Monte Carlo simulation of light transport through spinal cord and surrounding tissues: impact on spinal cord near-infrared spectroscopy (Conference Presentation)

Introduction: Implantable near-infrared spectroscopy (NIRS) can improve clinical management of spinal cord injury (SCI) patients by continuously monitoring spinal cord oxygenation. This research aims to model light propagation within the spinal cord and the diffuse reflection from its surface to better understand NIRS measurement characteristics. Methods: Monte Carlo simulations were constructed for porcine and human spinal cord geometries using wavelengths between 650 and 950 nm. Spinal cord morphometrics and oxygenation was varied to evaluate their effects on fluence within the spinal cord as well as the diffuse reflection from it. Results: The data indicated that light scattered by the dura mater tends to escape through cerebrospinal fluid without penetrating the spinal cord, leading to a 10-fold decrease in spinal cord fluence. Conclusions: It is essential to evaluate how optical properties and interactions between tissue layers impact spinal cord NIRS measurements for effective translation from animal models to clinical use.