Search results for "diffusion MRI"
showing 10 items of 85 documents
Diffusion-weighted MRI of the lung with hyperpolarized helium-3: A study of reproducibility
2005
Purpose To determine the reproducibility of several parameters of the ADC measurement by calculating the scan-to-scan intrasubject variability. Materials and Methods Measurements were performed using a gradient-echo sequence with a bipolar gradient for diffusion weighting (b = 3.89 sec/cm2). Five patients with pulmonary emphysema, and six healthy-lung volunteers were included in the study. Images were acquired after inspiration of 3He during a single inspiratory breath-hold. To assess the reproducibility, the measurement was performed twice (time between measurements = 20 minutes) without repositioning the subjects. Analysis was performed on the basis of region-of-interest (ROI) analysis an…
Motor abnormalities and basal ganglia in first-episode psychosis (FEP)
2020
AbstractBackgroundMotor abnormalities (MAs) are the primary manifestations of schizophrenia. However, the extent to which MAs are related to alterations of subcortical structures remains understudied.MethodsWe aimed to investigate the associations of MAs and basal ganglia abnormalities in first-episode psychosis (FEP) and healthy controls. Magnetic resonance imaging was performed on 48 right-handed FEP and 23 age-, gender-, handedness-, and educational attainment-matched controls, to obtain basal ganglia shape analysis, diffusion tensor imaging techniques (fractional anisotropy and mean diffusivity), and relaxometry (R2*) to estimate iron load. A comprehensive motor battery was applied incl…
Metabolic and structural connectivity within the default mode network relates to working memory performance in young healthy adults.
2012
Abstract Studies of functional connectivity suggest that the default mode network (DMN) might be relevant for cognitive functions. Here, we examined metabolic and structural connectivity between major DMN nodes, the posterior cingulate (PCC) and medial prefrontal cortex (MPFC), in relation to normal working memory (WM). DMN was captured using independent component analysis of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) data from 35 young healthy adults (27.1 ± 5.1 years). Metabolic connectivity, a correlation between FDG uptake in PCC and MPFC, was examined in groups of subjects with (relative to median) low (n = 18) and high (n = 17) performance on digit span backward te…
Diffusion-tensor MR imaging at 1.5 and 3.0 T: initial observations.
2001
Diffusion-tensor MR imaging was compared at 1.5 and 3.0 T. With sufficient signal-to-noise ratio, we found no differences in fractional anisotropy. With a 40% higher signal-to-noise ratio at 3.0 T, higher resolution could be obtained without introduction of noise-related errors, albeit at the cost of increased geometric distortions caused by 3.0-T magnetic field inhomogeneities.
Solid bone tumors of the spine: Diagnostic performance of apparent diffusion coefficient measured using diffusion-weighted MRI using histology as a r…
2017
Purpose To assess the diagnostic performance of mean apparent diffusion coefficient (mADC) in differentiating benign from malignant bone spine tumors, using histology as a reference standard. Conventional magnetic resonance imaging (MRI) sequences have good reliability in evaluating spinal bone tumors, although some features of benign and malignant cancers may overlap, making the differential diagnosis challenging. Materials and Methods In all, 116 patients (62 males, 54 females; mean age 59.5 ± 14.1) with biopsy-proven spinal bone tumors were studied. Field strength/sequences: 1.5T MR system; T1-weighted turbo spin-echo (repetition time / echo time [TR/TE], 500/13 msec; number of excitatio…
Broad disruption of brain white matter microstructure and relationship with neuropsychological performance in male patients with severe alcohol depen…
2012
Aims In the last years, refined magnetic resonance diffusion tensor imaging (DTI) methods have become available to study microstructural alterations in the human brain. We investigated to what extent white matter tissue abnormalities are present in male patients after chronic, excessive alcohol consumption and if these alterations are correlated with measures of alcohol consumption and neuropsychological performance. Methods Twenty-four detoxified adult male patients with severe alcohol dependence and 23 healthy male control subjects were included in the study. Neuropsychological tests were assessed for executive function, attention, memory and visuospatial function. DTI was acquired and pr…
Disruption of White Matter Integrity in Bipolar Depression as a Possible Structural Marker of Illness
2011
Background: Diffusion tensor imaging allows the study of integrity of white matter (WM) tracts. Literature suggests that WM integrity could be altered in bipolar disorder. Heterogeneity of brain imaging methods, the studied samples, and drug treatments make localization, nature, and severity of the WM abnormalities unclear. Methods: We applied tract-based spatial statistics of diffusion tensor imaging measures to compare fractional anisotropy (FA), mean, and radial diffusivity of the WM skeleton in a group of 40 consecutively admitted inpatients affected by a major depressive episode without psychotic features with a diagnosis of bipolar disorder type I and 21 unrelated healthy volunteers f…
VBM-DTI correlates of verbal intelligence: a potential link to Broca's area.
2012
Abstract Human brain lesion studies first investigated the biological roots of cognitive functions including language in the late 1800s. Neuroimaging studies have reported correlation findings with general intelligence predominantly in fronto-parietal cortical areas. However, there is still little evidence about the relationship between verbal intelligence and structural properties of the brain. We predicted that verbal performance is related to language regions of Broca's and Wernicke's areas. Verbal intelligence quotient (vIQ) was assessed in 30 healthy young subjects. T1-weighted MRI and diffusion tensor imaging data sets were acquired. Voxel-wise regression analyses were used to correla…
Advanced magnetic resonance imaging of cortical laminar necrosis in patients with stroke
2019
Purpose The aim of this study was to assess the novel advanced magnetic resonance imaging findings of acute stage cortical laminar necrosis developing after complicated cardiovascular or abdominal surgery. Materials and methods This institutional review board-approved study included patients with postoperative stroke due to cortical laminar necrosis imaged with magnetic resonance in the acute stage. Brain magnetic resonance imaging examinations were obtained on a 3T magnetic resonance scanner within 48 hours of the neurological symptoms, including diffusion-weighted images (b value, 1000 s/mm2) and arterial spin labelling using a pseudo-continuous arterial spin labelling method in four pati…
Disturbed structural connectivity is related to inattention and impulsivity in adult attention deficit hyperactivity disorder
2010
Inattention and impulsivity are the most prominent clinical features of attention deficit hyperactivity disorder (ADHD) in adulthood. Structural and functional neuroimaging studies of subjects with ADHD have demonstrated abnormalities in several brain areas, including fronto-striatal and fronto-cerebellar networks. Mostly, these studies were based on volumetric measurements and have been conducted in children. We investigated white matter (WM) integrity and correlation with measures of attention and impulsivity in adult patients with ADHD adopting diffusion tensor imaging (DTI). N = 37 (21 males) never-medicated adult patients with ADHD combined subtype and N = 34 (16 males) healthy control…