Speckle-illumination spatial frequency domain imaging with a stereo laparoscope for profile-corrected optical property mapping

TL;DR

This paper presents a compact stereo laparoscope integrating speckle-illumination spatial frequency domain imaging and active stereo depth estimation to accurately map tissue optical properties in complex geometries, enhancing minimally invasive surgical guidance.

Contribution

It introduces a novel stereo laparoscope combining active stereo and speckle-illumination SFDI for profile-corrected optical property mapping in tissues.

Findings

Accurate optical property maps in phantoms and in-vivo studies.

Profile correction improves mapping accuracy for complex geometries.

Demonstrated effective 3D profilometry with minimal images.

Abstract

We introduce a compact, two-camera laparoscope that combines active stereo depth estimation and speckle-illumination spatial frequency domain imaging (si-SFDI) to map profile-corrected, pixel-level absorption and reduced scattering optical properties in tissues with complex geometries. Our approach uses multimode fiber-coupled laser illumination to generate high-contrast speckle patterns, requiring only two images for optical property estimation. We demonstrate 3D profilometry using active stereo from low-coherence RGB laser flood illumination, which corrects for measured intensity variations caused by object height and surface angle differences. Validation against conventional SFDI in phantoms and an in-vivo human finger study showed good agreement, with profile-correction improving accuracy for complex geometries. This stereo-laparoscopic implementation of si-SFDI provides a simple method to obtain accurate optical property maps through a laparoscope, potentially offering quantitative endogenous contrast for minimally invasive surgical guidance.