Beyond backscattering: Optical neuroimaging by BRAD

TL;DR

This paper introduces BRAD, a novel OCT imaging method using few-mode fibers to simultaneously capture bright and dark field information, enhancing tissue contrast and enabling detailed biomedical imaging.

Contribution

The study presents a new BRAD OCT technique leveraging few-mode fibers to access angular scattering information, improving tissue differentiation and contrast in biomedical imaging.

Findings

Enhanced contrast in ex vivo tumor tissue imaging

Successful differentiation of microparticle sizes

Improved detection of Alzheimer's plaques

Abstract

Optical coherence tomography (OCT) is a powerful technology for rapid volumetric imaging in biomedicine. The bright field imaging approach of conventional OCT systems is based on the detection of directly backscattered light, thereby waiving the wealth of information contained in the angular scattering distribution. Here we demonstrate that the unique features of few-mode fibers (FMF) enable simultaneous bright and dark field (BRAD) imaging for OCT. As backscattered light is picked up by the different modes of a FMF depending upon the angular scattering pattern, we obtain access to the directional scattering signatures of different tissues by decoupling illumination and detection paths. We exploit the distinct modal propagation properties of the FMF in concert with the long coherence lengths provided by modern wavelength-swept lasers to achieve multiplexing of the different modal responses into a combined OCT tomogram. We demonstrate BRAD sensing for distinguishing differently sized microparticles and showcase the performance of BRAD-OCT imaging with enhanced contrast for ex vivo tumorous tissue in glioblastoma and neuritic plaques in Alzheimer's disease.