Premium
Oscillating gradient measurements of water diffusion in normal and globally ischemic rat brain
Author(s) -
Does Mark D.,
Parsons Edward C.,
Gore John C.
Publication year - 2003
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.10385
Subject(s) - diffusion , nuclear magnetic resonance , effective diffusion coefficient , in vivo , ischemia , chemistry , waveform , physics , biophysics , materials science , magnetic resonance imaging , cardiology , medicine , thermodynamics , biology , voltage , microbiology and biotechnology , quantum mechanics , radiology
Abstract Oscillating gradients were used to probe the diffusion‐time/frequency dependence of water diffusion in the gray matter of normal and globally ischemic rat brain. In terms of a conventional definition of diffusion time, the oscillating gradient measurements provided the apparent diffusion coefficient (ADC) of water with diffusion times between 9.75 ms and 375 μs, an order of magnitude shorter than previously studied in vivo. Over this range, ADCs increased as much as 24% in vivo and 50% postmortem, depending on the nature of the oscillating gradient waveform used. Novel waveforms were employed to sample narrow frequency bands of the so‐called diffusion spectrum. This spectral description of ADC includes the effects of restriction and/or flow, and is independent of experimental parameters, such as diffusion time. The results in rat brain were found to be consistent with restricted diffusion and the known micro‐anatomy of gray matter. Differences between normal and postmortem data were consistent with an increase in water restriction and/or a decrease in flow, and tentatively suggest that physical changes following the onset of ischemia occur on a scale of about 2 μm, similar to a typical cellular dimension in gray matter. Magn Reson Med 49:206–215, 2003. © 2003 Wiley‐Liss, Inc.