JUST-Net: Jointly unrolled cross-domain optimization based spatio-temporal reconstruction network for accelerated 3D myelin water imaging.

PURPOSE: We introduced a novel reconstruction network, jointly unrolled cross-domain optimization-based spatio-temporal reconstruction network (JUST-Net), aimed at accelerating 3D multi-echo gradient-echo (mGRE) data acquisition and improving the quality of resulting myelin water imaging (MWI) maps. METHOD: An unrolled cross-domain spatio-temporal reconstruction network was designed. The main idea is to combine frequency and spatio-temporal image feature representations and to sequentially implement convolution layers in both domains. The k-space subnetwork utilizes shared information from adjacent frames, whereas the image subnetwork applies separate convolutions in both spatial and temporal dimensions. The proposed reconstruction network was evaluated for both retrospectively and prospectively accelerated acquisition. Furthermore, it was assessed in simulation studies and real-world cases with k-space corruptions to evaluate its potential for motion artifact reduction. RESULTS: The proposed JUST-Net enabled highly reproducible and accelerated 3D mGRE acquisition for whole-brain MWI, reducing the acquisition time from fully sampled 15:23 to 2:22 min within a 3-min reconstruction time. The normalized root mean squared error of the reconstructed mGRE images increased by less than 4.0%, and the correlation coefficients for MWI showed a value of over 0.68 when compared to the fully sampled reference. Additionally, the proposed method demonstrated a mitigating effect on both simulated and clinical motion-corrupted cases. CONCLUSION: The proposed JUST-Net has demonstrated the capability to achieve high acceleration factors for 3D mGRE-based MWI, which is expected to facilitate widespread clinical applications of MWI.

MRI-visible Perivascular Spaces in the Neonatal Brain.

Background Mounting evidence suggests that perivascular spaces (PVSs) visible at MRI reflect the function of the glymphatic system. Understanding PVS burden in neonates may guide research on early glymphatic-related pathologic abnormalities. Purpose To perform a visual and volumetric evaluation of PVSs that are visible at MRI in neonates and to evaluate potential associations with maturation, sex, and preterm birth. Materials and Methods In this retrospective study, T2-weighted brain MRI scans in neonates from the Developing Human Connectome Project were used for visual grading (grades 0-4) of PVSs in the basal ganglia (BG) and white matter (WM) and for volumetric analysis of BG PVSs. The BG PVS fraction was obtained by dividing the BG PVS volume by the deep gray matter volume. The association between postmenstrual age at MRI and BG PVS burden was evaluated using linear regression. PVS burden was compared according to sex and preterm birth using the Mann-Whitney test. Results A total of 244 neonates were evaluated (median gestational age at birth, 39 weeks; IQR, 6 weeks; 145 male neonates; 59%), including 88 preterm neonates (median gestational age at birth, 33 weeks; IQR, 6 weeks; 53 male neonates; 60%) and 156 term neonates (median gestational age at birth, 40 weeks; IQR, 2 weeks; 92 male neonates; 59%). For BG PVSs, all neonates showed either grade 0 (90 of 244; 37%) or grade 1 (154 of 244; 63%), and for WM PVSs, most neonates showed grade 0 (227 of 244; 93%). The BG PVS fraction demonstrated a negative relationship with postmenstrual age at MRI (r = -0.008; P < .001). No evidence of differences was found between the sexes for BG PVS volume (P = .07) or BG PVS fraction (P = .28). The BG PVS volume was smaller in preterm neonates than in term neonates (median, 45.3 mm3 [IQR, 15.2 mm3] vs 49.9 mm3 [IQR, 21.3 mm3], respectively; P = .04). Conclusion The fraction of perivascular spaces (PVSs) in the basal ganglia (BG) was lower with higher postmenstrual age at MRI. Preterm birth affected the volume of PVSs in the BG, but sex did not. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Huisman in this issue.

MRI-visible Dilated Perivascular Space in the Brain by Age: The Human Connectome Project.

Background Dilated perivascular spaces (dPVS) are associated with aging and various disorders; however, the effect of age on dPVS burden in young populations and normative data have not been fully evaluated. Purpose To investigate the dPVS burden and provide normative data according to age in a healthy population, including children. Materials and Methods In this retrospective study, three-dimensional T2-weighted brain MRI scans from the Human Connectome Project data sets were used for visual grading (grade 0, 1, 2, 3, 4 for 0, 1-10, 11-20, 21-40, and >40 dPVS on a single section of either hemispheric region) and automated volumetry of dPVS in basal ganglia (BGdPVS) and white matter (WMdPVS). Linear and nonlinear regression were performed to assess the association of dPVS volume with age. Optimal cutoff ages were determined with use of the maximized continuous-scale C-index. Participants were grouped by cutoff values. Linear regression was performed to assess the age-dPVS volume relationship in each age group. Normative data of dPVS visual grades were provided per age decade. Results A total of 1789 participants (mean age, 35 years; age range, 8-100 years; 1006 female participants) were evaluated. Age was related to dPVS volume in all regression models (R2 range, 0.41-0.55; P < .001). Age-dPVS volume relationships were altered at the mid-30s and age 55 years; BGdPVS and WMdPVS volumes negatively correlated with age until the mid-30s (ß, -1.2 and -7.8), then positively until age 55 years (ß, 3.3 and 54.1) and beyond (ß, 3.9 and 42.8; P < .001). The 90th percentile for dPVS grades was grade 1 for age 49 years and younger, grade 2 for age 50-69 years, and grade 3 for age 70 years and older (overall, grade 2) for BGdPVS, and grade 3 for age 49 years and younger and grade 4 for age 50 years and older (overall, grade 3) for WMdPVS. Conclusion Dilated perivascular spaces (dPVS) showed a biphasic volume pattern with brain MRI, lower volumes until the mid-30s, then higher afterward. Grades of 3 or higher and 4 might be considered pathologic dPVS in basal ganglia and white matter, respectively. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Bapuraj and Chaudhary in this issue.

3D MR fingerprinting-derived myelin water fraction characterizing brain development and leukodystrophy.

BACKGROUND: Magnetic resonance fingerprinting (MRF) enables fast myelin quantification via the myelin water fraction (MWF), offering a noninvasive method to assess brain development and disease. However, MRF-derived MWF lacks histological evaluation and remains unexamined in relation to leukodystrophy. This study aimed to access MRF-derived MWF through histology in mice and establish links between myelin, development, and leukodystrophy in mice and children, demonstrating its potential applicability in animal and human studies. METHODS: 3D MRF was performed on normal C57BL/6 mice with different ages, megalencephalic leukoencephalopathy with subcortical cyst 1 wild type (MLC1 WT, control) mice, and MLC 1 knock-out (MLC1 KO, leukodystrophy) mice using a 3 T MRI. MWF values were analyzed from 3D MRF data, and histological myelin quantification was carried out using immunohistochemistry to anti-proteolipid protein (PLP) in the corpus callosum and cortex. The associations between 'MWF and PLP' and 'MWF and age' were evaluated in C57BL/6 mice. MWF values were compared between MLC1 WT and MLC1 KO mice. MWF of normal developing children were retrospectively collected and the association between MWF and age was assessed. RESULTS: In 35 C57BL/6 mice (age range; 3 weeks-48 weeks), MWF showed positive relations with PLP immunoreactivity in the corpus callosum (ß = 0.0006, P = 0.04) and cortex (ß = 0.0005, P = 0.006). In 12-week-old C57BL/6 mice MWF showed positive relations with PLP immunoreactivity (ß = 0.0009, P = 0.003, R2 = 0.54). MWF in the corpus callosum (ß = 0.0022, P < 0.001) and cortex (ß = 0.0010, P < 0.001) showed positive relations with age. Seven MLC1 WT and 9 MLC1 KO mice showed different MWF values in the corpus callous (P < 0.001) and cortex (P < 0.001). A total of 81 children (median age, 126 months; range, 0-199 months) were evaluated and their MWF values according to age showed the best fit for the third-order regression model (adjusted R2 range, 0.44-0.94, P < 0.001). CONCLUSION: MWF demonstrated associations with histologic myelin quantity, age, and the presence of leukodystrophy, underscoring the potential of 3D MRF-derived MWF as a rapid and noninvasive quantitative indicator of brain myelin content in both mice and humans.

A regional brain volume-based age prediction model for neonates and the derived brain maturation index.

OBJECTIVE: To develop a postmenstrual age (PMA) prediction model based on segmentation volume and to evaluate the brain maturation index using the proposed model. METHODS: Neonatal brain MRIs without clinical illness or structural abnormalities were collected from four datasets from the Developing Human Connectome Project, the Catholic University of Korea, Hammersmith Hospital (HS), and Dankook University Hospital (DU). T1- and T2-weighted images were used to train a brain segmentation model. Another model to predict the PMA of neonates based on segmentation data was developed. Accuracy was assessed using mean absolute error (MAE), root mean square error (RMSE), and mean error (ME). The brain maturation index was calculated as the difference between the PMA predicted by the model and the true PMA, and its correlation with postnatal age was analyzed. RESULTS: A total of 247 neonates (mean gestation age 37 ± 4 weeks; range 24-42 weeks) were included. Thirty-one features were extracted from each neonate and the three most contributing features for PMA prediction were the right lateral ventricle, left caudate, and corpus callosum. The predicted and true PMA were positively correlated (coefficient = 0.88, p < .001). MAE, RMSE, and ME of the external dataset of HS and DU were 1.57 and 1.33, 1.79 and 1.37, and 0.37 and 0.06 weeks, respectively. The brain maturation index negatively correlated with postnatal age (coefficient = - 0.24, p < .001). CONCLUSION: A model that calculates the regional brain volume can predict the PMA of neonates, which can then be utilized to show the brain maturation degree. CLINICAL RELEVANCE STATEMENT: A brain maturity index based on regional volume of neonate's brain can be used to measure brain maturation degree, which can help identify the status of early brain development. KEY POINTS: • Neonatal brain MRI segmentation model could be used to assess neonatal brain maturation status. • A postmenstrual age (PMA) prediction model was developed based on a neonatal brain MRI segmentation model. • The brain maturation index, derived from the PMA prediction model, enabled the estimation of the neonatal brain maturation status.

Highly accelerated 3D MPRAGE using deep neural network-based reconstruction for brain imaging in children and young adults.

OBJECTIVES: This study aimed to accelerate the 3D magnetization-prepared rapid gradient-echo (MPRAGE) sequence for brain imaging through the deep neural network (DNN). METHODS: This retrospective study used the k-space data of 240 scans (160 for the training set, mean ± standard deviation age, 93 ± 80 months, 94 males; 80 for the test set, 106 ± 83 months, 44 males) of conventional MPRAGE (C-MPRAGE) and 102 scans (77 ± 74 months, 52 males) of both C-MPRAGE and accelerated MPRAGE. All scans were acquired with 3T scanners. DNN was developed with simulated-acceleration data generated by under-sampling. Quantitative error metrics were compared between images reconstructed with DNN, GRAPPA, and E-SPIRIT using the paired t-test. Qualitative image quality was compared between C-MPRAGE and accelerated MPRAGE reconstructed with DNN (DNN-MPRAGE) by two readers. Lesions were segmented and the agreement between C-MPRAGE and DNN-MPRAGE was assessed using linear regression. RESULTS: Accelerated MPRAGE reduced scan times by 38% compared to C-MPRAGE (142 s vs. 320 s). For quantitative error metrics, DNN showed better performance than GRAPPA and E-SPIRIT (p < 0.001). For qualitative evaluation, overall image quality of DNN-MPRAGE was comparable (p > 0.999) or better (p = 0.025) than C-MPRAGE, depending on the reader. Pixelation was reduced in DNN-MPRAGE (p < 0.001). Other qualitative parameters were comparable (p > 0.05). Lesions in C-MPRAGE and DNN-MPRAGE showed good agreement for the dice similarity coefficient (= 0.68) and linear regression (R2 = 0.97; p < 0.001). CONCLUSIONS: DNN-MPRAGE reduced acquisition time by 38% and revealed comparable image quality to C-MPRAGE. KEY POINTS: • DNN-MPRAGE reduced acquisition times by 38%. • DNN-MPRAGE outperformed conventional reconstruction on accelerated scans (SSIM of DNN-MPRAGE = 0.96, GRAPPA = 0.43, E-SPIRIT = 0.88; p < 0.001). • Compared to C-MPRAGE scans, DNN-MPRAGE showed improved mean scores for overall image quality (2.46 vs. 2.52; p < 0.001) or comparable perceived SNR (2.56 vs. 2.58; p = 0.08).

Accelerated 3D T2-weighted images using compressed sensing for pediatric brain imaging.

PURPOSE: The purpose of this study was to compare the image quality of the 3D T2-weighted images accelerated using conventional method (CAI-SPACE) with the images accelerated using compressed sensing (CS-SPACE) in pediatric brain imaging. METHODS: A total of 116 brain MRI (53 with CAI-SPACE and 63 with CS-SPACE) were obtained from children 16 years old or younger. Quantitative image quality was evaluated using the apparent signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The sequences were qualitatively evaluated for overall image quality, general artifact, cerebrospinal fluid (CSF)-related artifact, and grey-white matter differentiation. The two sequences were compared for the total and two age groups (< 24 months vs. ≥ 24 months). RESULTS: Compressed sensing application in 3D T2-weighted imaging resulted in 8.5% reduction in scanning time. Quantitative image quality analysis showed higher apparent SNR (median [Interquartile range]; 29 [25] vs. 23 [14], P = 0.005) and CNR (0.231 [0.121] vs. 0.165 [0.120], P = 0.027) with CS-SPACE compared to CAI-SPACE. Qualitative image quality analysis showed better image quality with CS-SPACE for general (P = 0.024) and CSF-related artifact (P < 0.001). CSF-related artifacts reduction was prominent in the older age group (≥ 24 months). Overall image quality (P = 0.162) and grey-white matter differentiation (P = 0.397) were comparable between CAI-SPACE and CS-SPACE. CONCLUSION: Compressed sensing application in 3D T2-weighted images modestly reduced acquisition time and lowered CSF-related artifact compared to conventional images of the pediatric brain.

Brain MRI radiomics analysis may predict poor psychomotor outcome in preterm neonates.

OBJECTIVES: This study aimed to apply a radiomics approach to predict poor psychomotor development in preterm neonates using brain MRI. METHODS: Prospectively enrolled preterm neonates underwent brain MRI near or at term-equivalent age and neurodevelopment was assessed at a corrected age of 12 months. Two radiologists visually assessed the degree of white matter injury. The radiomics analysis on white matter was performed using T1-weighted images (T1WI) and T2-weighted images (T2WI). A total of 1906 features were extracted from the images and the minimum redundancy maximum relevance algorithm was used to select features. A prediction model for the binary classification of the psychomotor developmental index was developed and eightfold cross-validation was performed. The diagnostic performance of the model was evaluated using the AUC with and without including significant clinical and DTI parameters. RESULTS: A total of 46 preterm neonates (median gestational age, 29 weeks; 26 males) underwent brain MRI (median corrected gestational age, 37 weeks). Thirteen of 46 (28.3%) neonates showed poor psychomotor outcomes. There was one neonate among 46 with moderate to severe white matter injury on visual assessment. For the radiomics analysis, twenty features were selected for each analysis. The AUCs of prediction models based on T1WI, T2WI, and both T1WI and T2WI were 0.925, 0.834, and 0.902. Including gestational age or DTI parameters did not improve the prediction performance of T1WI. CONCLUSIONS: A radiomics analysis of white matter using early T1WI or T2WI could predict poor psychomotor outcomes in preterm neonates. KEY POINTS: • Radiomics analysis on T1-weighted images of preterm neonates showed the highest diagnostic performance (AUC, 0.925) for predicting poor psychomotor outcomes. • In spite of 45 of 46 neonates having no significant white matter injury on visual assessment, the radiomics analysis of early brain MRI showed good diagnostic performance (sensitivity, 84.6%; specificity, 78.8%) for predicting poor psychomotor outcomes. • Radiomics analysis on early brain MRI can help to predict poor neurodevelopmental outcomes in preterm neonates.

Texture analysis of deep medullary veins on susceptibility-weighted imaging in infants: evaluating developmental and ischemic changes.

OBJECTIVE: Susceptibility-weighted imaging (SWI) can be used to evaluate deep medullary veins (DMVs). This study aimed to apply texture analysis on SWI to evaluate developmental and ischemic changes of DMV in infants. METHODS: A total of 38 infants with normal brain MRI (preterm [n = 12], term-equivalent age [TEA] [n = 18], and term [n = 8]) and seven infants with ischemic injury (preterm [n = 2], TEA [n = 1], and term [n = 4]) were included. Regions of interests were manually drawn to include DMVs. First-order texture parameters including entropy, skewness, and kurtosis were derived from SWI. The parameters were compared between groups according to age and presence of ischemic injury. A regression analysis was performed to correlate postmenstrual age (PMA) and parameters. A ROC analysis was performed to differentiate ischemic infants from normal infants. RESULTS: Among parameters, entropy showed a significant difference between the age groups (preterm vs. TEA vs. term; 5.395 vs. 4.885 vs. 4.883, p = 0.001). There was a significant positive relationship between PMA and entropy (R square = 0.402, p < 0.001). Skewness was significantly higher in the ischemic group compared with that in the normal group (1.37 vs. 0.70, p = 0.001). The ROC on skewness resulted in an AUC of 0.87 (accuracy, 83.2%) for differentiating infants with ischemic injury. CONCLUSION: A texture analysis of DMVs on SWI showed differences according to age and presence of ischemic injury. The texture parameters can potentially be used as quantitative markers for differentiating infants with ischemic injury through DMV changes. KEY POINTS: • The DMV structure of the infant brain could be quantified on SWI with texture analysis. • Entropy from texture analysis on SWI increased as infants got older. • Normal and ischemic injured infants could be differentiated with a cutoff value of 1.025 for skewness.

Analysis of Optical Plasma Monitoring in Plasma-Enhanced Atomic Layer Deposition Process of Al2O3.

A noninvasive, optical plasma monitoring method in plasma-enhanced atomic layer deposition (PEALD) process for nanoscale water vapor barrier film is presented. Any equipment malfunction, as well as a deviation in the condition of individual components can easily jeopardize the process result. Al2O3 deposition process was employed in this research as a test vehicle, and high-speed optical plasma monitoring was demonstrated. It is shown that optical plasma monitoring is useful for not only measuring plasma pulses in real time, but also for the detection of any variation in plasma condition which enables inferring plasma dynamics for advanced process control in nanoscale thin film deposition process.

Ipsilateral Hypertrophy of the Mastoid Process in Surgical Cases of Congenital Muscular Torticollis.

OBJECTIVE: This study was to investigate ipsilateral hypertrophy of the mastoid process in the patients with congenital muscular torticollis (CMT). DESIGN: Retrospective cross-sectional study. PATIENTS: Children with CMT. METHODS: A total of 212 surgical cases of patients with CMT (age: 50.9 ± 44.3 months) and 212 age- and gender-matched controls (age: 50.4 ± 44.2 months) were included. The mastoid process volume was calculated and compared for both groups on the computed tomography axial images. A linear regression analysis was performed between the age and the intrasubject volume difference in the mastoid process. RESULTS: The volume of the mastoid process in the CMT side was significantly larger than that of the non-CMT side in the CMT group (32.2 ± 30.3 cm3 vs 21.9 ± 22.8 cm3; P < .001). In the control group, there was no significant difference between the volume of the right and left mastoid process (21.6 ± 24.6 cm3 vs 21.2 ± 23.8 cm3; P = .472). The intrasubject volume difference in the mastoid process in the CMT group showed a linear increase with the age (adjusted R2 = 0.286; P < .001), and the volumetric asymmetry of the mastoid process became more severe over age compared to the control group. CONCLUSION: We showed ipsilateral hypertrophy of the mastoid process in patients with CMT and demonstrated that the volumetric asymmetry increased with age.

Head CT: Image quality improvement with ASIR-V using a reduced radiation dose protocol for children.

OBJECTIVE: To investigate the quality of images reconstructed with adaptive statistical iterative reconstruction V (ASIR-V), using pediatric head CT protocols. METHODS: A phantom was scanned at decreasing 20% mA intervals using our standard pediatric head CT protocols. Each study was then reconstructed at 10% ASIR-V intervals. After the phantom study, we reduced mA by 10% in the protocol for <3-year-old patients and applied 30% ASIR-V and by 30% in the protocol for 3- to 15-year-old patients and applied 40% ASIR-V. RESULTS: Increasing the percentage of ASIR-V resulted in lower noise and higher contrast-to-noise ratio (CNR) and preserved spatial resolution in the phantom study. Compared to a conventional-protocol, reduced-dose protocol with ASIR-V achieved 12.8% to 34.0% of dose reduction and showed images of lower noise (9.22 vs. 10.73, P = 0.043) and higher CNR in different levels (centrum semiovale, 2.14 vs. 1.52, P = 0.003; basal ganglia, 1.46 vs. 1.07, P = 0.001; and cerebellum, 2.18 vs. 1.33, P < 0.001). Qualitative analysis showed higher gray-white matter differentiation and sharpness and preserved overall diagnostic quality in the images with ASIR-V. CONCLUSIONS: Use of ASIR-V allowed a 12.8% to 34.0% dose reduction in each age group with potential to improve image quality. KEY POINTS: • It is possible to reduce radiation dose and improve image quality with ASIR-V. • We improved noise and CNR and decreased radiation dose. • Sharpness improved with ASIR-V. • Total radiation dose was decreased by 12.8% to 34.0%.

Altered intrinsic brain activity after chemotherapy in patients with gastric cancer: A preliminary study.

OBJECTIVES: To characterize the pattern of altered intrinsic brain activity in gastric cancer patients after chemotherapy (CTx). METHODS: Patients before and after CTx (n = 14) and control subjects (n = 11) underwent resting-state functional MRI (rsfMRI) at baseline and 3 months after CTx. Regional homogeneity (ReHo), amplitude of low-frequency fluctuation (ALFF), and fractional ALFF (fALFF) were calculated and compared between the groups using the two-sample t test. Correlation analysis was also performed between rsfMRI values (i.e., ReHo, ALFF, and fALFF) and neuropsychological test results. RESULTS: Patients showed poor performance in verbal memory and executive function and decreased rsfMRI values in the frontal areas even before CTx and showed decreased attention/working memory and executive function after CTx compared to the control subjects. In direct comparison of values before and after CTx, there were no significant differences in neuropsychological test scores, but decreased rsfMRI values were observed at the frontal lobes and right cerebellar region. Among rsfMRI values, lower ALFF in the left inferior frontal gyrus was significantly associated with poor performance of the executive function test. CONCLUSIONS: We observed decreased attention/working memory and executive function that corresponded to the decline of frontal region activation in gastric cancer patients who underwent CTx. KEY POINTS: • Intrinsic brain activity of gastric cancer patients after chemotherapy was described. • Brain activity and neuropsychological test results were correlated. • Working memory and executive function decreased after chemotherapy. • Decreased cognitive function corresponded to decreased activation of the frontal region.

Quantification of myelin in children using multiparametric quantitative MRI: a pilot study.

PURPOSE: The purpose of this study was to evaluate the usefulness of multiparametric quantitative MRI for myelination quantification in children. METHODS: We examined 22 children (age 0-14 years) with multiparametric quantitative MRI. The total volume of myelin partial volume (Msum), the percentage of Msum within the whole brain parenchyma (Mbpv), and the percentage of Msum within the intracranial volume (Micv) were obtained. Four developmental models of myelin maturation (the logarithmic, logistic, Gompertz, and modified Gompertz models) were examined to find the most representative model of the three parameters. We acquired myelin partial volume values in different brain regions and assessed the goodness of fit for the models. RESULTS: The ranges of Msum, Mbpv, and Micv were 0.8-160.9 ml, 0.2-13%, and 0.0-11.6%, respectively. The Gompertz model was the best fit for the three parameters. For developmental model analysis of myelin partial volume in each brain region, the Gompertz model was the best-fit model for pons (R 2 = 74.6%), middle cerebeller peduncle (R 2 = 76.4%), putamen (R2 = 95.8%), and centrum semiovale (R 2 = 77.7%). The logistic model was the best-fit model for the genu and splenium of the corpus callosum (R 2 = 79.7-93.6%), thalamus (R 2 = 81.7%), and frontal, parietal, temporal, and occipital white matter (R 2 = 92.5-96.5%). CONCLUSIONS: Multiparametric quantitative MRI depicts the normal developmental pattern of myelination in children. It is a potential tool for research studies on pediatric brain development evaluation.

Ultrasound Elastography of the Neonatal Brain: Preliminary Study.

OBJECTIVES: To determine the ultrasound elasticity of the brain in neonates METHODS: Strain elastography was performed in 21 healthy neonates (mean gestational age [GA], 34 weeks; range, 28-40 weeks). Elastographic scores were assigned to the following structures on a 5-point color scale (1-5): ventricle, periventricular white matter, caudate, subcortical, cortical gray matter, and subdural space. Three elastographic images were evaluated in each patient, and median elastographic scores were calculated. The scores were compared between regions and were correlated with the corrected GA. Interobserver agreements for assignment of elastographic scores were analyzed. RESULTS: The ventricle and subdural space showed an elasticity score of 1 in all patients. The cortical gray matter (median, 3.0; first-third quartiles, 2.33-3.33) showed higher elasticity compared to the periventricular white mater (4.0; 3.00-4.00; P < .001), caudate (4.3; 3.67-4.67; P < .001), and subcortical white matter (4.0; 4.00-4.00; P < .001). The caudate showed lower elasticity compared to periventricular white matter (P = .004). The periventricular white matter showed higher elasticity compared to subcortical white matter (P = .009). There was a positive trend between the corrected GA and cortical gray matter elastographic score (γ = 0.376; P = .093). Interobserver agreement was moderate to almost perfect (κ = 0.53-0.89). CONCLUSIONS: Neonatal intracranial regions showed different elasticity, which could be accessed by strain elastography. These normal findings should prompt future studies investigating the use of ultrasound elastography in the neonatal brain.

Conversion and reliability of two urological grading systems in infants: the Society for Fetal Urology and the urinary tract dilatation classifications system.

BACKGROUND: The urinary tract dilation (UTD) classification system was proposed in 2014. OBJECTIVE: To evaluate the correspondence and reliability of two US grading systems for postnatal urinary tract dilatation in infants: the Society for Fetal Urology (SFU) and the UTD systems. MATERIALS AND METHODS: We assessed 180 kidneys in infants younger than 1 year. Four radiologists assessed the kidneys twice using both the SFU system (grades 0 to 4) and the UTD system (grades normal, P1, P2, P3). The SFU system was re-categorized into SFU-A (grades 0, 1-2, 3, 4) and into SFU-B (grades 0-1, 2, 3, 4). The Cohen kappa statistic was used for estimating agreement of both UTD-SFU-A and UTD-SFU-B. RESULTS: The Cohen kappa was significantly higher between UTD and SFU-B as compared to the UTD and SFU-A (0.75 vs. 0.50, P < 0.001). Intra-observer agreement was similar for the two grading systems (SFU 0.64-0.88 vs. UTD 0.48-0.92, P = 0.050-0.885). SFU grades 2 and 3 showed fair to moderate inter-observer agreement and corresponding UTD grades P1 and P2 showed moderate to substantial agreement. The overall inter-observer agreement was significantly higher for the UTD system than for the SFU system during the first assessment (95% confidence interval [CI]: right kidney, -0.069 to -0.062; left kidney, -0.048 to -0.043). CONCLUSION: Correspondence between the systems was poor using a recommended re-categorization (SFU-A). An alternative re-categorization (SFU-B) was found to be more appropriate for establishing correspondence between the systems. Both systems were reliable, with good intra- and inter-observer agreement for the assessment of infant kidneys, but the UTD system had better inter-observer agreement.

Quantitative computed tomography assessment of graft-versus-host disease-related bronchiolitis obliterans in children: A pilot feasibility study.

OBJECTIVE: To suggest a simple method that can quantify air trapping from chest CT in children with graft-versus-host disease (GVHD)-related bronchiolitis obliterans (BO). METHODS: This institutional review board-approved retrospective study included eight GVHD-related BO patients (age, 6 - 17 years) who underwent both 31 CTs of variable settings and pulmonary function tests (PFT). The attenuation values of lung parenchyma in normal (An) and air trapping (Aa) areas were obtained. Individualized threshold [(An + Aa)/2] and fixed threshold of -950 HU were set for air trapping quantification. Spearman correlation analysis and generalized linear mixed models were used for statistical analysis. RESULTS: The mean value of individualized threshold was -830.2 ± 48.3 HU. The mean air trapping lung volume percentage with individualized threshold and -950 HU were 45.4 ± 18.9% and 1.4 ± 1.9%, respectively. The air trapping lung volume percentage with individualized threshold showed a significant negative correlation with the PFT of FEV1/FVC% in all data (γ = -0.795, P < .001) and in the correction of repetition (γ = -0.837, P = .010). CONCLUSIONS: We suggest a simple and individualized threshold attenuation setting method for air trapping quantification insusceptible to CT imaging protocols or respiratory phase control in children with GVHD-related BO. KEY POINTS: • Simple and individualized threshold attenuation setting for air trapping quantification is possible. • Individualized threshold attenuation setting is insusceptible to CT imaging protocols or respiratory phase control. • CT air trapping quantification correlates with PFT of pulmonary obstruction.

Prepubertal Testicular Teratomas and Epidermoid Cysts: Comparison of Clinical and Sonographic Features.

OBJECTIVES: To evaluate clinical and sonographic features of testicular teratomas and epidermoid cysts in children and to assess differential points of immature teratomas from benign counterparts. METHODS: We retrospectively reviewed testicular teratomas and epidermoid cysts in children. Age at surgery, α-fetoprotein (AFP) level, and sonographic findings, including components (mainly cystic, mainly solid, or mixed), presence of calcification, and size, were reviewed. RESULTS: Nineteen cases were included, with 10 mature teratomas, 3 immature teratomas, and 6 epidermoid cysts. On sonography, most of the teratomas (n = 9) had mixed components, with 2 mainly cystic and 2 mainly solid lesions. The 2 mainly cystic teratomas underwent follow-up sonography and showed component changes to mainly solid. Compared to epidermoid cysts, teratomas were larger (P = .029) with less cystic components (P = .046). All 3 immature teratomas showed mixed components with calcification. In differentiating immature from benign teratomas, immature teratomas were larger (P= .047) in younger children (P= .008) with higher AFP levels (P= .023). The optimal cutoff values for diagnosing immature teratomas were 8 months of age, 23 ng/mL in AFP level, and 2.5 cm in size, with 100% sensitivity and 89.5% accuracy rates. However, sonographic features, including tumor components and presence of calcification, were not helpful for differentiating immature teratomas. CONCLUSIONS: Testicular masses in children younger than 8 months with AFP levels higher than 23 ng/mL and size larger than 2.5 cm need to be considered for orchiectomy rather than testis-sparing tumorectomy because of the increased frequency of immature teratomas versus mature teratomas or epidermoid cysts.

Optimal Filum Terminale Thickness Cutoff Value on Sonography for Lipoma Screening in Young Children.

OBJECTIVES: The purpose of this study was to evaluate the normal thickness of the filum terminale on sonography and suggest an optimal cutoff value for filum terminale lipoma screening in young children. METHODS: We retrospectively reviewed lumbosacral sonograms and magnetic resonance images from children younger than 36 months that were obtained between January 2013 and June 2014. The filum terminale thickness on sonography and the presence of fat in the filum terminale on magnetic resonance imaging were evaluated. RESULTS: From 111 children (mean age ± SD, 3.6 ± 3.0 months), 49 did not have abnormal lesions (normal group), and 62 had fat infiltration in the filum terminale (lipoma group). The filum terminale was thicker in the lipoma group than the normal group (1.5 ± 0.5 versus 0.9 ± 0.2 mm; P < .001). Filum terminale thickness also showed significance in a multivariable analysis with sex and age (odds ratio per 0.1-mm unit, 2.754; P < .001) and in propensity score matching for age (P < .001). The optimal cutoff value for filum terminale lipoma screening was 1.1 mm, with 94% sensitivity and 86% specificity. CONCLUSIONS: The conventional cutoff value of 2 mm for a thickened filum terminale on sonography can be too thick. We suggest an optimal cutoff value of 1.1 mm for lipoma screening in young children.

Radiation dose and image quality in pediatric chest CT: effects of iterative reconstruction in normal weight and overweight children.

BACKGROUND: New CT reconstruction techniques may help reduce the burden of ionizing radiation. OBJECTIVE: To quantify radiation dose reduction when performing pediatric chest CT using a low-dose protocol and 50% adaptive statistical iterative reconstruction (ASIR) compared with age/gender-matched chest CT using a conventional dose protocol and reconstructed with filtered back projection (control group) and to determine its effect on image quality in normal weight and overweight children. MATERIALS AND METHODS: We retrospectively reviewed 40 pediatric chest CT (M:F = 21:19; range: 0.1-17 years) in both groups. Radiation dose was compared between the two groups using paired Student's t-test. Image quality including noise, sharpness, artifacts and diagnostic acceptability was subjectively assessed by three pediatric radiologists using a four-point scale (superior, average, suboptimal, unacceptable). RESULTS: Eight children in the ASIR group and seven in the control group were overweight. All radiation dose parameters were significantly lower in the ASIR group (P < 0.01) with a greater than 57% dose reduction in overweight children. Image noise was higher in the ASIR group in both normal weight and overweight children. Only one scan in the ASIR group (1/40, 2.5%) was rated as diagnostically suboptimal and there was no unacceptable study. CONCLUSION: In both normal weight and overweight children, the ASIR technique is associated with a greater than 57% mean dose reduction, without significantly impacting diagnostic image quality in pediatric chest CT examinations. However, CT scans in overweight children may have a greater noise level, even when using the ASIR technique.