Oxygen saturation estimation in brain tissue using diffuse reflectance spectroscopy along stereotactic trajectories.

Area of Science:

• Neuroscience
• Biomedical Optics
• Medical Instrumentation

Background:

• Deep brain stimulation (DBS) involves precise electrode placement in brain tissue.
• Understanding tissue oxygenation and blood volume is crucial for DBS efficacy and safety.
• Diffuse reflectance spectroscopy (DRS) offers a potential method for in vivo tissue analysis.

Purpose of the Study:

• To investigate oxygen saturation (SO2) and blood fraction (fB) in human brain tissue.
• To analyze SO2 and fB variations along deep brain stimulation (DBS) trajectories.
• To evaluate a novel algorithm for estimating SO2 and fB using DRS.

Main Methods:

• DRS measurements were performed at 166 anatomical positions along 20 DBS trajectories targeting STN, Vim, GPi, and Zi.
• Measurements were categorized into gray, white, and light gray matter groups.
• Data were analyzed using a novel algorithm for SO2 and fB estimation.

Main Results:

• Median SO2 levels were 52% in gray matter, 24% in white matter, and 20% in light gray matter.
• Median fB was significantly higher in gray matter (3.9%) compared to white (1.0%) and light gray matter (0.9%).
• No significant differences in SO2 or fB were observed between different DBS target regions.

Conclusions:

• The novel algorithm enables rapid and accurate estimation of SO2 and fB in brain tissue.
• DRS can differentiate tissue types based on oxygenation and blood fraction.
• Findings provide valuable insights into the physiological properties of brain tissue relevant to DBS.