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Title: Development of a multi-distance, multi-channel broadband near-infrared spectroscopy system to investigate the spatial variation in cellular oxygen metabolism in the healthy and injured adult human brains
Author: Phan, Phong Thanh
ISNI:       0000 0004 7230 0344
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2018
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This PhD thesis describes the progressive development of a multi-channel, multi-distance broadband NIRS system designed to measure the concentration changes in oxygenated haemoglobin (HbO2), deoxygenated haemoglobin (HHb), and especially the oxidation state of cytochrome-c-oxidase (oxCCO) across multiple regions of the adult human brain. The system was developed using an iterative approach, through two major iterations. At each iteration, in vivo tests in healthy adult volunteers were performed to test the system capability. The first iteration was the pseudo broadband diffuse optical tomography system, achieved by physically moving one source fibre and eight detector fibres across multiple positions in a fixed 3D printed probe holder. A functional activation task involving the visual cortex was used as an in vivo test of this approach. The second iteration was the full multi-channel, multi-distance broadband NIRS system, achieved by increasing the number of source and detector fibres and integrating a time-multiplexing mechanism for the sources. The capability of this system was tested using functional activation tasks involving both the visual and frontal cortices. The final version of the system was then used in the neurointensive care unit to monitor the frontal regions of patients with acute brain injury, demonstrating the capability for monitoring the temporal and spatial variations in cerebral haemodynamics and oxygen metabolism. The multi-channel, multi-distance broadband NIRS measurements acquired from various functional activation studies and the clinical study have provided evidence for the existence of spatially dependent changes in [oxCCO] signal. More importantly, they show that the spatial variation in the changes in [oxCCO] can be monitored using a multi-channel broadband NIRS approach. The measurements collected during various stages of system development have allowed the implementation of the oxCCO image reconstruction algorithm, reconstructing 3D tomographic images of oxCCO for the first time. The combined developments in hardware engineering, data acquisition, clinical studies and image reconstruction open up a whole new avenue for the investigation of cerebral oxygen metabolism in the healthy and injured adult human brain.
Supervisor: Elwell, C. ; Tachtsidis, I. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available