Journal of neuroimaging : official journal of the American Society of Neuroimaging
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In this study, we used power analysis to calculate required sample sizes to detect group-level changes in quantitative neuroanatomical estimates derived from MRI scans obtained from multiple imaging centers. Sample size estimates were derived from (i) standardized 3T image acquisition protocols and (ii) nonstandardized clinically acquired images obtained at both 1.5 and 3T as part of the multicenter Human Epilepsy Project. Sample size estimates were compared to assess the benefit of standardizing acquisition protocols. ⋯ The use of standardized protocols yielded up to a five-fold reduction in required sample sizes to detect disease-related neuroanatomical changes, and is particularly beneficial for detecting subtle effects. Standardizing image acquisition protocols across scanners prior to commencing a study is a valuable approach to increase the statistical power of multicenter MRI 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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Cerebral vasodilatory capacity assessment for risk stratification in patients with extracranial arterial stenosis or occlusion may be useful. We describe a new method that assesses cerebral vasodilatory capacity as part of catheter-based cerebral angiography. ⋯ Selective vasodilatory response to intra-arterial nicardipine in the affected arterial distribution during catheter-based cerebral angiography may provide new data for risk stratification.
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The quantification of spinal cord (SC) atrophy by MRI has assumed an important role in assessment of neuroinflammatory/neurodegenerative diseases and traumatic SC injury. Recent technical advances make possible the quantification of gray matter (GM) and white matter tissues in clinical settings. However, the goal of a reliable diagnostic, prognostic or predictive marker is still elusive, in part due to large intersubject variability of SC areas. Here, we investigated the sources of this variability and explored effective strategies to reduce it. ⋯ The present work explored in a large cohort of healthy subjects the source of intersubject variability of SC areas and proposes effective normalization methods for its reduction.
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Ultrahigh-field 7T promises more than doubling the signal-to-noise ratio (SNR) of 3T for magnetic resonance imaging (MRI), particularly for MRI of magnetic susceptibility effects induced by B0 . Quantitative susceptibility mapping (QSM) is based on deconvolving the induced phase (or field) and would therefore benefit substantially from 7T. The purpose of this work was to compare QSM performance at 7T versus 3T in an intrascanner test-retest experiment with varying echo numbers (5 and 10 echoes). ⋯ Excellent image quality and good reproducibility was observed. 7T allows equivalent image quality of 3T in half of the scan time.