Imaging4OND 2022 Abstracts


Area 1 - Imaging4OND

Full Papers
Paper Nr: 1
Title:

Shedding Light on Early Central Nervous System Changes for Alzheimer’s Disease through the Retina: An Animal Study

Authors:

Rui Bernardes, Hugo Ferreira, Pedro Guimarães and Pedro Serranho

Abstract: The World Health Organization (WHO) 2015 projections estimated 75.6 million people living with dementia in 2030, an update from the 66 million estimated in 2013. These figures account for all types of dementia, but Alzheimer’s disease stands out as the most common estimated type, representing 60% to 80% of the cases. An increasing number of research groups adopted the approach of using the retina as a window to the brain. Besides being the visible part of the central nervous system, the retina is readily available through non-invasive imaging techniques such as optical coherence tomography (OCT). Moreover, cumulative evidence indicates that neurodegenerative diseases can also affect the retina. In the work reported herein, we imaged the retina of wild-type and the triple-transgenic mouse model of Alzheimer’s disease, at the ages of one-, two-, three-, four-, eight-, twelve- and sixteen-months-old, by OCT and segmented gathered data using a developed convolutional neural network into distinct layers. Group differences through texture analysis of computed fundus images for five layers of the retina, normative retinal thickness data throughout the observation period of the ageing mice, and findings related to the estimation of the ageing effect of the human genes present in the transgenic group, as well as the classification of individual fundus images through convolutional neural networks, will be presented and thoroughly discussed in the Special Session on ”New Developments in Imaging for Ocular and Neurodegenerative Disorders”.
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Paper Nr: 2
Title:

On the Numerical Solution of the Inverse Elastography Problem for Time-harmonic Excitation

Authors:

Pedro Serranho, Sílvia Barbeiro, Rafael Henriques, Ana Batista, Mário J. Santos, Carlos Correia, José P. Domingues, Custódio Loureiro, João R. Cardoso, Rui Bernardes and Miguel Morgado

Abstract: In this paper we address the numerical solution of the inverse elastography problem, from the knowledge of the excitation field on the boundary and the displacement field in a grid of points within the domain. We suggest using a representation of the solution by the method of fundamental solutions and using a Newton- type method to iteratively approximate the Lamé coefficients of the medium from elastography displacement measurements. We consider a toy model to illustrate the performance of the method.
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Paper Nr: 3
Title:

On the Helmholtz’s Equation Model for Light Propagation in the Cornea

Authors:

Adérito Araújo, Sílvia Barbeiro and Milene Santos

Abstract: To model the incidence and reflection of light in the cornea we can use Maxwell’s equations, which describe the electromagnetic wave’s propagation field. In this paper we will focus on Maxwell’s equations in the time harmonic form which translates in the Helmholtz’s equation. We propose a numerical method based on nodal discontinuous Galerkin methods combined with a strategy which is specially designed to deal with curved domains which arise naturally in our domain of interest for the application.
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Paper Nr: 4
Title:

Swept-source Phase-Stabilized Optical Coherence Tomography Setup for Elastography

Authors:

Ana Batista, Carlos Correia, Sílvia Barbeiro, João Cardoso, José P. Domingues, Rafael Henriques, Custódio Loureiro, Mário J. Santos, Pedro Serranho, Rui Bernardes and Miguel Morgado

Abstract: We present an Optical Coherence Elastography (OCE) system, based on a swept-source Optical Coherence Tomography (OCT) setup, and evaluate its performance in terms of phase stability and minimum detectable displacement. The ability to record sub-pixel movements in samples under dynamic conditions was also assessed. The OCE system has a time stability of 396.9 ± 46.7 ps. The phase stability, given by the standard deviation of the measured phase difference, was 72.44 mrad, which corresponds to a minimum detectable displacement of 6.11 nm. Tests showed that the OCE system can detect and measure sub-pixel movements in samples under dynamic mechanical excitation.
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