Sökning: "magnetic diffusion"

Visar resultat 1 - 5 av 211 avhandlingar innehållade orden magnetic diffusion.

1. 1. Pushing diffusion MRI towards new dimensions

   Författare :Joao Martins; Fysikalisk kemi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NMR; MRI; diffusion; relaxation; multidimensional diffusion MRI; relaxation-diffusion correlations; Laplace NMR; porous media; tissue microstructure; heterogeneity; anisotropy;

   Sammanfattning : Diffusion-MRI techniques allow the non-invasive investigation of microstructural changes in living tissues. However, a detailed interpretation of the data is complicated by the fact that multiple microscopic environments with varying diffusion properties all contribute to the measured signal. LÄS MER

3. 2. Heterogeneous Materials - Diffusion, Laplace Spectrum, and Nuclear Magnetic Resonance

   Författare :Matias Nordin; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; eigenfunctions; eigenvalues; propagator; diffusion; Laplace operator; Nuclear Magnetic Resonance;

   Sammanfattning : In this thesis diffusion in heterogeneous materials is studied using spectral analysisof the Laplace operator. Relations to the effective diffusion constant and therelaxation rate of the time-dependent diffusion coefficient for porous systems arederived from the Laplace operator’s spectrum. LÄS MER

4. 3. Developing novel diffusion MRI methods for comprehensive analysis of restricted and anisotropic self-diffusion system

   Författare :Hong Jiang; Fysikalisk kemi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; MRI; diffusion; tissue microstructure; heterogeneity; diffusion encoding; q-vector; ;

   Sammanfattning : Diffusion MRI is a non-invasive imaging technique used to study the microstructural properties of biological tissues by observing the self-diffusion of water molecules. Traditional diffusion MRI methods, based on the pulsed gradient spin-echo sequence, employ magnetic field gradients to encode information about translational motion. LÄS MER

5. 4. Nuclear Magnetic Resonance for Diffusion Imaging Development and evaluation of spin-echo-based pulse sequences for in vivo studies of water self-diffusion

   Författare :Sara Brockstedt; Lund Medicinsk strålningsfysik; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; perfusion fraction; electrocardiographic triggering; segmented EPI SEPI ; echo-planar imaging EPI ; fast spin-echo FSE ; spin-echo SE ; navigator echoes; phase corrections; diffusion; Magnetic resonance; MRI; ischaemic stroke; Medicine human and vertebrates ; Medicin människa och djur ;

   Sammanfattning : The interest in diffusion imaging with nuclear magnetic resonance techniques has increased during the last few years. The main reason is the possibility of early diagnosis of acute ischaemic stroke, at a time when conventional MR techniques and computerised tomography fail. LÄS MER

7. 5. Investigation of Water Mobility using Diffusion-Sensitive MRI: The Role of q-Space Imaging, High b-Values and Diffusion Time

   Författare :Jimmy Lätt; Lund Medicinsk strålningsfysik; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MRI; kurtosis; high b-value; diffusion; diffusion time; NMR; q-space;

   Sammanfattning : Nuclear magnetic resonance (NMR) diffusometry provides important information about molecular motion on a microscopic scale. The advantage of NMR diffusometry is its ability to characterise microstructures non-invasively. This has made the method important not only in chemistry, biochemistry and materials science, but also in medicine. LÄS MER