Transient increase of fractional anisotropy in reversible vasogenic edema

J Cereb Blood Flow Metab. 2016 Oct;36(10):1731-1743. doi: 10.1177/0271678X16630556. Epub 2016 Feb 10.

Abstract

Brain vasogenic edema, involving disruption of the blood-brain barrier, is a common pathological condition in several neurological diseases, with a heterogeneous prognosis. It is sometimes reversible, as in posterior reversible encephalopathy syndrome, but often irreversible and our current clinical tools are insufficient to reveal its reversibility. Here, we show that increased fractional anisotropy in magnetic resonance imaging is associated with the reversibility of vasogenic edema. Spontaneously, hypertensive rats-stroke prone demonstrated posterior reversible encephalopathy syndrome-like acute encephalopathy in response to high-dose cyclosporine A treatment; the deteriorating neurological symptoms and worsening scores in behavioral tests, which were seen in acute phase, dissappered after recovery by cessation of cyclosporine A. In the acute phase of encephalopathy, the fractional anisotropy and apparent diffusion coefficient increased in areas with IgG leakage. This increase of fractional anisotropy occurred in the absence of demyelination: fluid leakage into the myelinated space increased the axial, but not the radial, diffusivity, resulting in the increased fractional anisotropy. This increased fractional anisotropy returned to pre-encephalopathy values in the recovery phase. Our results highlight the importance of the fractional anisotropy increase as a marker for the reversibility of brain edema, which can delineate the brain areas for which recovery is possible.

Keywords: Blood-brain barrier; brain vasogenic edema; diffusion tensor imaging; fractional anisotropy; posterior reversible encephalopathy syndrome.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anisotropy
  • Behavior, Animal / drug effects
  • Blood-Brain Barrier / diagnostic imaging
  • Brain Edema / chemically induced
  • Brain Edema / diagnostic imaging*
  • Brain Edema / pathology
  • Cyclosporine / administration & dosage
  • Cyclosporine / toxicity
  • Diffusion Tensor Imaging / methods*
  • Disease Models, Animal
  • Immunoglobulin G / metabolism
  • Magnetic Resonance Imaging / methods*
  • Posterior Leukoencephalopathy Syndrome / chemically induced
  • Posterior Leukoencephalopathy Syndrome / diagnostic imaging*
  • Posterior Leukoencephalopathy Syndrome / pathology
  • Rats, Inbred SHR

Substances

  • Immunoglobulin G
  • Cyclosporine