Literature is scarce regarding volumetric measures of limbic system components across the pediatric age range. The purpose of this study is to remedy this scarcity by reporting continuous volumetric ...measurements of limbic system components, and to provide consistent stratification data including age-related trajectories and sex-related differences in the pediatric age range in order to improve the recognition of structural variations that might reflect pathology.
In this retrospective study, MRI sequences of children with normal clinical MRI examinations of the brain acquired between January 2010 and December 2019 were included. Isotropic 3D T1-weighted were processed using FreeSurfer version 7.3. Total brain volume and volumes of the limbic system including the hippocampus, parahippocampal gyrus, amygdala, hypothalamus, cingulate gyrus, entorhinal cortex, anteroventral thalamic nucleus, and whole thalamus were assessed. Parcellated output was displayed with the respective label map overlay and images were visually inspected for accuracy of regional segmentation results. Continuous data are provided as mean and standard deviation with quadratic trendlines and as mean and 95% confidence intervals. Categorical data are presented as integers and percentages (%).
A total of 724 children (401 female, 55.4%), with a mean age at time of MRI of 10.9 ± 4.2 years (range: 1.9-18.2 years), were included in the study. For females, the total brain volume increased from 955 ± 70 mL at the age of 2-3 years to 1140 ± 110 mL at the age of 17-18 years. Similarly, the total brain volume increased for males from 1004 ± 83 mL to 1263 ± 96 mL. The maximum volume was noted at 11-12 years for females (1188 ± 90 mL) and at 14-15 years for males (1310 ± 159 mL). Limbic system structures reached their peak volume more commonly between the 13-14 years to 17-18 years age groups. The male cingulate gyrus, entorhinal cortex, and anteroventral thalamic nucleus reached peak volume before or at 9-10 years.
This study provides unique age- and sex-specific volumes of the components of the limbic system throughout the pediatric age range to serve as normal values in comparative studies. Quantification of volumetric abnormalities of the limbic system on brain MRI may offer insights into phenotypical variations of diseases and may help elucidate new pathological phenotypes.
Objective
Despite the routine use of antenatal steroids, exogenous surfactants, and different noninvasive ventilation methods, many extremely low gestational age neonates, preterm, and term infants ...eventually require invasive ventilation. In addition to prematurity, mechanical ventilation itself can induce ventilator‐induced lung injury leading to lifelong pulmonary sequelae. Besides conventional mechanical ventilation, high‐frequency oscillatory ventilation (HFOV) with tidal volumes below dead space and high ventilation frequencies is used either as a primary or rescue therapy in severe neonatal respiratory failure.
Methods and Results
Applying a high‐resolution computational lung modeling technique in a preterm infant, we studied three different high‐frequency ventilation settings as well as conventional ventilation (CV) settings. Evaluating the computed oxygen delivery (OD) and lung mechanics (LM) we outline for the first time how changing ventilator settings from CV to HFOV lead to significant improvements in OD and LM.
Conclusion
This personalized “digital twin” strategy advances our general knowledge of protective ventilation strategies in neonatal care and can support decisions on various modes of ventilatory therapy at high frequencies.
Abstract
Background
Systemic infiltration of the brain by tumor cells is a hallmark of glioma pathogenesis which may cause disturbances in functional connectivity. We hypothesized that aggressive ...high-grade tumors cause more damage to functional connectivity than low-grade tumors.
Methods
We designed an imaging tool based on resting-state functional (f)MRI to individually quantify abnormality of functional connectivity and tested it in a prospective cohort of patients with newly diagnosed glioma.
Results
Thirty-four patients were analyzed (World Health Organization WHO grade II, n = 13; grade III, n = 6; grade IV, n = 15; mean age, 48.7 y). Connectivity abnormality could be observed not only in the lesioned brain area but also in the contralateral hemisphere with a close correlation between connectivity abnormality and aggressiveness of the tumor as indicated by WHO grade. Isocitrate dehydrogenase 1 (IDH1) mutation status was also associated with abnormal connectivity, with more alterations in IDH1 wildtype tumors independent of tumor size. Finally, deficits in neuropsychological performance were correlated with connectivity abnormality.
Conclusion
Here, we suggested an individually applicable resting-state fMRI marker in glioma patients. Analysis of the functional connectome using this marker revealed that abnormalities of functional connectivity could be detected not only adjacent to the visible lesion but also in distant brain tissue, even in the contralesional hemisphere. These changes were associated with tumor biology and cognitive function. The ability of our novel method to capture tumor effects in nonlesional brain suggests a potential clinical value for both individualizing and monitoring glioma therapy.
Agenesis of the corpus callosum (ACC) is among the most frequent human brain malformations with an incidence of 0.5-70 in 10,000. It is a heterogeneous condition, for which several different genetic ...causes are known, for example, ACC as part of monogenic syndromes or complex chromosomal rearrangements. We systematically evaluated the data of 172 patients with documented corpus callosum abnormalities in the records, and 23 patients with chromosomal rearrangements known to be associated with corpus callosum changes. All available neuroimaging data, including CT and MRI, were re-evaluated following a standardized protocol. Whenever feasible chromosome and subtelomere analyses as well as molecular genetic testing were performed in patients with disorders of the corpus callosum in order to identify a genetic diagnosis. Our results showed that 41 patients with complete absence (agenesis of the corpus callosum-ACC) or partial absence (dysgenesis of the corpus callosum-DCC) were identified. Out of these 28 had ACC, 13 had DCC. In 11 of the 28 patients with ACC, the following diagnoses could be established: Mowat-Wilson syndrome (n = 2), Walker-Warburg syndrome (n = 1), oro-facial-digital syndrome type 1 (n = 1), and chromosomal rearrangements (n = 7), including a patient with an apparently balanced reciprocal translocation, which led to the disruption and a predicted loss of function in the FOXG1B gene. The cause of the ACC in 17 patients remained unclear. In 2 of the 13 patients with DCC, unbalanced chromosomal rearrangements could be detected (n = 2), while the cause of DCC in 11 patients remained unclear. In our series of cases a variety of genetic causes of disorders of the corpus callosum were identified with cytogenetic anomalies representing the most common underlying etiology.
Introduction
Microstructural alterations as assessed by diffusion tensor imaging (DTI) are key findings in both Alzheimer's disease (AD) and small vessel disease (SVD). We determined the contribution ...of each of these conditions to diffusion alterations.
Methods
We studied six samples (N = 365 participants) covering the spectrum of AD and SVD, including genetically defined samples. We calculated diffusion measures from DTI and free water imaging. Simple linear, multivariable random forest, and voxel‐based regressions were used to evaluate associations between AD biomarkers (amyloid beta, tau), SVD imaging markers, and diffusion measures.
Results
SVD markers were strongly associated with diffusion measures and showed a higher contribution than AD biomarkers in multivariable analysis across all memory clinic samples. Voxel‐wise analyses between tau and diffusion measures were not significant.
Discussion
In memory clinic patients, the effect of SVD on diffusion alterations largely exceeds the effect of AD, supporting the value of diffusion measures as markers of SVD.
The hippocampus and its subfields (HippSub) are reported to be diminished in patients with Alzheimer's disease (AD), bipolar disorder (BD), and major depressive disorder (MDD). We examined these ...groups vs healthy controls (HC) to reveal HippSub alterations between diseases.
We segmented 3T-MRI T2-weighted hippocampal images of 67 HC, 58 BD, and MDD patients from the AFFDIS study and 137 patients from the DELCODE study assessing cognitive decline, including subjective cognitive decline (SCD), amnestic mild cognitive impairment (aMCI), and AD, via Free Surfer 6.0 to compare volumes across groups.
Groups differed significantly in several HippSub volumes, particularly between patients with AD and mood disorders. In comparison to HC, significant lower volumes appear in aMCI and AD groups in specific subfields. Smaller volumes in the left presubiculum are detected in aMCI and AD patients, differing from the BD group. A significant linear regression is seen between left hippocampus volume and duration since the first depressive episode.
HippSub volume alterations were observed in AD, but not in early-onset MDD and BD, reinforcing the notion of different neural mechanisms in hippocampal degeneration. Moreover, duration since the first depressive episode was a relevant factor explaining the lower left hippocampal volumes present in groups.
Objectives
To assess the effect of the COVID-19 pandemic on the proportion of abnormal paediatric neuroimaging findings as a surrogate marker for potential underutilisation.
Methods
Consecutive ...paediatric brain MRIs performed between March 27th and June 19th 2019 (Tbaseline) and March 23rd and June 1st 2020 (Tpandemic) were reviewed and classified according to presence or absence and type of imaging abnormality, and graded regarding severity on a 5-point Likert scale, where grade 4 was defined as abnormal finding requiring non-urgent intervention and grade 5 was defined as acute illness prompting urgent medical intervention. Non-parametric statistical testing was used to assess for significant differences between Tpandemic vs. Tbaseline.
Results
Fewer paediatric MRI brains were performed during Tpandemic compared to Tbaseline (12.2 vs 14.7 examinations/day). No significant difference was found between the two time periods regarding sex and age (Tbaseline: 557 females (44.63%), 7.95 ± 5.49 years, Tpandemic: 385 females (44.61%), 7.64 ± 6.11 years; p = 1 and p = .079, respectively). MRI brain examinations during Tpandemic had a higher likelihood of being abnormal, 41.25% vs. 25.32% (p<.0001). Vascular abnormalities were more frequent during Tpandemic (11.01% vs 8.01%, p = .02), congenital malformations were less common (8.34% vs 12.34%, p = .004). Severity of MRI brain examinations was significantly different when comparing group 4 and group 5 individually and combined between Tbaseline and Tpandemic (p = .0018, p < .0001, and p <.0001, respectively).
Conclusions
The rate of abnormality and severity found on paediatric brain MRI was significantly higher during the early phase of the pandemic, likely due to underutilisation.
PDF
