Water diffusion in rat brain in vivo as detected at very large b values is multicompartmental.

Details

Serval ID
serval:BIB_6AE9D64ED05B
Type
Article: article from journal or magazin.
Collection
Publications
Title
Water diffusion in rat brain in vivo as detected at very large b values is multicompartmental.
Journal
Magma
Author(s)
Pfeuffer J., Provencher S.W., Gruetter R.
ISSN
0968-5243 (Print)
ISSN-L
0968-5243
Publication state
Published
Issued date
1999
Volume
8
Number
2
Pages
98-108
Language
english
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, P.H.S.Publication Status: ppublish
Abstract
The diffusion-weighted signal attenuation of water in rat brain was measured with pulsed-field gradient nuclear magnetic resonance methods in a single voxel under in vivo and global ischemic conditions. The diffusion-attenuated water signal was observed in vivo at b values of 300 ms/microm2 (strength of diffusion weighting) and diffusion times up to 400 ms. A series of constant diffusion time (CT) experiments with varied gradient directions and diffusion times revealed a multiexponential decay with apparent diffusion coefficients (ADC) covering two orders of magnitude from 1 to 0.01 microm2/ms. In a four-exponential fit, the observed changes during global ischemia could be fully explained by changes in the relative volume fractions only with unchanged ADCs. An anisotropy of the ADC, detected at small b values, was not observed for the ADC at large b values, but for the concomitant volume fractions. An inverse Laplace Transform of the CT curves, performed with CONTIN, resulted in continuously distributed diffusion coefficients, for which the term 'diffusogram' is proposed. This approach was more appropriate than a discrete exponential model with four to six components, being related to the morphology of brain tissue and its cell size distribution. On the basis of an analytical, quantitative model, it is suggested that the measured ADC at small b values reflects mainly properties of the restricting boundaries, i.e. the relative volume fractions and the extracellular tortuosity, while the intrinsic intracellular diffusion constant and the exchange time are predicted to have minor influence.
Keywords
Animals, Anisotropy, Brain/metabolism, Brain/pathology, Brain Diseases/diagnosis, Brain Ischemia/metabolism, Diffusion, Magnetic Resonance Spectroscopy/methods, Male, Organophosphates/chemistry, Rats, Rats, Sprague-Dawley, Water/chemistry, Water/metabolism
Pubmed
Web of science
Create date
04/08/2010 15:28
Last modification date
20/08/2019 14:25
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