Analysis of variation in retinal vascular assessment

Hao, H 2014, Analysis of variation in retinal vascular assessment, Doctor of Philosophy (PhD), Electrical and Computer Engineering, RMIT University.

Document type: Thesis
Collection: Theses

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Title Analysis of variation in retinal vascular assessment
Author(s) Hao, H
Year 2014
Abstract Changes in retinal vascular parameters have been shown to be associated with systemic vascular diseases. The current assessment of retinal vascular parameters is based on a solo captured image and computer assisted measurement. The solo image assessment ignores the short term, dynamic change of the retinal vessel and its impact on the measurement. Variation in retinal vessel diameter during the cardiac cycle has been debated in the past, while other retinal vascular parameters have never been verified if affected by the cardiac cycle. There is a lack of comprehensive study on the various sources of variation. This thesis has comprehensively studied the variations from the various sources: (i) human cardiac cycle; (ii) multiple graders; (iii) different software; (iv) repeated photographs; (v) region of interest; (vi) the summary method and (vii) measurement protocol. The results showed there was significant change of retinal individual vessel diameters during the cardiac cycle while this change became non-significant after the individual vessel diameters were summarised using a summary method. Other retinal vascular parameters, such as tortuosity, branching angle, LDR and fractal dimension, had little to no variation over the cardiac cycle. Significant variations were found between graders and different measurement software.

This thesis has shown that variation due to the cardiac cycle can be minimised using the ECG synchronised retinal photographs. The work has also suggested that the significant variations between different graders and the measurement software should be considered in all future studies when comparing their results. Number of strategies such as minimum length of measured vessel that reduce the variability in the measurement have also been identified, and these should be considered when developing new methodologies.

To summarise, this thesis has identified variations and their sources in retinal vascular assessment that will contribute to reduce the variability of vessel measurements leading to improved clinical assessment and identified techniques to mitigate some of these.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Electrical and Computer Engineering
Keyword(s) retinal image analysis
image analysis
cardiac cycle
retinal vessel variation
retinal vascular assessment
image processing
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Created: Thu, 21 May 2015, 09:34:15 EST by Denise Paciocco
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