How does water diffusion in human white matter change following ischemic stroke?

Hajime Tamura, Noriko Kurihara, Yoshio Machida, Akiko Nishino, Eku Shimosegawa

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

Purpose: Temporal evolution of the water apparent Diffusion coefficients (ADC) parallel (ADC||) and perpendicular (ADC⊥) to the human white matter tract following ischemia has not been investigated systematically. We attempted to quantify the evolution of ADC|| and ADC⊥ and examine whether it can be interpreted by a model of ischemic edema. Methods: We retrospectively selected 53 patients with ischemic lesions involving the posterior limb of the internal capsule (PLIC) and placed regions of interest in the right and left PLIC on ADC maps. We performed regression analysis of lesion-to-contralateral ratios of ADC|| and ADC⊥ against the time (t=1-1600 h) from onset. We then fitted the estimated time courses of ADC|| and ADC⊥ obtained from the analysis to a model of nerve tissue composed of cylinders (axons) and spheres corresponding to isotropic structures, particularly focal cytoplasmic swellings of glial cells and axons seen in ischemic white matter. Results: The evolution of ADC⊥ and ADC|| differed. The estimated time course of ADC|| in μm2·ms-1 was 0.64+0.88 exp (-0.24t) for 1 < t < 54 h and 0.00059t+0.61 for t ≥ 54 h (contralateral normal value, 1.52). That of ADC⊥ was 0.19-0.063 exp (-0.24t) for 1 < t < 54 h and 0.00040t+0.17 for t ≥ 54 h (normal value 0.22). The model fitted to these values showed that the volume of the cylinders decreased, that of the spheres increased, and extracellular volume changed little from one hour to approximately one day after stroke onset. Conclusion: In the human PLIC, ADC|| continued to decrease from one hour to a few days after stroke onset, and ADC⊥ tended to increase. The temporal evolution could be interpreted by progression of the focal cytoplasmic swelling of glial cells and axons previously observed in animal studies.

Original languageEnglish
Pages (from-to)121-134
Number of pages14
JournalMagnetic Resonance in Medical Sciences
Volume8
Issue number3
DOIs
Publication statusPublished - 2009

Keywords

  • Cytotoxic edema
  • Glia
  • Intracellular space
  • Vasogenic edema

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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