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Biexponential diffusion attenuation in various states of brain tissue: Implications for diffusion‐weighted imaging
Author(s) -
Niendorf Thoralf,
Dijkhuizen Rick M.,
Norris David G.,
van Lookeren Campagne Menno,
Nicolay Klaas
Publication year - 1996
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.1910360607
Subject(s) - diffusion mri , attenuation , diffusion , nuclear magnetic resonance , diffusion imaging , magnetic resonance imaging , physics , medicine , radiology , optics , thermodynamics
Diffusion‐weighted single voxel experiments conducted at b ‐values up to 1 × 10 4 smm −2 yielded biexponential signal attenuation curves for both normal and ischemic brain. The relative fractions of the rapidly and slowly decaying components (f 1 , f 2 )are f 1 = 0.80 ± 0.02, f 2 = 0.17 ± 0.02 in healthy adult rat brain and f 1 = 0.90 ± 0.02, f 2 = 0.11 ± 0.01 in normal neonatal rat brain, whereas the corresponding values for the postmortem situation are f 1 = 0.69 ± 0.02, f 2 = 0.33 ± 0.02. It is demonstrated that the changes in f 1 and f 2 occur simultaneously to those in the extracellular and intracellular space fractions (f ex , f in ) during: (i) cell swelling after total circulatory arrest, and (ii) the recovery from N ‐methyl‐D‐aspartate induced excitotoxic brain edema evoked by MK‐801, as measured by changes in the electrical impedance. Possible reasons for the discrepancy between the estimated magnitude components and the physiological values are presented and evaluated. Implications of the biexponential signal attenuation curves for diffusion‐weighted imaging experiments are discussed.