Multimodal Retinal Imaging in Alzheimer's Disease

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Título:
Multimodal Retinal Imaging in Alzheimer's Disease
Autor: Ashraf, Gizem
Assuntos: Alzheimer's disease ; Amyloid ; Amyloid beta ; Brain ; Dementia ; Diagnosis ; Eye ; Fundus photography ; Hyperspectral imaging ; Multimodal imaging ; Neurology ; OCT ; OCTA ; Ophthalmology ; Optical coherence tomography ; Optical coherence tomography angiography ; Retinal imaging ; Screening ; Tau
Descrição: Background There are over 44 million people living with dementia worldwide, and most have Alzheimer's disease (AD). The current diagnostic methods for AD include brain imaging modalities such as magnetic resonance imaging and positron emission tomography which require significant resources, cost, and time. In contrast, retinal imaging modalities are much more widely available, accessible, and are lower in cost. The retina is an extension of the brain and they share a common embryological origin, thus highlighting the potential role for retinal imaging in the diagnosis of AD. Aims The aims of this thesis are: firstly, to perform a systematic review and meta-analysis to understand and evaluate the current evidence regarding retinal imaging in AD. Secondly, to perform a cross-sectional study of retinal imaging in people with biomarker-defined AD compared to healthy controls by exploring the association between these biomarkers and retinal parameters measured by optical coherence tomography (OCT), optical coherence tomography-angiography (OCT-A), and hyperspectral imaging. Thirdly, to explore the role of multimodal imaging in AD by combining findings from various retinal imaging methods to assess the potential of a composite biomarker of AD. Methods A systematic review of PubMed, EMBASE and Scopus was performed in accordance with PRISMA guidelines. Random-effects meta-analyses of standardised mean difference, correlation and diagnostic accuracy were conducted. The findings of this review were used to guide a cross-sectional study, to examine retinal parameters from OCT, OCT-A, and hyperspectral imaging of 35 people with AD and 38 healthy controls. Finally, a literature review on multimodal imaging was performed, and a novel multimodal model was generated using a machine learning approach. Results Meta-analysis of previous studies demonstrated that in people with AD there was a trend towards thinning in most retinal layers on OCT, increased foveal avascular zone area on OCT-A, and reduced arteriole and venule fractal dimension on fundus photography. The cross-sectional study demonstrated that, when compared to healthy controls, AD patients had no significant differences in retinal thickening in most retinal layers on OCT, significantly higher numbers of branching arterioles and venules on OCT infrared en face images, increased foveal avascular zone area and vessel density changes on OCT-A, and increased hyperspectral scores on hyperspectral imaging. The literature review of multimodal imaging outlined current terminology, approaches and challenges in the field. Finally, a novel multimodal model was generated and its clinical utility and limitations were discussed. Conclusion Prior research has identified associations between a number of retinal imaging parameters and AD, however limitations in study design including small sample sizes and non-biological definition of AD cases combined with heterogeneity in imaging methods and reporting make it difficult to determine the utility of these changes as AD biomarkers. Additional retinal imaging biomarkers were found to be associated with AD in our cross-sectional study of a biologically defined AD cohort and the role of combining retinal imaging parameters from multiple imaging modalities in a multimodal approach was explored. Source: TROVE
Data de criação/publicação: 2023
Idioma: Inglês

Multimodal Retinal Imaging in Alzheimer's Disease

Ashraf, Gizem

2023

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