Multi-contrast Jones-matrix optical coherence tomography -- the concept, principle, implementation, and applications

Jones-matrix optical coherence tomography (JM-OCT) is an extension of OCT that provides multiple types of optical contrasts of biological and clinical samples. JM-OCT measures the spatial distribution of the Jones matrix of the sample and also its time sequence. All contrasts (i.e., multi-contrast OCT images) are then computed from the Jones matrix. The contrasts obtained from the Jones matrix include the conventional and polarization-insensitive OCT intensity, cumulative and local phase retardation (birefringence), degree-of-polarization uniformity quantifying the polarization randomness of the sample, signal attenuation coefficient, sample scatterer density, Doppler OCT, OCT angiography, and dynamic OCT. JM-OCT is a generalized version of OCT because it measures the generalized form of the sample information; i.e., the Jones matrix sequence. This review summarizes the basic conception, mathematical principle, hardware implementation, signal and image processing, and biological and clinical applications of JM-OCT. Advanced technical topics, including JM-OCT-specific noise correction and quantity estimation and JM-OCT's self-calibration nature, are also described

Design and development of optical reflectance spectroscopy and optical coherence tomography catheters for myocardial tissue characterization

Catheter ablation therapy attempts to restore sinus rhythm in arrhythmia patients by producing site-specific tissue modification along regions which cause abnormal electrical activity. This treatment, though widely used, often requires repeat procedures to observe long-term therapeutic benefits. This limitation is driven in part by challenges faced by conventional schemes in validating lesion adequacy at the time of the procedure. Optical techniques are well-suited for the interrogation and characterization of biological tissues. In particular, optical coherence tomography (OCT) relies on coherence gating of singly-scattered light to enable high-resolution structural imaging for tissue diagnostics and procedural guidance. Alternatively, optical reflectance spectroscopy (ORS) is a point measurement technique which makes use of incoherent, multiply-scattered light to probe tissue volumes and derive important data from its optical signature. ORS relies on the fact that light-tissue interactions are regulated by absorption and scattering, which directly relate to the intrinsic tissue biochemistry and cellular organization. In this thesis, we explore the integration of these modalities into ablation catheters for obtaining procedural metrics which could be utilized to guide catheter ablation therapy. We first present the development of an accelerated computational light transport model and its application for guiding ORS catheter design. A custom ORS-integrated ablation catheter is then implemented and tested within porcine specimens in vitro. A model is proposed for real-time estimation of lesion size based on changes in spectral morphology acquired during ablation. We then fabricated custom integrated OCT M-mode RF catheters and present a model for detecting contact status based on deep convolutional neural networks trained on endomyocardial images. Additionally, we demonstrate for the first time, tracking of RF-induced lesion formation employing OCT Doppler micro-velocimetry; this response is shown to be commensurate with the degree of treatment. We further demonstrate for the first time spectroscopic tracking of kinetics related to the heme oxidation cascade during thermal treatment, which are linked to tissue denaturation. The pairing of these modalities into a single RF catheter was also validated for guiding lesion delivery in vitro and within live pigs. Finally, we conclude with a proof-of-concept demonstration of ORS as a mapping tool to guide epicardial ablation in human donor hearts. These results showcase the vast potential of ORS and OCT empowered RF catheters for aiding intraprocedural guidance of catheter ablation procedures which could be utilized alongside current practices