Elevated brain oxygen extraction fraction measured by MRI susceptibility relates to perfusion status in acute ischemic stroke

J Cereb Blood Flow Metab. 2020 Mar;40(3):539-551. doi: 10.1177/0271678X19827944. Epub 2019 Feb 7.

Abstract

Recent clinical trials of new revascularization therapies in acute ischemic stroke have highlighted the importance of physiological imaging to identify optimal treatments for patients. Oxygen extraction fraction (OEF) is a hallmark of at-risk tissue in stroke, and can be quantified from the susceptibility effect of deoxyhemoglobin molecules in venous blood on MRI phase scans. We measured OEF within cerebral veins using advanced quantitative susceptibility mapping (QSM) MRI reconstructions in 20 acute stroke patients. Absolute OEF was elevated in the affected (29.3 ± 3.4%) versus the contralateral hemisphere (25.5 ± 3.1%) of patients with large diffusion-perfusion lesion mismatch (P = 0.032). In these patients, OEF negatively correlated with relative CBF measured by dynamic susceptibility contrast MRI (P = 0.004), suggesting compensation for reduced flow. Patients with perfusion-diffusion match or no hypo-perfusion showed less OEF difference between hemispheres. Nine patients received longitudinal assessment and showed OEF ratio (affected to contralateral) of 1.2 ± 0.1 at baseline that normalized (decreased) to 1.0 ± 0.1 at follow-up three days later (P = 0.03). Our feasibility study demonstrates that QSM MRI can non-invasively quantify OEF in stroke patients, relates to perfusion status, and is sensitive to OEF changes over time. Clinical trial registration: Longitudinal MRI examinations of patients with brain ischemia and blood brain barrier permeability; clinicaltrials.org :NCT02077582.

Keywords: Acute ischemic stroke; MRI; oxygen extraction fraction; penumbra; quantitative susceptibility mapping.

Publication types

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

MeSH terms

  • Aged
  • Aged, 80 and over
  • Disease Susceptibility
  • Female
  • Humans
  • Hypoxia, Brain* / blood
  • Hypoxia, Brain* / diagnostic imaging
  • Longitudinal Studies
  • Magnetic Resonance Imaging*
  • Male
  • Middle Aged
  • Oxygen / blood*
  • Perfusion
  • Stroke* / blood
  • Stroke* / diagnostic imaging

Substances

  • Oxygen

Associated data

  • ClinicalTrials.gov/NCT02077582