Quantitative short-wave infrared multispectral imaging of in vivo tissue optical properties.

Robert H Wilson,Bruce J Tromberg,Frank B Jaworski,Rebecca Rowland,Kyle P Nadeau,Anthony J Durkin,Rolf B Saager,Christian Crouzet,Bernard Choi,John Q Nguyen

doi:10.1117/1.jbo.19.8.086011

Robert H Wilson, Bruce J Tromberg + Show 8 more

Open Access

https://doi.org/10.1117/1.jbo.19.8.086011

Copy DOI

Abstract

Extending the wavelength range of spatial frequency domain imaging (SFDI) into the short-wave infrared (SWIR) has the potential to provide enhanced sensitivity to chromophores such as water and lipids that have prominent absorption features in the SWIR region. Here, we present, for the first time, a method combining SFDI with unstructured (zero spatial frequency) illumination to extract tissue absorption and scattering properties over a wavelength range (850 to 1800 nm) largely unexplored by previous tissue optics techniques. To obtain images over this wavelength range, we employ a SWIR camera in conjunction with an SFDI system. We use SFDI to obtain in vivo tissue reduced scattering coefficients at the wavelengths from 850 to 1050 nm, and then use unstructured wide-field illumination and an extrapolated power-law fit to this scattering spectrum to extract the absorption spectrum from 850 to 1800 nm. Our proof-of-principle experiment in a rat burn model illustrates that the combination of multispectral SWIR imaging, SFDI, and unstructured illumination can characterize in vivo changes in skin optical properties over a greatly expanded wavelength range. In the rat burn experiment, these changes (relative to normal, unburned skin) included increased absorption and increased scattering amplitude and slope, consistent with changes that we previously reported in the near-infrared using SFDI.

Highlights

Over the past two decades, optical methods have been widely employed to obtain information about the absorption and scattering content of biological tissues.[1]
Expanding the wavelength range of spatial frequency domain imaging (SFDI) to include the short-wave infrared (SWIR) can potentially provide increased sensitivity to water[3] and lipids,[3,4] both of which have absorption features throughout the SWIR that are more prominent than those found in the NIR
We report on integration of SFDI methods, which we have previously described elsewhere,[1,2,10] with planar illumination and a SWIR camera capable of spectral imaging from 850 to 1800 nm

Summary

Introduction

Over the past two decades, optical methods have been widely employed to obtain information about the absorption and scattering content of biological tissues.[1]. SWIR optical sensing of skin has previously been employed to spectrally characterize porcine[6,7] and human[8,9] skin properties These measurements have largely been performed on ex-vivo tissue samples using integrating sphere based techniques.[6,7,8,9]. We report on integration of SFDI methods, which we have previously described elsewhere,[1,2,10] with planar illumination and a SWIR camera capable of spectral imaging from 850 to 1800 nm This combination of SWIR instrumentation and a hybrid SFDI procedure (using data from both structured and uniform planar light) enables us to obtain tissue

Experimental Methods

Data Analysis Methods and Results

Findings

Discussion and Conclusions