A Non-Invasive Approach to Investigating the Intrinsic Cerebrovascular Regulation and Sympathetic Nervous System Using Functional Optical Coherence Tomography (f-OCT)
Date
2024-05-14
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Abstract
While cerebral autoregulation and the sympathetic nervous system are crucial for maintaining stable blood flow to the brain, dysfunctions in these systems can lead to severe disorders, including cardiovascular disease and strokes. To enhance future exploration of these phenomena in humans, this thesis investigates retinal and choroidal vasculature changes under hypoxia using functional Optical Coherence Tomography (f-OCT) imaging. The first hypothesis aims to assess cerebrovascular autoregulation through retinal vasculature monitoring, while the second examines sympathetic nervous system activity by observing choroidal vasculature changes, within the White Mountain database. This investigation seeks to enhance tools for monitoring cerebrovascular function and associated diseases. OCT imaging faces challenges like high noise, artifacts, lack of standardization, and assessment difficulties. To address these, two interconnected vascular bed analysis pipelines were used, along with a novel framework named Q-MCDM (Quasi-Monte Carlo Multi Criteria Decision making). Q-MCDM enhances OCT image processing and evaluation, marking a step towards Interpretable AI in healthcare by optimizing design, execution, and trade-offs in image analysis approaches. Using Q-MCDM for the retinal vascular bed, Frangi's algorithm emerged as the optimal choice for segmentation, achieving a Matthews Correlation Coefficient (MCC) of 0.82, Length (LE) of 0.81, and Area (AR) of 0.86. Conversely, in the choroid vascular bed, the ISODATA method yielded the best results with a Dice coefficient of 0.82, Matthews Correlation Coefficient (MCC) of 0.71, and Area (AR) of 0.79. Significant correlations were observed between vessel perfusion density (VPD) and partial O2 pressure, consistently present across best solutions (r value range = -0.701 to -0.663). Distinct behaviors were observed in the choroid vascular bed's layers. The superficial layer showed increased VPD values, potentially indicating vessel dilation due to parasympathetic or intrinsic autoregulation. In contrast, the deep layer exhibited significant constriction in VPD values, possibly linked to sympathetic nervous system activity. Test/retest assessments confirmed the stability of biological response over time, emphasizing the significance of the findings in understanding intrinsic autoregulation and autonomic nervous system through f-OCT.
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Keywords
Decision-making, Image processing, Cerebrovascular Autoregulation, Sympathetic Nervous System, Optical Coherence Tomography (OCT)
Citation
Safarzadeh, M. (2024). A non-invasive approach to investigating the intrinsic cerebrovascular regulation and sympathetic nervous system using functional Optical Coherence Tomography (f-OCT) (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.