Biexponential diffusion attenuation in the rat spinal cord: Computer simulations based on anatomic images of axonal architecture

Chih Liang Chin, Felix W. Wehrli, Scott N. Hwang, Masaya Takahashi, David B. Hackney

Research output: Contribution to journalArticlepeer-review

80 Scopus citations


Water diffusion in neurological tissues is known to possess multicomponent diffusion behavior. The fractions of fast and slow apparent diffusion components have often been attributed to the volume fractions of extracellular space (ECS) and intracellular space (ICS) although diffusion fractions are at variance with the tissue compartment volume ratios. In this article this puzzle was examined with a finite difference diffusion simulation model on the basis of optical images from sectioned rat spinal cord. Here the results show that assignment of fractions obtained from biexponential fits of fast and slow diffusion attenuation to ECS and ICS volume ratios is not correct. Rather, the observed multicomponent diffusion behavior is caused by motional restriction and limited intercompartmental water exchange in that at long diffusion times diffusion attenuation is shown to become monoexponential. Although the measured apparent diffusion fractions also depend on T2 relaxation time of water protons in the various compartments, the sensitivity to T2 is small and thus T2 differences are unlikely to explain the mismatch between apparent diffusion fractions and cellular volume fractions.

Original languageEnglish (US)
Pages (from-to)455-460
Number of pages6
JournalMagnetic Resonance in Medicine
Issue number3
StatePublished - 2002

All Science Journal Classification (ASJC) codes

  • Radiology Nuclear Medicine and imaging

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