https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(14)61698-6.pdf

Global, regional, and national causes of child mortality in 2000-13, with projections to inform post-2015 priorities: an updated systematic analysis.

Mini Mental State

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Statistical Parametric Mapping The Analysis Of Functional Brain Images

生活習慣病とgenome-wide association study

MP2RAGE, a self bias-field corrected sequence for improved segmentation and T1-mapping at high field

Abstract Proton magnetic resonance spectroscopy is a non-invasive method of exploring cerebral metabolism. In Huntington’s disease, altered proton magnetic resonance spectroscopy-determined concentrations of several metabolites have been described; however, findings are often discrepant and longitudinal studies are lacking. Proton magnetic resonance spectroscopy metabolites may represent a source of biomarkers, thus their relationship with established markers of disease progression require further exploration to assess prognostic value and elucidate pathways associated with neurodegeneration. In a prospective single-site controlled cohort study with standardized collection of CSF, blood, phenotypic and volumetric imaging data, we used 3 T proton magnetic resonance spectroscopy in conjunction with the linear combination of model spectra method to quantify seven metabolites (total n-acetylaspartate, total creatine, total choline, myo-inositol, GABA, glutamate and glutathione) in the putamen of 59 participants at baseline (15 healthy controls, 15 premanifest and 29 manifest Huntington’s disease gene expansion carriers) and 48 participants at 2-year follow-up (12 healthy controls, 13 premanifest and 23 manifest Huntington’s disease gene expansion carriers). Intergroup differences in concentration and associations with CSF and plasma biomarkers; including neurofilament light chain and mutant Huntingtin, volumetric imaging markers; namely whole brain, caudate, grey matter and white matter volume, measures of disease progression and cognitive decline, were assessed cross-sectionally using generalized linear models and partial correlation. We report no significant groupwise differences in metabolite concentration at baseline but found total creatine and total n-acetylaspartate to be significantly reduced in manifest compared with premanifest participants at follow-up. Additionally, total creatine and myo-inositol displayed significant associations with reduced caudate volume across both time points in gene expansion carriers. Although relationships were observed between proton magnetic resonance spectroscopy metabolites and biofluid measures, these were not consistent across time points. To further assess prognostic value, we examined whether baseline proton magnetic resonance spectroscopy values, or rate of change, predicted subsequent change in established measures of disease progression. Several associations were found but were inconsistent across known indicators of disease progression. Finally, longitudinal mixed-effects models revealed glutamine + glutamate to display a slow linear decrease over time in gene expansion carriers. Altogether, our findings show some evidence of reduced total n-acetylaspartate and total creatine as the disease progresses and cross-sectional associations between select metabolites, namely total creatine and myo-inositol, and markers of disease progression, potentially highlighting the proposed roles of neuroinflammation and metabolic dysfunction in disease pathogenesis. However, the absence of consistent group differences, inconsistency between baseline and follow-up, and lack of clear longitudinal change suggests that proton magnetic resonance spectroscopy metabolites have limited potential as Huntington’s disease biomarkers.

https://academic.oup.com/braincomms/article-pdf/4/6/fcac258/47057057/fcac258.pdf

Longitudinal evaluation of proton magnetic resonance spectroscopy metabolites as biomarkers in Huntington’s disease

MR spectroscopy is an extremely valuable tool for assessing tissue biochemistry in vivo. Its use in the spinal cord presents several technical challenges due to geometrical, anatomical, and physiological constraints that have restricted its clinical application. With references to the limited literature available, issues relating to coil selection, patient immobilization, sequence choice, and placement of voxels of interest for single-voxel MRS studies in the spinal cord are discussed here. The importance of a reliable shimming routine is underlined, as well as cardiac gating. The selection of acquisition parameters is examined and postprocessing techniques are reviewed. Methods providing a quantitative estimation of metabolite concentrations are presented and potential pitfalls in interpretation discussed. Finally, suggestions are given to implement a robust protocol for single-voxel MRS in the cervical spinal cord.

Single Voxel MR Spectroscopy in the Spinal Cord: Technical Challenges and Clinical Applications

Arterial Spin Labeled Perfusion MRI for Assessing Antiangiogenic Therapy: A Step Forward or Just More Spin?

OBJECTIVE There is a pressing need to assess user-dependent reproducibility of multi-fibre probabilistic tractography in order to encourage clinical implementation of these advanced and relevant approaches. The goal of this study was to evaluate both intrinsic and inter-user reproducibility of corticospinal tract estimation. MATERIALS AND METHODS Six clinical datasets including motor functional and diffusion MRI were used. Three users performed an independent tractography analysis following identical instructions. Dice indices were calculated to quantify the reproducibility of seed region, fMRI-based end region, and streamline maps. RESULTS The inter-user reproducibility ranged 41-93%, 29-94%, and 50-92%, for seed regions, end regions, and streamline maps, respectively. Differences in streamline maps correlated with differences in seed and end regions. Good inter-user agreement in seed and end regions, yielded inter-user reproducibility close to the intrinsic reproducibility (92-97%) and in most cases higher than 80%. DISCUSSION Uncertainties related to user-dependent decisions and the probabilistic nature of the analysis should be considered when interpreting probabilistic tractography data. The standardization of the methods used to define seed and end regions is a necessary step to improve the accuracy and robustness of multi-fiber probabilistic tractography in a clinical setting. Clinical users should choose a feasible compromise between reproducibility and analysis duration.

/pdf/reproducibility-of-mri-based-white-matter-tract-estimation-1ey3tu3ro1.pdf

Reproducibility of MRI-based white matter tract estimation using multi-fiber probabilistic tractography: effect of user-defined parameters and regions.

<h3>Objectives</h3> Magnetic Resonance Imaging (MRI) can provide detailed information about the neonatal brain when it is rapidly developing and thus vulnerable to injuries. However, at standard MRI field strengths MRIs (1.5 and 3 Tesla (T)) there are limitations in tissue contrast and resolution. MRI imaging at ultra-high field (7T) provides significant gains in signal-to-noise-ratio and tissue contrast, which can markedly increase sensitivity to anatomy and pathology.<sup>1</sup> Experience of scanning neonates at 7T is limited and there are specific challenges due to differences in tissue composition and the ultra-high magnetic field environment. The aim of this study was to determine feasibility of 7T neonatal imaging and explore the potential gains in anatomical and pathological sensitivity. <h3>Methods</h3> 17 neonatal scans (median corrected age 40+3 weeks) were acquired with ethical approval (19/LO/1384) using a 7T Siemens MAGNETOM Terra system. Scanner software was modified to mitigate potential risks of temperature instability in neonates.<sup>2</sup> Infants were scanned in natural sleep following feeding, swaddled using a vacuum-evacuated bag and hearing protection with lateral immobilisation. Pulse-oximetry, heart rate and axillary temperature were continuously monitored by neonatal staff throughout scanning using 7T compatible equipment. 15 infants also had MRI scans on a 3T Philips Achieva system for comparison. Sequences acquired included high-resolution T2-weighted images in three orthogonal planes, susceptibility-weighted images, T1 and T2 quantitative maps, fMRI and spectroscopy. <h3>Results</h3> Images were successful acquired in 16 neonates (1 infant was imaged on 2 occasions) (table 1). All infants tolerated scanning on the 7T system and vital sign monitoring was stable throughout scanning over 52 minutes (range 25–80). There was no significant difference in temperature before and after 7T scanning (p-value=0.2). Additional detail of anatomical or pathological features were seen in 7T images compared to 3T, with image quality classified as equivalent or superior following neuroradiology review. These included improved visualization of the hippocampus, cerebellar vermis and occipital cortical folding. 7T images also provided improved visualization of cystic septi in periventricular leukomalacia and the haemorrhagic origin of cystic lesions in preterm infants. <h3>Conclusion</h3> We provide evidence for feasibility of 7T scanning in neonates and highlight the potential benefits for clinical care and research through improving image quality by increasing resolution and tissue contrast. In addition to improving diagnostic sensitivity, this could have provided new insight into the pathophysiological processes underlying poorly understood conditions such as neurodevelopmental disorders. <h3>References</h3> Yamada K, Yoshimura J, Watanabe M, Suzuki K. Application of 7 tesla magnetic resonance imaging for pediatric neurological disorders: early clinical experience. <i>Journal of Clinical Imaging Science</i> 2021;<b>11</b>:65. https://doi.org/10.25259/JCIS_185_2021 Malik Malik SJ, Hand JW, Satnarine R, Price AN, Hajnal JV. Specific absorption rate and temperature in neonate models resulting from exposure to a 7T head coil. <i>Magn Reson Med</i>. 2021;<b>86</b>:1299– 1313. https://doi.org/10.1002/mrm.28784 

Enrico De Vita

Papers

Longitudinal evaluation of proton magnetic resonance spectroscopy metabolites as biomarkers in Huntington’s disease

Single Voxel MR Spectroscopy in the Spinal Cord: Technical Challenges and Clinical Applications

Arterial Spin Labeled Perfusion MRI for Assessing Antiangiogenic Therapy: A Step Forward or Just More Spin?

Reproducibility of MRI-based white matter tract estimation using multi-fiber probabilistic tractography: effect of user-defined parameters and regions.

823 Ultra-high field 7 Tesla Magnetic Resonance Brain Imaging in Neonates: feasibility studies