Single-Fiber Diffuse Reflectance Spectroscopy and Spatial Frequency Domain Imaging in Surgery Guidance: A Study on Optical Phantoms.

Polina S Tseregorodtseva,Kirill E Buiankin,Boris P Yakimov,Evgeny A Shirshin,Armais A Kamalov,Gleb S Budylin

doi:10.3390/ma14247502

Abstract

Diffuse reflectance spectroscopy (DRS) and imaging are increasingly being used in surgical guidance for tumor margin detection during endoscopic operations. However, the accuracy of the boundary detection with optical techniques may depend on the acquisition parameters, and its evaluation is in high demand. In this work, using optical phantoms with homogeneous and heterogeneous distribution of chromophores mimicking normal and pathological bladder tissues, the accuracy of tumor margin detection using single-fiber diffuse reflectance spectroscopy and spatial frequency domain imaging was evaluated. We also showed how the diffuse reflectance response obtained at different spatial frequencies with the spatial frequency domain imaging technique could be used not only to quantitatively map absorption and scattering coefficients of normal tissues and tumor-like heterogeneities but also to estimate the tumor depth localization. The demonstrated results could be helpful for proper analysis of the DRS data measured in vivo and for translation of optical techniques for tumor margin detection to clinics.

Highlights

Optical techniques are increasingly being used for intraoperative diagnostics to improve the sensitivity and specificity of tumor margin detection
In this work, using PDMS-based optical phantoms with homogeneous and heterogeneous distributions of the chromophores mimicking optical properties of normal and pathological bladder cancer, we evaluated how the diffuse reflectance parameters and Diffuse reflectance spectroscopy (DRS)-based tumor margin assessment obtained using the single-fiber scheme and spatial frequency domain imaging (SFDI) depend on the detection parameters, e.g., on the position of the fiber relative to the tissue surface, and the properties of the chromophoric inhomogeneities
To evaluate the applicability of diffuse reflectance spectroscopy and imaging for intraoperative diagnostics of tumor margins implemented as a single-fiber scheme and SFDI-scheme, the optical phantoms that simulate the properties of tissues were prepared

Summary

Introduction

Optical techniques are increasingly being used for intraoperative diagnostics to improve the sensitivity and specificity of tumor margin detection. The diffusely reflected light could be captured using various imaging schemes; some of them, like narrow-band imaging, are already used in clinically approved cystoscopes [15,16]. Another possibility is using a single optical fiber inserted in the endoscope, which allows measuring the signal from a specific point of the tissue. One of the prospective imaging techniques based on diffuse reflectance of light is the spatial frequency domain imaging (SFDI) method [17,18,19]. SFDI can be implemented as an endoscopic system [21,22]

Methods

Results

Conclusion