Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Exercise plays an important role in supporting overall brain health. However, the mechanisms by which exercise supports brain health are imprecisely defined. Further, brain hemodynamic changes during exercise are not clearly understood, especially in older adults. The primary aim of this study was to compare cerebral blood flow velocity and pulsatility index (PI) during moderate-intensity exercise between older adults with normal pulsatile flow (normal PI) and older adults with elevated pulsatile flow (elevated PI). Secondary aims were to compare cardiovascular disease risk and cognitive function between individuals with elevated and nonelevated PI. ⋯ The percent increase in PI from rest to moderate-intensity exercise was attenuated in the older adults with elevated resting PI. Higher resting PI may negatively affect brain health as evidenced by the slower processing speed scores.
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Acquiring and interpreting quantitative myelin-specific MRI data at an individual level is challenging because of technical difficulties and natural myelin variation in the population. To overcome these challenges, we used multiecho T2 myelin water imaging (MWI) to create T2 metric healthy population atlases that depict the mean and variation of myelin water fraction (MWF), and intra- and extracellular water mobility as described by geometric mean T2 (IEGMT2 ). ⋯ Our findings highlight the potential for using a quantitative T2 relaxation metric atlas to visualize and detect pathology in spinal cord. Our MWF and IEGMT2 atlases (URL: https://sourceforge.net/projects/mwi-spinal-cord-atlases/) can serve as normative references in the cervical spinal cord for other studies.
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Extracranial internal carotid artery stenoses (ICASs) may greatly differ with respect to morphological and hemodynamical aspects. The aim of this pilot study was to evaluate the use of multiparametric 3-dimensional (3D) contrast-enhanced ultrasound (3D-CEUS) to comprehensively examine ICAS. ⋯ In this pilot study, bedside multiparametric 3D-CEUS provided reliable estimations of different morphological and hemodynamical aspects of ICAS, thus ideally complementing CDS.
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Myelin water imaging (MWI) is a magnetic resonance imaging technique that quantifies myelin in-vivo. Although MWI has been extensively applied to study myelin-related diseases in groups, clinical use in individual patients is challenging mainly due to population heterogeneity. The purpose of this study was twofold: (1) create a normative brain myelin water atlas depicting the population mean and regional variability of myelin content; and (2) apply the myelin atlas to assess the degree of demyelination in individuals with multiple sclerosis (MS). ⋯ The myelin water atlas can be used as a reference (URL: https://sourceforge.net/projects/myelin-water-atlas/) to demonstrate areas of demyelination in individual MS participants. Future studies will expand the atlas age range, account for education, and other variables that may affect myelination.
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Hypoxic-ischemic injury (HII) is a major cause of neonatal death and neurodevelopmental disability. Head ultrasounds (HUS) in neonates with HII often show enhanced gray/white matter differentiation. We assessed the significance of this finding in predicting white matter structural integrity measured by diffusion tensor imaging (DTI) in neonates with HII. ⋯ Prehypothermia HUS WGR may predict posthypothermia white matter structural integrity and is potentially an early and easily obtainable biomarker of severity in neonatal HII.