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Proceedings Paper

Characterization of a hybrid diffuse correlation spectroscopy and time-resolved near-infrared spectroscopy system for real-time monitoring of cerebral blood flow and oxygenation
Author(s): K. Verdecchia; M. Diop; Albert Lee; K. St. Lawrence
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Paper Abstract

The combination of near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) offers the ability to provide real-time monitoring of cerebral oxygenation, blood flow and oxygen consumption. However, measuring these parameters accurately requires depth-sensitive techniques that can remove the effects of signal contamination from extracerebral tissues. Towards this goal, we developed and characterized a hybrid DCS/time-resolved (TR)-NIRS system. Both systems acquire data at three source-detector distances (SDD: 7, 20 and 30 mm) to provide depth sensitivity. The TR-NIRS system uses three pulsed lasers (760, 810, and 830 nm) to quantify tissue optical properties, and DCS uses one continuous-wave, long coherence length (>5 m) laser (785 nm) for blood flow monitoring. The stability of the TR-NIRS system was characterized by continuously measuring the instrument response function (IRF) for four hours, and a warmup period of two hours was required to reduce the coefficient of variation of the extracted optical properties to < 2%. The errors in the measured optical properties were <10% at SDDs of 20 and 30 mm; however, the error at 7 mm was greater due to the effects of the IRF. The number of DCS detectors at each SDD and the minimum count-rate (20 kHz per detector resulting in <10% uncertainty in the extracted blood flow index) were optimized using a homogenous phantom. The depth sensitivity was assessed using a two-layer phantom, with the flow rate in the bottom layer altered to mimic cerebral blood flow.

Paper Details

Date Published: 4 March 2015
PDF: 7 pages
Proc. SPIE 9313, Advanced Biomedical and Clinical Diagnostic and Surgical Guidance Systems XIII, 931310 (4 March 2015); doi: 10.1117/12.2079457
Show Author Affiliations
K. Verdecchia, Lawson Health Research Institute (Canada)
Western Univ. (Canada)
M. Diop, Lawson Health Research Institute (Canada)
Western Univ. (Canada)
Albert Lee, Western Univ. (Canada)
K. St. Lawrence, Lawson Health Research Institute (Canada)
Western Univ. (Canada)

Published in SPIE Proceedings Vol. 9313:
Advanced Biomedical and Clinical Diagnostic and Surgical Guidance Systems XIII
Anita Mahadevan-Jansen; Tuan Vo-Dinh; Warren S. Grundfest M.D.; Quan Liu, Editor(s)

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