 100 keV in 5-keV increments from dual-source, dual-energy unenhanced brain CT scans obtained in 23 children. We analyzed gray and white matter noise ratios, signal-to-noise ratios and contrast-to-noise ratio, and posterior fossa artifact. We chose the optimal mono-energetic levels and compared them with conventional CT. For Mono+maximum optima were observed at 60 keV, and minimum posterior fossa artifact at 70 keV. For Mono, optima were at 65–70 keV, with minimum posterior fossa artifact at 75 keV. Mono+ was superior to Mono and to polychromatic CT for image-quality measures. Subjective analysis rated Mono+superior to other image sets. Optimal virtual monochromatic imaging using Mono+ algorithm demonstrated better image quality for gray–white matter differentiation and reduction of the artifact in the posterior fossa.

The purpose of this study was to compare free-breathing radially sampled 3D T1-weighted gradient-echo acquisitions (radial volumetric interpolated breath-hold examination [VIBE]) with a T1-weighted turbo spin-echo (TSE) sequence for contrast-enhanced spinal imaging of children with CNS tumors.Twenty-eight consecutively registered children with CNS tumors underwent evaluation of leptomeningeal seeding with 1.5-T MRI that included both radial VIBE and T1-weighted TSE sequences. For qualitative analysis, overall image quality; presence of motion, CSF flow, and radial artifacts; and lesion conspicuity were retrospectively assessed with scoring systems. The signal-intensity uniformity of each sequence was evaluated for quantitative comparison. The acquisition times for each sequence were compared.Images obtained with the radial VIBE sequence had a higher overall image quality score than did T1-weighted TSE images (3.61 ± 0.73 vs 2.80 ± 0.69, p0.001) and lower motion artifact (0.82 ± 0.43 vs 1.29 ± 0.56, p = 0.001) and CSF flow artifact (0 vs 1.68 ± 0.67, p0.001) scores. Radial artifacts were found only on radial VIBE images (1.36 ± 0.31 vs 0, p0.001). In 13 patients with spinal seeding nodules, radial VIBE images showed greater lesion conspicuity than did T1-weighted TSE images (4.23 ± 0.52 vs 2.47 ± 0.57, p = 0.005). Radial VIBE images had diminished signal-intensity variation compared with T1-weighted TSE images in air, spine, and muscle (p0.01). The mean acquisition times were not significantly different between the two sequences (p = 0.117).For pediatric spinal imaging, radial VIBE images had better image quality and lesion conspicuity and fewer CSF and respiratory motion artifacts than did T1-weighted TSE images in a similar acquisition time.

Despite many successes of genome-wide association (GWA) studies, known susceptibility variants identified by GWAS have the modest effect sizes and we met noticeable skepticism about the risk prediction model building with large-scale genetic data. However, in contrast with genetic variants, family history of diseases has been largely accepted as an important risk factor in clinical diagnosis and risk prediction though; complicated structures of family history of diseases have limited their application to clinical use. Here, we develop a new method which enables the incorporation of general family history of diseases with the liability threshold model and a new analysis strategy for risk prediction with penalized regression incorporating large-scale genetic variants and clinical risk factors. An application of our model to type 2 diabetes (T2D) patients in Korean population (1846 cases out of 3692 subjects) demonstrates that SNPs accounts for 28.6% of T2D’s variability and incorporation of family history leads to additional improvement of 5.9%. Our result illustrates that family history of diseases can have an invaluable information for disease prediction and may bridge the gap originated from missing heritability.

Gastric adenomyoma in children is a rare benign tumor composed of a mixture of duct-like epithelial structures with smooth muscle bundles. It has been considered as a subtype of ectopic pancreas because the epithelial component resembles that in pancreatic ducts. However, it is now recognized as an independent pathologic lesion. Gastric adenomyoma is usually asymptomatic but could cause obstruction, inflammation, ulceration, and malignant transformation. Hence, to achieve diagnostic certainty and to control symptoms, complete operative resection is recommended. To the best of our knowledge, this is the first case of gastric adenomyoma mimicking a gastric duplication cyst in children.

Background: Meconium obstruction (MO) of prematurity can result in increased morbidity or mortality and prolonged hospitalization if not diagnosed and treated appropriately. Objectives: The aims of our study were to identify the incidence and risk factors associated with MO and to review the treatment outcomes. Methods: A retrospective analysis was undertaken of 101 extremely low birth weight infants (ELBWIs) who were born between January 1, 2007, and April 1, 2009, at Seoul National University Hospital. Prenatal and neonatal factors were compared between the MO and control groups. The treatment outcomes were also reviewed. Results: Twenty-two (22%) patients were diagnosed as having MO. Eighteen of these patients (82%) had prenatal risk factors for MO. Respiratory distress syndrome was more prevalent in the MO group than in the control group (p = 0.001). Overall, 17 of the 22 patients (77%) were relieved with medical treatment and the rest underwent ileostomy. The times to full enteral feeding did not differ between the medically treated group and the control group. However, the surgically treated group required more time to achieve full enteral feeding, and some patients had persistent gastrointestinal problems. Conclusion: MO is not a rare condition in ELBWIs, and the majority of ELBWIs have prenatal risk factors. Medical management was effective, and medically manageable cases had good prognoses for subsequent feeding, whereas some surgically managed cases had persistent gastrointestinal problems.

This paper describes an optimal traction, braking and steering coordination to improve vehicle lateral stability and manoeuvrability of a six-wheel driving/six-wheel steering (6WD/6WS) vehicle. The optimal coordination controller consists of an upper and lower level controller. The upper level controller determines front, middle steering angle, desired net yaw moment, and longitudinal net force according to the reference velocity and steering angle corresponding to a manual driver. The desired yaw moment is calculated by sliding-mode control theory. Based on the desired longitudinal net force, yaw moment, and tyre force information as inputs from the upper level controller, the lower level controller determines distributed lateral tyre forces and longitudinal tyre force on each wheel in proportion to the size of the friction circle of each wheel. The size of a friction circle is estimated using longitudinal/lateral velocity, yaw rate, wheel torque, and wheel angular velocity. Vehicle–driver–controller closed-loop simulations have been conducted to investigate the improved performance of the proposed optimal coordination controller over a conventional direct yaw moment controller (DYC) of the vehicle equipped with a mechanical drive system.

The acoustic emission (AE) technique is suitable for detecting the presence of thermal and mechanical stress in superconductors, which have adverse effects on the stability of their application systems. However, the detection of AE signals from a HTS tape in a bath of liquid cryogen (such as liquid nitrogen, LN 2 ) has not been reported because of its low signal to noise ratio due to the noise from the boiling liquid cryogen. In order to obtain the AE signals from the HTS tapes during quenching, this study carried out repetitive quench tests for YBCO coated conductor (CC) tapes in a cooling system using solid nitrogen (SN 2 ). This paper examined the performance of the AE sensor in terms of the amplitudes of the AE signals in the SN 2 cooling system.

This paper describes a driving control algorithm based on a skid steering for a robotic vehicle with articulated suspension (RVAS). The RVAS is a kind of unmanned ground vehicle based on a skid steering using an independent in-wheel drive at each wheel. The driving control algorithm consists of four parts: a speed controller for following a desired speed, a lateral motion controller that computes a yaw moment input to track a desired yaw rate or a desired trajectory according to the control mode, a longitudinal tyre force distribution algorithm that determines an optimal desired longitudinal tyre force, and a wheel torque controller that determines a wheel torque command at each wheel in order to keep the slip ratio at each wheel below a limit value as well as to track the desired tyre force. Longitudinal and vertical tyre force estimators are required for the optimal tyre force distribution and wheel slip control. A dynamic model of the RVAS for simulation study is developed and validated using the vehicle test data. Simulation and vehicle tests are conducted in order to evaluate the proposed driving controller. It is found from simulation and vehicle test results that the proposed driving controller provides a satisfactory motion control performance according to the control mode.

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.

The stabilizer of a YBCO coated conductor (CC) plays a very important role in bypassing the over-current and transferring the heat generated at the moment of a fault. Therefore, one of big issues is to determine the best material for the stabilizer and its dimensions for high performance in a HTS power application system. In the case of a superconducting fault current limiter (SFCL), which requires it to react immediately to any fault, the characteristics of the stabilizer are decisive in limiting the fault current and recovering the superconducting properties during and after quenching. This study examined the electrical and thermal behavior of YBCO CCs with various stabilizer thicknesses in fault mode to determine the effects of the stabilizer thickness on the quench/recovery characteristics of YBCO CCs. In particular, the electric field intensity (E) of YBCO CCs in fault mode were calculated and compared with the experimental results.

We have proposed continuously transposed coated conductor (CTCC) in striation for power devices reducing AC loss. It consists of a number of coated conductors with filaments made by striation. The transport of current may distribute non-uniformity in the filament particularly while CTCC conducts AC current. The array of Hall sensors is capable of measuring the current distribution in the filaments and in conductors. However, the search coil array may be applied as ersatz for Hall array in case of existing AC current. The filamentary CTCCs are prepared and the current distribution is then measured by the array of search coils.