Development of a Dual Modality Swept Source Optical Coherence Tomography and Novel Frequency Domain Fluorescence Lifetime Imaging System Using Field Programmable Gate Arrays for Real Time Imaging of Ex-Vivo Human Coronary Artery Atherosclerotic Plaques

Abstract

Atherosclerosis is the leading cause of morbidity and mortality in the United States. It is a systemic and progressive disease process where the arterial wall thickens through inflammation, oxidative stress, and dyslipidemia. This process can lead to the formation of plaques with fibrous caps and lipid-laden cores. Plaques may rupture and result in myocardial infarction, stroke, or limb injury. Future development of systemic or localized therapies for atherosclerosis will depend on a more detailed understanding of plaque development in-vivo. Optical coherence tomography (OCT) and fluorescence lifetime imaging (FLIM) are optical imaging modalities that have the potential to extract complimentary morphological and biochemical information, respectively, from plaques without exogenous contrast agents. OCT has been used intravascularly in humans for years, and combined intravascular OCT and FLIM imaging was recently demonstrated in a rabbit model. Due to the relatively high data rates of OCT and FLIM, real time processing is usually not achievable on a typical computer. However, high speed processing is a necessity in facilitating the clinical applications of dual modality OCT and FLIM systems. Field programmable gate arrays (FPGA)s are reconfigurable integrated circuits that are commonly used for data acquisition and processing applications. This work describes a novel implementation of a frequency domain (FD) FLIM system, real time FPGA signal processing algorithms for swept source OCT and FD FLIM, and ex-vivo human coronary artery macrophage classification using FD FLIM.