title: Estimation of cell membrane permeability and intracellular diffusion coefficient of human gray matter.
abstract: The signal intensity of diffusion-weighted imaging (DWI) is sensitive to the intra- and extracellular diffusion coefficient of water and cell membrane permeability. We applied a method we proposed in previous papers to estimate noninvasively the membrane permeability and intracellular diffusion coefficient of normal human brain (gray matter) in 3 normal volunteers. We theoretically compared predicted signals and experiment results using a 1.5-tesla magnetic resonance (MR) imaging system. We acquired images using an echo planar imaging (EPI) sequence, applying motion-probing gradient (MPG) pulses in 3 directions. We periodically performed numerical simulations for various combinations of membrane permeability and intracellular diffusion coefficients using the finite-difference method. By minimizing the difference between signals obtained experimentally and those from numerical simulation, we could estimate membrane permeability (76+/-9 mm2/s mum) and intracellular diffusion coefficient (1.0+/-0.0 mm2/s) for the human brain. The estimated membrane permeability was the criterion value for diagnosing disease in gray matter.
authors.affiliation: Department of Radiology, University of Tokyo Hospital, Bunkyo-ku, Tokyo, Japan. imaet-rad@h.u-tokyo.ac.jp
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Imae
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shinohara
authors.forename: Masaki
authors.initials: M
authors.lastname: Sekino
authors.forename: Shoogo
authors.initials: S
authors.lastname: Ueno
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohsaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mima
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo