Development of quantitative diagnostic techniques based on decorrelation of speckle present in Optical Coherence Tomography signals

Author(s)

Lucas Ramos de Pretto

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Pesquisas Energéticas e Nucleares (IPEN/BT)
• Defense date: 2019-10-08

Examining board members

Anderson Zanardi de Freitas; Anderson Stevens Leonidas Gomes; Airton Abrahao Martin; Marcus Paulo Raele

• Advisor: Anderson Zanardi de Freitas

Abstract

According to data from the World Health Organization (WHO), noncommunicable chronic diseases (NCDs) are the major causes of death in the world, especially diabetes mellitus (DM). Of particular importance for DM, the maintenance of high glycemic levels contributes to the impairment of vascular functions. Still, DM directly impacts the quality of life through other factors associated with the disease. Noteworthy is the Diabetic Retinopathy (DR), one of the leading causes of blindness in the world. Optical Coherence Tomography (OCT) is a diagnostic imaging modality based on non-ionizing optical interferometry. Analysis of OCT signal intensity fluctuations, due to a noise pattern called speckle, enables angiographic and flow analysis. This study, then, presents the use of OCT as a diagnostic tool for both: measurement of blood glucose levels and retinal microvasculature analysis in vivo. Thus, new diagnostic techniques for glycemic level control and monitoring and study of diabetic retinopathy are proposed. The results ofor differentiating blood glucose concentration obtained by spatial and temporal analysis methods are encouraging, and show good sensitivity of OCT for ex vivo applications, indicating a potential noninvasive glycemic monitoring technique. In addition, new forms of retinal microvascular analysis allow for early diagnosis of DR severity, which provides information for appropriate treatment in each case. Also, this analysis reveals new information about the angiogenesis of DR. However, adequate knowledge about the acquired images and about the metrics used is required, and a report on these factors has been developed. This thesis demonstrates the importance of developing OCT techniques for clinical applications and health benefits of patients with DM. (AU)

• FAPESP's process: 15/15775-3 - Optical Coherence Tomography signal autocorrelation analysis algorithm applied to blood flow monitoring in mice with Metabolic Syndrome
• Grantee: Lucas Ramos de Pretto
• Support Opportunities: Scholarships in Brazil - Doctorate