Diffuse optical tomography (DOT) uses near-infrared light spectroscopy (NIRS) to measure changes in cerebral hemoglobin concentration. Anatomical interpretations of the location that generates the hemodynamic signal requires accurate descriptions of the cranio-cerebral relations and DOT sensitivity to the underlying cortical structures. Such information is limited for pediatric populations because they undergo rapid head and brain development. The present study used spatial scalp projection and photon propagation simulation methods to examine scalp-to-cortex distance, scalp-location-to-ROI mapping, and DOT sensitivity profiles in realistic head models based on MRIs. We investigated age-related differences in these measures among infants ranging from 2 weeks to 24 months with narrow age bins, children (4 and 12 years) and adults (20 to 24 years). There were age-group differences in the scalp-to-cortex distances in infancy. The developmental increase was magnified in children and adults. There were systematic age-related differences in the probabilistic mappings between scalp locations and cortical ROIs. The DOT sensitivity profiles displayed decreased fluence strength with increased penetration depth across groups. There were age-related differences in the DOT sensitivity profiles across a wide range of source-detector channel separations. Our findings have important implications in the design of sensor placement and DOT image reconstruction in NIRS and fNIRS research. Age-appropriate realistic head models should be used to provide anatomical guidance for standalone DOT data in infants.
bioRxiv Subject Collection: Neuroscience