Time-resolved spectroscopy and the determination of photon scattering, pathlength, and brain vascular hemoglobin saturation in a population of normal volunteers

David S. Smith M.D.; Warren J. Levy M.D.; S. Carter; NaiGuang Wang; M. Haida; Britton Chance

doi:10.1117/12.154671

14 September 1993 Time-resolved spectroscopy and the determination of photon scattering, pathlength, and brain vascular hemoglobin saturation in a population of normal volunteers

David S. Smith M.D., Warren J. Levy M.D., S. Carter, NaiGuang Wang, M. Haida, Britton Chance

Author Affiliations +

Proceedings Volume 1888, Photon Migration and Imaging in Random Media and Tissues; (1993) https://doi.org/10.1117/12.154671
Event: OE/LASE'93: Optics, Electro-Optics, and Laser Applications in Scienceand Engineering, 1993, Los Angeles, CA, United States

Abstract

Determining the relationship between light absorption and chromophore concentration in brain is complicated by photon scattering, which makes it difficult to determine pathlength. In the current study we apply newly developed phase modulation (PMS) and time-resolved (TRS) spectrometers to determine tissue scattering, pathlength and brain vascular hemoglobin saturation (BVH). PMS measurements were made from both frontal cortices of 36 adults using light guides separated by 4 cm and tightly placed against the forehead. TRS measurements were done with a 5 cm probe separation. For the PMS measurements, changes in phase shift were detected at 754 and 816 nm wavelengths. For TRS, the wavelength was 670 nm in all subjects, and some subjects had additional measurements made at a wavelength of 820 nm. Scattering and the extrapolated pathlength in the absence of hemoglobin were determined from the TRS data. This information was combined with the PMS data to determine BVH. The coefficient variation for the calculated saturation was only 0.04. This suggests both scattering and pathlength have significant intersubject variability and need to be explicitly determined for appropriate calculation of hemoglobin saturation.

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David S. Smith M.D., Warren J. Levy M.D., S. Carter, NaiGuang Wang, M. Haida, and Britton Chance "Time-resolved spectroscopy and the determination of photon scattering, pathlength, and brain vascular hemoglobin saturation in a population of normal volunteers", Proc. SPIE 1888, Photon Migration and Imaging in Random Media and Tissues, (14 September 1993); https://doi.org/10.1117/12.154671

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