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Single-shot dynamic line-field optical coherence elastography

Manmohan Singh,1, Alexander W. Schill,1, Achuth Nair,1, Salavat R. Aglyamov,2, Irina V. Larina,3, and Kirill V. Larin,1,3
1Department of Biomedical Engineering, University of Houston
2Department of Mechanical Engineering, University of Houston
3Department of Molecular Physiology and Biophysics, Baylor College of Medicine

Abstract

Dynamic optical coherence elastography (OCE) has been established as a powerful technique capable of mapping tissue biomechanical properties. However, there are still some hurdles before OCE becomes clinically established like ultrasound elastography and magnetic resonance elastography, such as speed. Ultra-fast OCE techniques have been developed utilizing rapid scanning and ultra-fast swept sources, but these techniques are limited in their spatial and temporal resolutions. Here, we present an ultra-fast single-shot line-field OCE (LFOCE) technique based on an ultra-fast spectral domain OCT system. The system was based on a Michelson-type interferometer and a supercontinuum broadband light source. A line-beam focus was generated by a cylindrical mirror. The light was expanded and then split by a beamsplitter into the reference and sample arm paths. The collected interference was then dispersed by a transmission grating and focused onto a high-speed 2D camera. The camera operated at a framerate of 25 kHz with 460 lateral pixels, resulting in an A-scan rate of 11.5 MHz. Validation was performed in gelatin phantoms of various concentrations (8%, 10%, and 12% w/w). A focused air-pulse induced elastic waves in the phantoms, which were captured by the LFOCE system. OCE measurements underestimated the elasticity of the phantoms by ~18.5%. OCE measurements were then performed in in situ rabbit corneas in the whole eye-globe configuration, which were cannulated for artificial intraocular pressure (IOP) control. The elastic wave speeds in the cornea at 10, 15, and 20 mmHg IOP were 3.03±0.05, 4.66±0.03, and 8.85±0.08 m/s, respectively. OCE measurements in an in vivo anesthetized rabbit was able to successfully capture the propagation of the elastic wave, demonstrating the ability of the LFOCE system to perform live measurements.

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Manmohan Singh
University of Houston
USA

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