Multi-focus averaging for multiple scattering suppression in optical coherence tomography

TL;DR

The paper introduces multi-focus averaging (MFA), a computational method that enhances OCT image contrast by suppressing multiple scattering through multi-focus volume averaging and refocusing, validated on phantom and biological samples.

Contribution

The paper presents a novel MFA technique that suppresses multiple scattering in OCT by leveraging multi-focus acquisition and computational refocusing, improving image contrast in deep tissue imaging.

Findings

MFA improves contrast in phantom and zebrafish OCT images.

MFA outperforms standard complex averaging in contrast enhancement.

The method is cost-effective and compatible with existing OCT systems.

Abstract

Multiple scattering is one of the main factors that limits the penetration depth of optical coherence tomography (OCT) in scattering samples. We propose a method termed multi-focus averaging (MFA) to suppress the multiple-scattering signals and improve the image contrast of OCT in deep regions. The MFA method captures multiple OCT volumes with various focal positions and averages them in complex form after correcting the varying defocus through computational refocusing. Because the multiple-scattering takes different trajectories among the different focal position configurations, this averaging suppresses the multiple-scattering signal. Meanwhile, the single-scattering takes a consistent trajectory regardless of the focal position configuration and is not suppressed. Hence, the MFA method improves the signal ratio between the single- and multiple-scattering signals and improves the image contrast. A scattering phantom and a postmortem zebrafish were measured for validation of the proposed method. The results showed that the contrast of intensity images of both the phantom and zebrafish were improved using the MFA method, such that they were better than the contrast provided by the standard complex averaging method. The MFA method provides a cost-effective solution for contrast enhancement through multiple-scattering reduction in tissue imaging using OCT systems.