Phantom and Model-Based Near Infrared Spectroscopy Measurements of Intracranial Hematoma From Infants to Adults

Hemorrhage is a common consequence of traumatic brain injury and can be detected by near-infrared spectroscopy (NIRS)-based noninvasive sensors over scalp. In this study, our aim was to investigate NIRS measurements comprehensively using both phantoms and simulated head models of different age groups from infant to adult with intracranial hematoma development of various sizes and depths for the first time. Physical phantoms of infant (six-month-old), child (two-year-old), adolescent (12-year-old), and young adult head models with intracranial hematoma of varying sizes and depths were built using a multilayer dynamic phantom and evaluated by an NIRS device. Optically similar models with the same geometric configuration as physical phantoms were developed and used in Monte Carlo (MC) simulations. Optical density (OD) from MC simulations and phantom measurements were compared, and the effect of lesions with varying volumes and locations on photon path were investigated in simulations. Results indicated that phantom measurements and simulated model-based measurements are highly significantly correlated. Presence of the hematoma had a larger effect on light traveling in younger group head models, caused an increase in OD from the healthy state to hematoma development, decrease in distance traveled by the light within the head model, and thus decreased sensitivity of the measurement to the brain layer. The findings of this study can guide the detection and localization of lesions for NIRS-based applications in humans at different ages.