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Simultaneous Data Collection of fMRI and fNIRS Measurements Using a Whole-Head Optode Array and Short-Distance Channels
Published on: October 20, 2023
Depth sensitivity and source-detector separations for near infrared spectroscopy based on the Colin27 brain template
Gary E Strangman1, Zhi Li, Quan Zhang
1Neural Systems Group, Massachusetts General Hospital/Harvard Medical School, Charlestown, Massachusetts, USA. strang@nmr.mgh.harvard.edu
Plos One
|August 13, 2013
Summary
Near-infrared neuromonitoring (NIN) spatial sensitivity increases with source-detector separation up to 65 mm. NIN signals are primarily sensitive to the outermost 10-15 mm of the adult human brain.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Medical Physics
Background:
- Near-infrared spectroscopy (NIRS) is a non-invasive neuroimaging technique.
- Understanding NIRS sensitivity in realistic head models is crucial for accurate brain monitoring.
- Previous characterizations of NIRS spatial and depth sensitivity were limited.
Purpose of the Study:
- To characterize the spatial sensitivity profile of NIRS to brain tissue.
- To evaluate NIRS sensitivity as a function of depth in a realistic head model.
- To assess the impact of NIRS instrument sensitivity on detecting brain activation.
Main Methods:
- Conducted 3,555 Monte Carlo simulations using the adult male Colin27 brain template.
- Analyzed NIRS sensitivity to brain tissue based on source-detector separation.
- Modeled NIRS sensitivity to tissue depth using an exponential decay formula.
Main Results:
- NIRS sensitivity to brain tissue monotonically increased with source-detector separation up to 65 mm.
- Gray matter sensitivity increased by approximately 4% for every 10 mm increase in separation (up to 45 mm).
- NIRS sensitivity decreased exponentially with depth, following S=0.75*0.85(depth), with signals biased towards the superficial 10-15 mm.
Conclusions:
- Detailed spatial and depth sensitivity maps for NIRS in a realistic head model were established.
- Findings provide guidance for interpreting NIRS signals and optimizing experimental design.
- Enhanced understanding facilitates the development of improved NIRS probes and instruments for neuromonitoring.
