Abstract

Optical methods are attractive tools for neuromonitoring given their safety and sensitivity to key markers of brain health: tissue oxygenation can be assessed by near-infrared spectroscopy (NIRS) and cerebral blood flow by diffuse correlation spectroscopy (DCS). Although the application of these tools to neonatal patients is fairly straightforward, since it is reasonable to model the head as an optically homogeneous medium, their use with adult patients is more complicated due to substantial signal contamination caused by hemodynamic fluctuations in the extracerebral (EC) tissue. The purpose of this study was to assess the magnitude of this contamination by acquiring NIRS and DCS data in response to a hypercapnic challenge with and without scalp contributions. Scalp blood flow was impeded by a pneumatic tourniquet, which was confirmed by dynamic contrast-enhanced (DCE) NIRS. The results showed that EC contamination for intensity measurements could be as high as 75%; however, using time-resolved detection can reduce this value to 30%.

© 2019 SPIE/OSA