Oxyhemoglobin and Cerebral Blood Flow Transients Detect Infarction in Rat Focal Brain Ischemia

Area of Science:

• Neuroscience
• Biomedical Optics
• Ischemic Stroke Research

Background:

• Spreading depolarizations (SD) are neuronal events linked to brain injuries like ischemic stroke.
• Current human monitoring relies on invasive electrocorticography (ECoG).
• Diffuse optical monitoring offers a non-invasive approach to detect SD-related hemodynamic changes.

Purpose of the Study:

• To assess the clinical utility of optical monitoring of flow and hemoglobin transients for detecting infarction in rat focal brain ischemia.
• To analyze the association between SD-related optical transients and infarct size.

Main Methods:

• Continuous optical imaging (Laser Speckle, Optical Intrinsic Signal) of flow, oxy-hemoglobin, and deoxy-hemoglobin in rats post-ischemia.
• Analysis of transient parameters (amplitude, slope, duration, morphology) in relation to infarct assessment via brain slice staining.
• Utilized nine circular regions of interest (ROI) to differentiate infarcted from non-infarcted tissue.

Main Results:

• Flow transient morphology, positive amplitude, positive slope, and total amplitude showed strong association with infarction (p < 0.001).
• Hemoglobin transients (oxy- and deoxy-hemoglobin) also demonstrated significant associations with infarction.
• Specific parameters like oxy-hemoglobin morphology, amplitude, slope, and deoxy-hemoglobin slope and duration were linked to infarct presence.

Conclusions:

• Flow and hemoglobin transients accompanying spreading depolarizations are valuable indicators for detecting infarction.
• Non-invasive diffuse optical monitoring shows promise as an alternative to ECoG for brain injury assessment.
• These findings support the clinical utility of optical methods in managing conditions like ischemic stroke.