Search results for "Diffusion"
showing 10 items of 1615 documents
Functional implications of hippocampal volume and diffusivity in mild cognitive impairment.
2005
Abstract Hippocampal atrophy has been related to mild cognitive impairment (MCI) and early Alzheimer disease (AD), but the diagnostic significance of cross-sectionally determined hippocampal volumes is still ambiguous. Diffusion-Tensor-Imaging (DTI) in MCI patients revealed an association of microstructural changes in hippocampal areas with verbal memory decline. MRI volumetry and DTI were combined to investigate 18 MCI patients attending a memory clinic, and 18 carefully age- and gender-matched healthy controls. Neuropsychological testing, high resolution T1-weighted volume MRI scans, and DTI scans with regions-of-interest in hippocampal areas were applied. Left hippocampal volume was sign…
Functional Evaluation of Emphysema Using Diffusion-Weighted 3Helium-Magnetic Resonance Imaging, High-Resolution Computed Tomography, and Lung Functio…
2004
Purpose: To assess the emphysematous enlargement of distal air-spaces and concomitant large and small airway disease using diffusion-weighted 3 Helium-magnetic resonance imaging (MRI), high-resolution computed tomography (HRCT), and lung function tests (LFT). Methods: Seven patients were examined after single lung transplantation (LTx) and 1 before double LTx for various forms of emphysema. Five patients after double LTx served as controls. Patients were assessed by 3 Helium-MRI (apparent diffusion coefficient [ADC]), HRCT (mean lung density [MLD], emphysema index [El]), and LFT. Results: Transplanted lungs: mean ADC = 0.17 cm 2 /s, MLD = -848 H, El = 22%. Emphysematous lungs: mean ADC = 0.…
Predicting conversion to dementia in mild cognitive impairment by volumetric and diffusivity measurements of the hippocampus.
2005
In our prospective study of diffusion tensor imaging (DTI), we measured hippocampal mean diffusivity (MD) and volumes in amnestic mild cognitive impairment (MCI). Thirteen MCI patients were followed-up by clinical assessment over a mean 112-year period. MCI patients who converted to dementia (6 of 13) during the observation period had slightly elevated left hippocampal mean diffusivity at baseline compared with MCI patients who remained clinically stable. Hippocampal volumes as well as baseline verbal memory and MMSE did not differ significantly between stable MCI patients and converters. Hippocampal diffusivity was superior to hippocampal volumes for prediction of conversion to dementia in…
MRI patient selection for endovascular thrombectomy in acute ischemic stroke: correlation between pretreatment diffusion weighted imaging and outcome…
2018
Introduction: Eligibility for endovascular treatment (EVT) in patients with acute ischemic stroke (AIS) depends, amongst other factors, on CT- or MR-based scores. The aim of this study was to investigate the role of Alberta Stroke Program Early CT score based on diffusion weighted imaging (MR-ASPECT) in the assessment of brain damage pre-EVT, patient selection for EVT and outcome. Materials and methods: We included in this study patients with National Institute of Health stroke score (NIHSS) at admission ≥ 8, MR-ASPECT ≥ 5 and anterior AIS, who were treated with EVT in our hospital. All patients were clinically evaluated at admission, post-EVT, discharge and at 3-month follow-up. We used MR…
Assessment of brain core temperature using MR DWI-thermometry in Alzheimer disease patients compared to healthy subjects
2017
Purpose: To assess the brain core temperature of Alzheimer disease (AD) patients in comparison with healthy volunteers using diffusion-weighted thermometry. Materials and methods: Fourteen AD patients (3 men, 11 women; age range 60–81 years, mean age 73.8 ± 6.1 years) and 14 healthy volunteers, age and sex-matched (mean age 70.1 ± 6.9 years; range 62–84 years; 5 men, 9 women) underwent MR examination between February 2014 and March 2016. MR imaging studies were performed with a 1.5-T MR scanner. Brain core temperature (T: °C) was calculated using the following equation from the diffusion coefficient (D) in the lateral ventricular (LV) cerebrospinal fluid: T = 2256.74/ln (4.39221/D) − 273.15…
PI-RADS 3 Lesions: Role of Prostate MRI Texture Analysis in the Identification of Prostate Cancer
2021
Abstract Purpose To determine the diagnostic performance of texture analysis of prostate MRI for the diagnosis of prostate cancer among Prostate Imaging Reporting and Data System (PI-RADS) 3 lesions. Materials and Methods Forty-three patients with at least 1 PI-RADS 3 lesion on prostate MRI performed between June 2016 and January 2019 were retrospectively included. Reference standard was pathological analysis of radical prostatectomy specimens or MRI-targeted biopsies. Texture analysis extraction of target lesions was performed on axial T2-weighted images and apparent diffusion coefficient (ADC) maps using a radiomic software. Lesions were categorized as prostate cancer (Gleason score [GS] …
Linking Microstructural Integrity and Motor Cortex Excitability in Multiple Sclerosis
2021
Motor skills are frequently impaired in multiple sclerosis (MS) patients following grey and white matter damage with cortical excitability abnormalities. We applied advanced diffusion imaging with 3T magnetic resonance tomography for neurite orientation dispersion and density imaging (NODDI), as well as diffusion tensor imaging (DTI) in 50 MS patients and 49 age-matched healthy controls to quantify microstructural integrity of the motor system. To assess excitability, we determined resting motor thresholds using non-invasive transcranial magnetic stimulation. As measures of cognitive-motor performance, we conducted neuropsychological assessments including the Nine-Hole Peg Test, Trail Makin…
Physical activity, aerobic fitness, and brain white matter : Their role for executive functions in adolescence
2020
Highlights • Aerobic fitness level, but not physical activity, is related to white matter properties in the brain. • The relation between physical activity and working memory is moderated by fractional anisotropy (FA) of the corpus callosum. • The FA of the corpus callosum and superior corona radiata moderates the relation between aerobic fitness and working memory.
The Diffusion of Price-Related Word-of-Mouth: A Study Exploring the Role of Market Mavens and Social Ties
2020
This study sheds light on the process of price-related word-of-mouth by exploring the dissemination of positively and negatively valanced price information as well as the role of social ties and ma...
Mobile Application Diffusion and Success: An Interpretative Approach to Influential Factors
2018
The rapid evolution of mobile computing technology has been attributed to the increasing capitalizing by companies on this innovative business medium. The result of conformity between technology advancement and market demand increment for mobility has led to the development of different categories of mobile businesses in recent years. This research reviews the previous related literature to the subject and by deploying meta-synthesis as a systematic quantitative method; a generic model covering important factors contributing to mobile application diffusion is presented. The proposed comprehensive model consists of users' specifications, technical aspects and contextual factors in the first …