Author

Yali Jia

Date

November 2010

Document Type

Dissertation

Degree Name

Ph.D.

Department

Dept. of Biomedical Engineering

Institution

Oregon Health & Science University

Abstract

Functional microcirculation, a system consisting of intact blood vessels perfused with red blood cells (RBCs), is required for the maintenance of O2 and nutrient delivery to living tissues. Disruption of this system can be indicative of organ dysfunction and is characteristic of various disease pathologies. In vascular diseases, development and maintenance of functional microvasculature are crucial to facilitate the recovery of tissue functions in the body. To quantify changes in microvascular perfusion in animal models of vascular diseases, it is necessary to directly visualize the microcirculation in vivo and quantify functional microvascular blood flow. Although non-invasive methods, such as magnetic resonance imaging (MRI) and ultrasound, have greatly advanced in temporal and spatial resolution, they remain limited in their ability to resolve vascular structures and to assess microhemodynamics at the capillary level. For these reasons, our group has chosen optical microangiography (OMAG) to evaluate microcirculatory function in various disease models. The broad goal of this research is to assess the OMAG technique to image 3D blood flow within microcirculatory tissue beds in vivo, so that it may be accepted as a standard imaging modality for preclinical study on vascular disease. This thesis addresses a number of animal models regarding blood flow under pathological conditions. In particular, we used OMAG for imaging cerebral blood flow (CBF) and peripheral blood flow (PBF). For CBF measurement, we included animal models that represent trauma, stroke and meningeal thrombosis. For PBF measurement, we studied diabetic peripheral neuropathy (DPN). In each animal model, (1) we optimize the scanning protocols and optics to test the feasibility of OMAG for 3D dynamic visualization of specific microvasculature; (2) we establish quantification algorithms to process OMAG data in order to obtain the parameters for tissue perfusion, such as blood volume, vessel density, blood velocity, etc. Based on the OMAG results obtained in this study, we find that 3D OMAG can be a useful tool to non-invasively and quantitatively characterize cerebral tissue perfusion responses due to trauma, stroke and meningeal thrombosis, and peripheral tissue perfusion responses due to diabetes in mouse models. Based on these findings we further conclude that OMAG imaging method in conjunction with the quantifying methods developed on it will provide a new level of information regarding blood flow in the functions of human brain and other organs.

Identifier

doi:10.6083/M4BP00RP

School

School of Medicine

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