Assessment of Gd2O3 nanoparticles as exogenous imaging contrast agent for swept source optical coherence tomography

Abstract

Optical coherence tomography (OCT) is a non-invasive and non-contact imaging technique that uses the reflection of light waves for tissue imaging. Compared to all other OCT variants, the swept-source OCT (SS-OCT) configuration offers higher imaging speed, better signal-to-noise ratio, and more resolution. Despite its numerous advantages, SS-OCT greatly suffers from limited contrast and reduced penetration ability. Over the years, several nanoparticles (NPs) like AgNP, TiO2, ZnO, etc have been exploited extensively as exogenous contrast agents to enhance the image contrast. Subsequently, herein, we have presented gadolinium oxide (Gd2O3) as a potential exogenous contrast agent for 3D non-invasive depth-resolved imaging of animal (chicken breast) tissue using an in-house developed SS-OCT system with centre wavelength of 1060 nm. In this work, OCT imaging of agar filled capillary tubes (phantoms) and chicken breast tissue (in vitro) was performed both with and without the application of Gd2O3 NPs. Scattering coefficient and contrast-to-noise ratio (CNR) calculations were done to study the effect of Gd2O3 NPs on the tissue sample at different time exposures. Post analysing the OCT images, a significant increase, in contrast, observed with time, where both the scattering coefficient (0.4879 mm−1 to 1.3782 mm−1) and the CNR of OCT B-scans (12.42 dB to 42.21 dB) increased substantially.