Microstructural changes in ischemic cortical gray matter predicted by a model of diffusion-weighted MRI

@article{citeulike:1606700, abstract = {To understand the diffusion attenuated MR signal from normal and ischemic brain tissue in order to extract structural and physiological information using mathematical modeling, taking into account the transverse relaxation rates in gray matter.We fit our diffusion model to the diffusion-weighted MR signal obtained from cortical gray matter in healthy subjects. Our model includes variable volume fractions, intracellular restriction effects, and exchange between compartments in addition to individual diffusion coefficients and transverse relaxation rates for each compartment. A global optimum was found from a wide range of parameter permutations using cluster computing. We also present simulations of cell swelling and changes of exchange rate and intracellular diffusion as possible cellular mechanisms in ischemia.Our model estimates an extracellular volume fraction of 0.19 in accordance with the accepted value from histology. The absolute apparent diffusion coefficient obtained from the model was similar to that of experiments. The model and the experimental results indicate significant differences in diffusion and transverse relaxation between the tissue compartments and slow water exchange. Our model reproduces the signal changes observed in ischemia via physiologically credible mechanisms.Our modeling suggests that transverse relaxation has a profound influence on the diffusion attenuated MR signal. Our simulations indicate cell swelling as the primary cause of the diffusion changes seen in the acute phase of brain ischemia. J. Magn. Reson. Imaging 2007. {\copyright} 2007 Wiley-Liss, Inc.}, address = {Center of Functionally Integrative Neuroscience/Department of Neuroradiology, Aarhus University Hospital, Aarhus University, Aarhus, Denmark; Institute of Physics and Astronomy, Aarhus University, Aarhus, Denmark}, author = {Vestergaard-Poulsen, Peter and Hansen, Brian and Østergaard, Leif and Jakobsen, Rikke }, citeulike-article-id = {1606700}, doi = {10.1002/jmri.21030}, journal = {Journal of Magnetic Resonance Imaging}, keywords = {brain, diffusion, dw-mri, model, mri}, number = {3}, pages = {529--540}, posted-at = {2007-08-30 07:37:50}, priority = {4}, title = {Microstructural changes in ischemic cortical gray matter predicted by a model of diffusion-weighted MRI}, url = {http://dx.doi.org/10.1002/jmri.21030}, volume = {26}, year = {2007} }

TY - JOUR ID - citeulike:1606700 L3 - citeulike-article-id:1606700 TI - Microstructural changes in ischemic cortical gray matter predicted by a model of diffusion-weighted MRI JF - Journal of Magnetic Resonance Imaging VL - 26 IS - 3 SP - 529 EP - 540 AD - Center of Functionally Integrative Neuroscience/Department of Neuroradiology, Aarhus University Hospital, Aarhus University, Aarhus, Denmark; Institute of Physics and Astronomy, Aarhus University, Aarhus, Denmark N2 - To understand the diffusion attenuated MR signal from normal and ischemic brain tissue in order to extract structural and physiological information using mathematical modeling, taking into account the transverse relaxation rates in gray matter.We fit our diffusion model to the diffusion-weighted MR signal obtained from cortical gray matter in healthy subjects. Our model includes variable volume fractions, intracellular restriction effects, and exchange between compartments in addition to individual diffusion coefficients and transverse relaxation rates for each compartment. A global optimum was found from a wide range of parameter permutations using cluster computing. We also present simulations of cell swelling and changes of exchange rate and intracellular diffusion as possible cellular mechanisms in ischemia.Our model estimates an extracellular volume fraction of 0.19 in accordance with the accepted value from histology. The absolute apparent diffusion coefficient obtained from the model was similar to that of experiments. The model and the experimental results indicate significant differences in diffusion and transverse relaxation between the tissue compartments and slow water exchange. Our model reproduces the signal changes observed in ischemia via physiologically credible mechanisms.Our modeling suggests that transverse relaxation has a profound influence on the diffusion attenuated MR signal. Our simulations indicate cell swelling as the primary cause of the diffusion changes seen in the acute phase of brain ischemia. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc. KW - brain KW - diffusion KW - dw-mri KW - model KW - mri AU - Vestergaard-Poulsen, Peter AU - Hansen, Brian AU - Østergaard, Leif AU - Jakobsen, Rikke PY - 2007/// UR - http://dx.doi.org/10.1002/jmri.21030 ER -