What is the role of blood oxygen level-dependent (BOLD) MRI in acute stroke imaging?

Updated: Dec 09, 2020
  • Author: Souvik Sen, MD, MPH, MS, FAHA; Chief Editor: Helmi L Lutsep, MD  more...
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Oxygen extraction fraction (OEF) measured by positron emission tomography (PET) imaging is considered the criterion standard for imaging the ischemic penumbra in acute ischemic stroke. Until now, MR diffusion-perfusion imaging has been the only MR technique that measures this reversibly damaged brain area.

Blood oxygen level–dependent (BOLD) MRI is a technique that can be used to detect deoxyhemoglobin in the cerebral capillaries and veins as an MRI indicator of brain OEF. [4] Evidence suggests that BOLD MRI might provide a better estimation of the ischemic penumbra in acute ischemic stroke compared with MR diffusion-perfusion mismatch.

Resting state functional connectivity (FC) magnetic resonance imaging (MRI) (R-fMRI) measures, within a subject, the temporal correlation of the blood oxygenation level dependent (BOLD) signal across regions without any imposed task, providing a measure of temporal coherence of activity between brain regions. In a pilot study, we found that patients who received intravenous thrombolysis showed changes in resting state networks and functional outcomes over time. These findings point to an intriguing possibility that the improvement of resting state networks may reflect improved efficiency of brain activity that is potentially related to functional outcomes in acute stroke patients. [5]

Further validation of these techniques is required to confirm their clinical value in imaging of acute ischemic stroke.

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