Recent diffusion MRI studies of stroke in humans and animals have shown that the quantitative parameters characterising degree non-Gaussianity process are much more sensitive to ischemic changes than apparent coefficient (ADC) considered so far as "gold standard". The observed exceeded ADC by a remarkable factor 2 3. These were based on novel non-Gaussian methods, such kurtosis imaging (DKI) log-normal distribution function (LNDFI). As our previous work investigating animal model, combined...

In this work, we report a case study of stroke model in animals using two methods quantification the deviations from Gaussian behaviour: diffusion kurtosis imaging (DKI) and log‐normal distribution function (LNDFI). The affected regions were predominantly grey rather than white matter. parameter maps constructed for metrics quantifying apparent diffusivity (evaluated conventional tensor imaging, DKI LNDFI) those degree (mean σ characterising width distribution). We showed that both LNDFI...

Diffusion kurtosis imaging (DKI) is a promising extension of diffusion tensor imaging, giving new insights into the white matter microstructure and providing biomarkers. Given rapidly increasing number studies, DKI has potential to establish itself as valuable tool in brain diagnostics. However, become routine procedure, still needs be improved terms robustness, reliability, reproducibility. As it requires acquisitions at higher weightings, results are more affected by noise than imaging....

A NMR method is presented which permits one to probe order fluctuations in ordered materials such as nematics. Information on the parameter also accessible. The principle based standard stimulated-echo three-pulse sequence. Both stimulated and primary echo are recorded. quotient of amplitudes measured a function spacing first two rf pulses. attenuation curves corrected for spin-lattice relaxation show strong modulations directly reflecting material. This dipolar-correlation effect moreover...

To design a general framework for the optimization of an MRI protocol based on diffusion-weighted dual-echo steady-state (DW-DESS) sequence, enabling quantitative and simultaneous mapping proton density (PD), relaxation times T1 T2 diffusion coefficient D.A parameterization DW-DESS sequence minimizing Cramér-Rao lower bound each parameter estimate was proposed tested in phantom experiment. An extension implemented brain imaging to return rotationally invariant mean diffusivity (MD).In NiCl2...

Chain dynamics in a series of styrene-butadiene rubbers (SBR) was studied with the aid dipolar correlation effect (DCE) and field-cycling NMR relaxometry (FCR). The typical time scales two techniques are t>10−4 s t<10−3 s, respectively, therefore complementary. crosslink density polymer networks varied wide range. In order to prevent sinusoidal undulations stimulated-echo attenuation curves due spin exchange between groups different chemical-shift offsets, DCE samples examined...

Molecular dynamics of self-assembling triblock copolymers in a mixture with water was explored using nuclear magnetic resonance (NMR) diffusometry high-intensity field gradient pulses. With varying concentration, the diffusivities are found to cover 4 orders magnitude. The dramatic changes both rates and patterns polymer propagation can be attributed their ordering supermolecular formations prove sensitive means for probing structural dynamic features self-aggregation which only now, owing...

Chain dynamics in a series of natural rubbers with different cross-link densities was studied using the dipolar correlation effect (DCE) on stimulated echo. In dry samples, amplitudes echo were shown to be affected by attenuation mechanisms due DCE and spin exchange which occurs between protons CH CH3 (and/or CH2) groups polyisoprene chains. The estimated time 0.04 s. free undulations examined special modification radio frequency pulse sequence additional π-pulses inserted free-evolution...

The dipolar-correlation effect on the stimulated echo of nematics probes (a) order parameter and (b) distribution director fluctuations. This was employed for study orientational fluctuations in a nematic liquid crystal confined Bioran porous glasses with mean pore diameters 30, 70, 200 nm. No macroscopic preferential orientation could be detected material. reason is, that local is oriented by surface interactions rather than magnetic field. As already shown our previous work, attenuation...

Molecular dynamics of triblock copolymers under confinement by the nanochannels SBA-15 was investigated using pulsed field gradient (PFG) NMR spectroscopy with high-intensity pulses. The mesoporous material synthesized surfactant Pluronic P123 (EO20-PO70-EO20). diffusion in mixtures water studied both bulk and condition channels SBA-15. As a result, at room temperature is more than factor three smaller that same polymer mixture water. A pronounced atypical dependence measured diffusivities...

Abstract We present a novel NMR approach to the determination of crosslink densities in rubber materials. The method is based on dipolar correlation effect (DCE) stimulated echo examined series samples and linear polyisoprene. parameter evaluated from attenuation curves mean‐squared fluctuation associated with anisotropic reorientations macromolecular backbones. contributions DCE constraints due excluded volume effects chemical crosslinks are estimated. A strong dependence density combined...

Glutamate is the major excitatory neurotransmitter in human brain and has a central role both intrinsic stimulus-induced activity. We conducted study cohort of healthy, male volunteers which glutamate levels were measured posterior cingulate cortex (PCC) using 1H magnetic resonance spectroscopy at 3T. The advantages simultaneous electroencephalography imaging (EEG-MRI) exploited subjects same session under physiological conditions. Diffusion tensor (DTI), functional MRI (fMRI) EEG order to...

Order fluctuations in polydiethylsiloxane (PDES) mesophase are studied using the dipolar-correlation effect on stimulated echo. The attenuation of echo is described basis a two-site slow exchange model. conclusion that collective chain result temporarily and locally ordered defect-enriched states. local order parameter inhomogeneously distributed samples as indicated by absence any oscillatory modulation effect. mean time between two mobility states varies temperature range 0.1 1 s. It...