Intracranial functional near-infrared spectroscopy: an animal feasibility study

Area of Science:

• Neuroscience
• Biomedical Engineering

Background:

• Functional Near-Infrared Spectroscopy (fNIRS) offers non-invasive cerebral hemodynamic monitoring but is limited by shallow penetration and scalp noise.
• A novel intracranial fNIRS (ifNIRS) system with depth optrodes and optical anchor bolts aims to overcome these limitations.

Purpose of the Study:

• To investigate the feasibility of the ifNIRS system in a swine model.
• To assess ifNIRS's ability to detect hemodynamic changes during controlled interventions.

Main Methods:

• Three swine were implanted with the ifNIRS system, featuring optical anchor bolts (OABs) and depth optrodes (DO).
• Hemodynamic changes were recorded using OAB-to-OAB and DO-to-OAB channels during hypotonic saline infusion and blood withdrawal.
• Hemoglobin concentration changes were analyzed using the Beer-Lambert equation.

Main Results:

• A decrease in total hemoglobin (tHb) was observed during blood withdrawal across relevant channels.
• Variable tHb patterns were noted during hypotonic saline infusion.
• Postmortem analysis revealed minor hemorrhages near OABs, with no intracerebral or heat-related injuries.

Conclusions:

• The ifNIRS system demonstrated feasibility in detecting hemodynamic changes in vivo.
• ifNIRS shows potential for enhancing cerebral hemodynamic monitoring and diagnostic accuracy in invasive procedures.
• Further technical refinements are necessary for optimal clinical application.