Method for Quantitative Broadband Diffuse Optical Spectroscopy of Tumor-Like Inclusions

Sandhya Vasudevan,Farnoush Forghani,Chris Campbell,Thomas D O’Sullivan,Savannah Bedford

doi:10.3390/app10041419

Sandhya Vasudevan, Farnoush Forghani + Show 3 more

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https://doi.org/10.3390/app10041419

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Abstract

A hybrid reflectance-based diffuse optical imaging (DOI) technique combining discrete wavelength frequency-domain (FD) near-infrared spectroscopy (NIRS) with broadband continuous wave NIRS measurements was developed to quantify the broadband optical properties of deep tumor-like inclusions. This method was developed to more accurately measure the broadband optical properties of human tumors using a compact handheld imaging probe and without requiring a priori spectral constraints. We simulated the reconstruction of absorption and scattering spectra (650–1000 nm) of human breast tumors in a homogeneous background at depths of 0 to 10 mm. The hybrid DOI technique demonstrated enhanced performance in reconstruction of optical absorption with a mean accuracy over all 71 wavelengths of 8.39% versus 32.26% for a 10 mm deep tumor with the topographic DOI method. The new hybrid technique was also tested and validated on two heterogeneous tissue-simulating phantoms with inclusion depths of 2, 7, and 9 mm. The mean optical absorption accuracy over all wavelengths was similarly improved up to 5x for the hybrid DOI method versus topographic DOI for the deepest inclusions.

Highlights

In diffuse optical imaging (DOI), near-infrared (NIR) light is used to noninvasively probe cm-thick biological tissues to map macroscopic structure and function
Different columns correspond to different depths of the tumor simulated from the tissue surface (0, 5, Different columns correspond to different depths of the tumor simulated from the tissue surface (0, and 10 mm), whereas different rows correspond to the ground truth μa and the simulated μa recovery
A hybrid DOI method is presented that combines discrete wavelength FD and broadband CW reflectance measurements for quantitative measurements of the optical properties of deep tissue inclusions with a simple reflectance-based handheld probe configuration

Summary

Introduction

In diffuse optical imaging (DOI), near-infrared (NIR) light is used to noninvasively probe cm-thick biological tissues to map macroscopic structure and function. DOI can identify the distribution and concentrations of NIR tissue optical absorbers, such as oxy-, deoxy- hemoglobin, water, and lipids, and has been widely explored in clinical breast cancer applications [1,2,3]. These studies have demonstrated quantitative analysis of breast tissue (tumor and normal) composition [2,4,5,6], monitoring, and prediction of tumor response to chemotherapy [3,7,8] and differential diagnosis of malignant from benign lesions [9,10,11,12,13].

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