Background: Uric acid crystals have recently been identified as a possible therapeutic target for coronary artery disease. Being subcellular in size, it is difficult to identify these crystals in situ. Micro optical coherence tomography (Micro-OCT) allows one to image subcellular structures with 1–micron resolution. Even though Micro-OCT should be capable of resolving urate crystals, it’s difficult to differentiate these structures from other scattering particles within tissue. In this work we developed a novel polarization sensitive micro OCT (ps-Micro-OCT) system for identification of uric acid crystals.
Methods: A spectrometer based ps-Micro-OCT system was developed using a broadband light source. The broadband input light was divided into reference and sample signals using a beam splitter. The reference signal was further divided into two polarized signals with different polarization states. Reflected reference and sample signals were combined and sent to a spectrometer that recorded the interference signal.
Results: To test the performance of system, a mirror was used as sample and a quarter wave-plate was placed in the sample path. The measured quarter wave-plate angle values matched closely to actual angle values. Next we prepared uric acid crystals in our lab and imaged them using this system.We were able to image and identify these crystals based on polarization measurements.
Conclusion: In this work we imaged and identified uric acid crystals using a newly developed ps-Micro-OCT system. The proposed technique will enable imaging uric acid crystals in coronary artery.
Gargi Sharma, Kanwarpal Singh, Joseph A. Gardecki, and Guillermo J. Tearney, "Imaging birefringent crystals using micro optical coherence tomography (Conference Presentation)," Proc. SPIE 10042, Diagnostic and Therapeutic Applications of Light in Cardiology, 100420L (Presented at SPIE BiOS: January 29, 2017; Published: 19 April 2017); https://doi.org/10.1117/12.2253884.5369982360001.
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