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Background and Purpose: It can be challenging to depict brain volume abnormalities in the pediatric population on magnetic resonance imaging (MRI). The aim of the study was to evaluate the inter-radiologist reliability in brain MRI interpretation, including brain volume assessment and the efficiency of an automated brain segmentation., Materials and Methods: We performed a single-center prospective study including 44 patients aged six months to five years recruited from the University Hospital, having a 1.5T brain MRI using a MP2RAGE sequence. All MRI were randomly and blindly reviewed by one junior and two senior pediatric radiologists. Inter-observer agreements were assessed using Fleiss' kappa coefficient. Brain volumetry (total intracranial volume (TIV), brain parenchyma, and cerebrospinal fluid volumes) was estimated using the MorphoBox prototype. Clinical head circumference (HC) and z scores were reported. A Pearson correlation coefficient was calculated between brain volumes with HC., Results: Twenty-four brain MRI examinations were normal and twenty were pathological. Brain volume abnormalities were poorly detected by junior and senior radiologists: sensitivities 16.67% [confidence interval 4.7-44.8], 33.33% [13-60] and 30.7% [12-58] and specificities 93.75% [79-98], 84.38% [68-93] and 77% [60-88], respectively. Brain volume apart, interobserver kappa coefficients were 0.93 between junior and seniors as well as between seniors. Brain volumes were significantly correlated with HC (P<0.0001). In patients with normal MRI, brain parenchyma volumes increased regularly with age. Low brain volume was easier to identify with automated quantification., Conclusion: Brain volume was poorly appreciated by radiologists. The fully automated brain segmentation used can provide quantitative data to better diagnose, describe, and follow-up brain volume abnormalities., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Objectives: This study introduced a tailored MP2RAGE-based brain acquisition for a comprehensive assessment of the normal maturing brain., Methods: Seventy normal patients (35 girls and 35 boys) from 1 to 16 years of age were recruited within a prospective monocentric study conducted from a single University Hospital. Brain MRI examinations were performed at 1.5 T using a 20-channel head coil and an optimized 3D MP2RAGE sequence with a total acquisition time of 6:36 min. Automated 38 region segmentation was performed using the MorphoBox (template registration, bias field correction, brain extraction, and tissue classification) which underwent a major adaptation of three age-group T1-weighted templates. Volumetry and T1 relaxometry reference ranges were established using a logarithmic model and a modified Gompertz growth respectively., Results: Detailed automated brain segmentation and T1 mapping were successful in all patients. Using these data, an age-dependent model of normal brain maturation with respect to changes in volume and T1 relaxometry was established. After an initial rapid increase until 24 months of life, the total intracranial volume was found to converge towards 1400 mL during adolescence. The expected volumes of white matter (WM) and cortical gray matter (GM) showed a similar trend with age. After an initial major decrease, T1 relaxation times were observed to decrease progressively in all brain structures. The T1 drop in the first year of life was more pronounced in WM (from 1000-1100 to 650-700 ms) than in GM structures., Conclusion: The 3D MP2RAGE sequence allowed to establish brain volume and T1 relaxation time normative ranges in pediatrics., Key Points: • The 3D MP2RAGE sequence provided a reliable quantitative assessment of brain volumes and T1 relaxation times during childhood. • An age-dependent model of normal brain maturation was established. • The normative ranges enable an objective comparison to a normal cohort, which can be useful to further understand, describe, and identify neurodevelopmental disorders in children.

Imaging plays a major role in the comprehensive assessment of posterior fossa tumor in children (PFTC). The objective is to propose a global method relying on the combined analysis of radiological, clinical and epidemiological criteria, (taking into account the child's age and the topography of the lesion) in order to improve our histological approach in imaging, helping the management and approach for surgeons in providing information to the patients' parents. Infratentorial tumors are the most frequent in children, representing mainly medulloblastoma, pilocytic astrocytoma and brainstem glioma. Pre-surgical identification of the tumor type and its aggressiveness could be improved by the combined analysis of key imaging features with epidemiologic data., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Background: Pediatric magnetic resonance imaging (MRI) can be stressful. Mock MR scanners have been proven to be effective in avoiding the use of general anesthesia., Objectives: We prospectively evaluated the impact of a teddy bear-scale model of a mock MR scanner on the anxiety experienced by parents and their children during MRI without general anesthesia ., Materials and Methods: A 1-year prospective study before and after the installation of a mock scanner in a Pediatric Radiology Department of a university hospital. Anxiety levels were self-estimated by children ages 4 to 16 years and by the parents with a visual analogue scale (from 0, completely relaxed, to 100, extremely stressed) at three moments: in the waiting room, in the preparation room after an explanation by the MRI technologists, and at the issue of the MR acquisition images. Two groups were tested: one with a mock MR scanner, the other without. Analysis of variance (ANOVA) and Fisher exact tests were performed. Motion artifacts were studied., Results: Ninety-one children and their parents were included. The median age was 8 years (standard deviation [SD]=2). In the post mock period, the ambiance of the preparation room was considered by children as significantly more relaxing in 50% vs. 20% (P=0.004) and the anxiety level of children was significantly lower after the explanation, particularly in girls, but unchanged for their parents. The anxiety levels at the end of the examination were significantly lower for parents. The motion artifacts rate was lower (1.7% vs. 4.7%, P=0.04)., Conclusion: A mock scanner was an efficient tool to improve efficiency of the explanation and to decrease anxiety in children and motion artifacts in pediatric MRI.

Background and Purpose: Automated synthetic magnetic resonance imaging (MRI) provides qualitative, weighted image contrasts as well as quantitative information from one scan and is well-suited for various applications such as analysis of white matter disorders. However, the synthesized contrasts have been poorly evaluated in pediatric applications. The purpose of this study was to compare the image quality of synthetic T2 to conventional turbo spin-echo (TSE) T2 in pediatric brain MRI., Materials and Methods: This was a mono-center prospective study. Synthetic and conventional MRI acquisitions at 1.5 Tesla were performed for each patient during the same session using a prototype accelerated T2 mapping sequence package (TA synthetic =3:07min, TA conventional =2:33min). Image sets were blindly and randomly analyzed by pediatric neuroradiologists. Global image quality, morphologic legibility of standard structures and artifacts were assessed using a 4-point Likert scale. Inter-observer kappa agreements were calculated. The capability of the synthesized contrasts and conventional TSE T2 to discern normal and pathologic cases was evaluated., Results: Sixty patients were included. The overall diagnostic quality of the synthesized contrasts was non-inferior to conventional imaging scale (P=0.06). There was no significant difference in the legibility of normal and pathological anatomic structures of synthetized and conventional TSE T2 (all P>0.05) as well as for artifacts except for phase encoding (P=0.008). Inter-observer agreement was good to almost perfect (kappa between 0.66 and 1)., Conclusions: T2 synthesized contrasts, which also provides quantitative T2 information that could be useful, could be suggested as an equivalent technique in pediatric neuro-imaging, compared to conventional TSE T2., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Background The aim of this preliminary study is to evaluate the results of T1-weighted dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in pediatric patients at 1.5T, with a low peripheral intravenous gadoteric acid injection rate of 1 ml/s. Materials and methods Children with neurological symptoms were examined prospectively with conventional MRI and T1-weighted DCE MRI. An magnetic resonance perfusion analysis method was used to obtain time-concentration curves (persistent pattern, type-I; plateau pattern, type-II; washout pattern, type-III) and to calculate pharmacokinetic parameters. A total of two radiologists manually defined regions of interest (ROIs) in the part of the lesion exhibiting the greatest contrast enhancement and in the surrounding normal or contralateral tissue. Lesion/surrounding tissue or contralateral tissue pharmacokinetic parameter ratios were calculated. Tumors were categorized by grade (I-IV) using the World Health Organization (WHO) Grade. Mann-Whitney testing and receiver-operating characteristic (ROC) curves were performed. Results A total of nine boys and nine girls (mean age 10.5 years) were included. Lesions consisted of 10 brain tumors, 3 inflammatory lesions, 3 arteriovenous malformations and 2 strokes. We obtained analyzable concentration-time curves for all patients (6 type-I, 9 type-II, 3 type-III). K trans between tumor tissue and surrounding or contralateral tissue was significantly different ( p = 0.034). K trans ratios were significantly different between grade I tumors and grade IV tumors ( p = 0.027) and a K trans ratio value superior to 0.63 appeared to be discriminant to determine a grade IV of malignancy. Conclusions Our results confirm the feasibility of pediatric T1-weighted DCE MRI at 1.5T with a low injection rate, which could be of great value in differentiating brain tumor grades.

Objectives: Fetal MRI is a third intention examination to prenatal diagnosis. If its diagnostic value is well known in many pathologies, its place in the management of pregnancies remains unclear., Methods: We collected retrospectively demographical, radiological (fetal MRI indications, fetal anatomical region and diagnostic information provided by fetal MRI) and obstetrical data of pregnant patients in university prenatal center during a 5 years' period., Results: Among 2439 patients of the prenatal center, 196 (8%) patients with fetal MRI were included. The main anatomical regions studied were the brain (n=132, 67%), the thorax (n=31, 16%) and the abdomen (n=25, 13%). No cardiac fetal MRI was performed. Ninety-five percent of fetal MRI was consecutively of an ultrasound sign. Fetal brain MRI was abnormal in 65% of cases, the thoracic and abdominopelvic MRI in 81.5%. The ultrasound diagnosis was unchanged in 42%, completed in 50% and redirected in 8% of cases. A termination of pregnancy was deemed admissible in 31% of patients with MRI versus 21% in patients without MRI (P=0.001)., Conclusion: Fetal MRI requires selective indications and provides additional diagnostic information with important implications for the future of the pregnancy, particularly in case of severe and incurable pathologies. Our results could be useful as a reference basis for the comparison with others prenatal center practices., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Introduction: Neurofibromatosis type 1 (NF1) is frequently associated with hyperintense lesions on T2-weighted images called "unidentified bright objects" (UBO). To better characterize the functional significance of UBO, we investigate the basal ganglia and thalamus using spectroscopic imaging in children with NF1 and compare the results to anomalies observed on T2-weighted images., Methods: Magnetic resonance (MR) data of 25 children with NF1 were analyzed. On the basis of T2-weighted images analysis, two groups were identified: one with normal MR imaging (UBO- group; n = 10) and one with UBO (UBO+ group; n = 15). Within the UBO+ group, a subpopulation of patients (n = 5) only had lesions of the basal ganglia. We analyzed herein seven regions of interest (ROIs) for each side: caudate nucleus, capsulo-lenticular region, lateral and posterior thalamus, thalamus (lateral and posterior voxels combined), putamen, and striatum. For each ROI, a spectrum of the metabolites and their ratio was obtained., Results: Patients with abnormalities on T2-weighted images had significantly lower NAA/Cr, NAA/Cho, and NAA/mI ratios in the lateral right thalamus compared with patients with normal T2. These abnormal spectroscopic findings were not observed in capsulo-lenticular regions that had UBO but in the thalamus region that was devoid of UBO., Conclusion: Multivoxel spectroscopic imaging using short-time echo showed spectroscopic abnormalities in the right thalamus of NF1 patients harboring UBO, which were mainly located in the basal ganglia. This finding could reflect the anatomical and functional interactions of these regions.

Learning disabilities represent the main childhood complication in neurofibromatosis type 1 (NF1). Patients frequently exhibit T2-weighted hyperintensities called unidentified bright objects (UBOs) on brain magnetic resonance imaging (MRI), with unclear relationship to such cognitive disabilities. This study aimed to determine whether thalamo-striatal UBOs correlate with cognitive disturbances. Thirty-seven NF1 children were studied: 24 with UBOs (18 of which were thalamo-striatal UBOs), and 13 without UBOs. NF1 subjects carrying thalamo-striatal UBOs had significantly lower IQs and visuospatial performances than those without UBOs in this location. These results suggest that UBOs may contribute to NF1 cognitive impairments through thalamo-cortical dysfunction.

Malformations of cortical development are increasingly recognized as important causes of epilepsy, developmental delay and other neurological disorders. Our purpose is to present the relevance of the MRI in these pathologies with the clinical, genetic and therapeutic aspects. This classification is based on the three fundamental events of cortical formation: proliferation of neurons and glie in the periventricular zone, migration of postmitotic neurons to the periphery, subsequent cortical organization. MR analysis evaluates particularly the cortical thickness, sulcal and cortical morphology, gray-white matter junction, and looks for gray matter in abnormal location. These data coupled with the familial history, the seizure characteristics and genetic findings should allow an appropriate classification of the lesions. MR imaging allows the detection and classification of cortical malformations. MR imaging findings are primordial to consider surgery when the epilepsy becomes refractory to the anti-epileptic drugs. An adequate classification of these malformations should help to provide to the family an appropriate counseling both in terms of genetics and outcome.

Objective: During aortic coarctation follow-up, accurate diameter measurements using MRI are required. The purpose of this study was to compare the reproducibility of aortic measurements on axial and sagittal views using black blood (Fast-Spin-Echo) and three-dimensional Gadolinium-enhanced MR angiography., Subjects and Methods: We studied 34 patients who underwent evaluation after surgical treatment in the first year of life. The aortic measurements were made at six thoracic levels. We calculated the mean difference between the two sequences, and used Bland and Altman method and the comparison to zero., Results: With black blood, either on axial or sagittal views, aortic measurements were in agreement. Between two sequences, we considered as acceptable a mean difference of 0,5 mm with limits of agreement of +/- 3 mm. Difficulties were found for proximal ascending aorta measurements on all sequences. Using MR angiography, the highest agreement at the site of repair was on sagittal view, while the highest agreement at other sites was on axial views., Conclusion: Black blood sequence provides a better reproducibility for aortic measurements than native slices of MR angiography.

We studied the morphometric MRI findings and their correlation with cognitive functions in a population of 10 young adults shunted for congenital hydrocephalus related to spina bifida. Morphometric MRI analysis included measurement of the ventricular dilatation index, frontal and occipital parenchymal thickness and the size of the corpus callosum. The neuropsychological status was evaluated, notably to look for a discrepancy between verbal and performance skills, a finding which has previously been described in hydrocephalic children. We also investigated whether there was a correlation between cognitive function and cerebral morphometric indexes. In each case, MRI demonstrated the structural changes associated with the Chiari II malformation. The size of the lateral ventricles varied, ranging from important dilatation to small ventricles. Six patients had only partial development of the corpus callosum. All patients had a normal global IQ. In our population of young adults, we did not observe any discrepancy between verbal and visuospatial performances as has been described in children with hydrocephalus. We found no relationship between cognitive function and ventricle dilatation or parenchymal thickness or between the size of the corpus callosum and callosal transfer., (Copyright 2002 S. Karger AG, Basel)

The purpose of our study is to trace in vivo and during the perinatal period, the brain maturation process with exhaustive measures of the T2 relaxation time values. We also compared regional myelination progress with variations of the relaxation time values and of brain signal. T2 relaxation times were measured in 7 healthy premature newborns at the post-conceptional age of 37 weeks, using a Carr-Purcell-Meiboom-Gill sequence (echo time 60 to 150 ms), on a 2.35 Tesla Spectro-Imaging MR system. A total of 62 measures were defined for each subject within the brain stem, the basal ganglia and the hemispheric gray and white matter. The mean and standard deviation of the T2 values were calculated for each location. Regional T2 values changes and brain signal variations were studied. In comparison to the adult ones, the T2 relaxation time values of both gray and white matter were highly prolonged and a reversed ratio between gray and white matter was found. The maturational phenomena might be regionally correlated with a T2 value shortening. Significant T2 variations in the brainstem (p < 0.02), the mesencephalon (p < 0.05), the thalami (p < 0.01), the lentiform nuclei (p < 0.01) and the caudate nuclei (p < 0.02) were observed at an earlier time than they were visible on T2-weighted images. In the cerebral hemispheres, T2 values increased from the occipital white matter to parietal, temporal and frontal white matter (p < 0.05) and in the frontal and occipital areas from periventricular to subcortical white matter (p < 0.01). Maturational progress was earlier and better displayed with T2 measurements and T2 mapping. During the perinatal period, the measurements and analysis of T2 values revealed brain regional differences not discernible with T2-weighted images. It might be a more sensitive indicator for assessment of brain maturation.

Objectives: Assess three fat suppression sequences used to search for spinal metastases: TurboSTIR, phase contrast gradient-echo, and MISTEC-Chopper after gadolinium injection., Material and Methods: A prospective study was conducted in 10 patients with primary neoplasia. MIR sequences acquired (1 Tesla) were TurboSTIR, T1 spin-echo with and without gadolinium injection, phase contrast gradient-echo and M-Chop after gadolinium injection. Signal intensity in normal bone marrow, metastatic tissue, and subcutaneous fat as well as background noise was measured. Signal-to-noise (S/N) ratio was determined. Lesion borders, artefacts, and extent of detected lesions were determined quantitatively. Bone marrow signal intensity was also recorded., Results: S/N ratio was best with gradient-echo which identified well the borders of lesions within the hemopoietic marrow. For lesions located in high-fat marrow (as in post-radiation marrow), the high intensity signal of the lesion confounded with the fat signal. TurboSTIR gave effective fat signal suppression and was particularly useful for yellow marrow, less so for red marrow. This technique confounded cell proliferation with perilesional edema (enlarging lesion extention). In one case, this sequence did not detect a small lesion visible with the two other sequences. This sequence was sensitive to artefacts (especially vascular artefacts) which can produce false nodular images. M-Chop gave good suppression of vertebral fat tissue (better for yellow marrow) but subjective detection of lesions was more difficult., Conclusion: The phase contrast gradient-echo sequence after gadlinium injection appeared to be the best sequence excepting cases of post-trauma (radiotherapy or chemotherapy) fat transformation of the marrow where the TurboSTIR sequence could be preferred.

Objectif: Décrire une observation de spondylodiscite aiguë avec signes cliniques inhabituels chez un enfant. Observation: Un enfant de 3 ans a été hospitalisé pour des crises associant érection et douleurs abdominales survenant de façon pluriquotidienne le jour ou la nuit. L’enfant se plaignait depuis 4 semaines de douleurs lombaires d’installation progressive et accentuées lors de la marche. Il n’avait pas été noté de fièvre. L’examen clinique montrait une diminution des mobilités du rachis lombaire et une hyperlordose à la marche. Au bilan sanguin, la VS et le fibrinogène étaient élevés alors que la CRP et la Procalcitonine étaient normales. Les hémocultures étaient stériles. L’IRM rachidienne révélait une spondylodiscite L3-L4 avec abcès épidural postérieur fusant vers les foramens de L3. La ponction biopsie disco-vertébrale scano-guidée mettait en évidence un kingella kingae à la culture. L’évolution était favorable après antibiothérapie et immobilisation par un corset. Conclusion: La spondylodiscite de l’enfant est un diagnostic rare et difficile. Elle doit être suspectée devant toute douleur vertébrale de rythme inflammatoire, même en absence de fièvre et imposer la réalisation d’une IRM rachidienne Dans notre cas, la physiopathologie de l’érection n’est pas clairement établie. [ABSTRACT FROM AUTHOR]