68 documents found, page 1 of 7

Provas de Agregação em Matemática: lição, relatório e curriculum

Inverse problems and medical imaging: lecture notes

Lecture notes for the curricular unit of Inverse Problems and Medical Imaging (23036 - https://guiadoscursos.uab.pt/en/ucs/problemas-inversos-e-imagiologia-medica/ ) of the Doctor’s Degree in Applied Mathematics and Modelling of Universidade Aberta.

Retinal OCT-derived texture features as potential biomarkers for early diagnosi...

PURPOSE. Diabetic retinopathy (DR) is usually diagnosed many years after diabetes onset. Indeed, an early diagnosis of DR remains a notable challenge, and, thus, developing novel approaches for earlier disease detection is of utmost importance. We aim to explore the potential of texture analysis of optical coherence tomography (OCT) retinal images in detecting retinal changes in streptozotocin (STZ)-induced dia...

The MFS-SVD method for the laplace equation in three dimensions

The method of fundamental solutions (MFS) has been widely used to numerically solve boundary value problems involving linear partial differential equations. This method is easy to implement computationally and can be very effective for smooth domains and boundary conditions. The main drawback of the MFS is the ill-conditioning of the associated matrices, which may deteriorate the method’s accuracy. We present t...

Early retinal changes in type 2 diabetes detected by texture-based OCT analysis...

Background: Diabetic retinopathy (DR) is often diagnosed many years after diabetes onset, highlighting the need for early diagnosis. The current study aimed to assess whether texture analysis of computed optical coherence tomography (OCT) retinal images can identify (very) early retinal changes. We previously reported retinal texture changes in a type 1 diabetes animal model. This study extends this approach to...

Direct crosstalk between adult human retinas as suggested by interocular transf...

Crosstalk mechanisms between retinas were never documented in humans despite being documented for several other species, including non-human primates. Results of the first-in-human study that documents the crosstalk between retinas by measuring the vascular response in one retina to the photic stimulation of the contralateral eye in health and disease are reported herein. A stimulation apparatus was developed a...

A hybrid method for the time-harmonic inverse acoustic transmission problem

The inverse transmission problem of scattering an acoustic wave by a penetrable object has several applications in various fields such as radar, sonar, geophysical exploration, medical imaging and non destructive testing. Here we propose a numerical hybrid method to inverse acoustic scattering by penetrable obstacles from far-field data in two-dimensions, that extends an iterative decomposition method to the tr...

Improving the conditioning of the method of fundamental solutions for the Helmh...

A new approach to overcome the ill-conditioning of the Method of Fundamental Solutions (MFS) combining Singular Value Decomposition (SVD) and an adequate change of basis was introduced in [1] as MFS-SVD. The original formulation considered polar coordinates and harmonic polynomials as basis functions and is restricted to the Laplace equation in 2D. In this work, we start by adapting the approach to the Helmholt...

Texture for neuroimaging

Texture analysis is an umbrella term for multiple image analysis techniques that quantify and characterize the distribution of the image’s gray levels. It has a natural application in biomedical image analysis, where texture-based techniques are increasingly being incorporated into neuroimaging research. In this chapter, the role of texture analysis in the field of neuroimaging is addressed. Neuroimaging applic...

The hemodynamic response function as a type 2 diabetes biomarker: a data-driven...

Introduction: There is a need to better understand the neurophysiological changes associated with early brain dysfunction in Type 2 diabetes mellitus (T2DM) before vascular or structural lesions. Our aim was to use a novel unbiased data-driven approach to detect and characterize hemodynamic response function (HRF) alterations in T2DM patients, focusing on their potential as biomarkers. Methods: We meshed task-b...