Spectral characterization of liquid hemoglobin phantoms with varying oxygenation states

Abstract

Significance: For optical methods to accurately assess hemoglobin oxygen saturation in vivo, an independently verifiable tissue-like standard is required for validation. For this purpose, we propose three hemoglobin preparations and evaluate methods to characterize them.Aim: To spectrally characterize three different hemoglobin preparations using multiple spectroscopic methods and to compare their absorption spectra to commonly used reference spectra.Approach: Absorption spectra of three hemoglobin preparations in solution were characterized using spectroscopic collimated transmission: whole blood, lysed blood, and ferrous-stabilized hemoglobin. Tissue-mimicking phantoms composed of Intralipid, and the hemoglobin solutions were characterized using spatial frequency-domain spectroscopy (SFDS) and enhanced perfusion and oxygen saturation (EPOS) techniques while using yeast to deplete oxygen.Results: All hemoglobin preparations exhibited similar absorption spectra when accounting for methemoglobin and scattering in their oxyhemoglobin and deoxyhemoglobin forms, respectively. However, systematic differences were observed in the fitting depending on the reference spectra used. For the tissue-mimicking phantoms, SFDS measurements at the surface of the phantom were affected by oxygen diffusion at the interface with air, associated with higher values than for the EPOS system. Conclusions:We show the validity of different blood phantoms and what considerations need to be addressed in each case to utilize them equivalently.

Development of a platform for broadband, spectra-fitted, tissue optical phantoms

“…Phantoms with wavelength-dependent optical properties similar to tissue are usually achieved by directly using biological chromophores, such as whole blood or hemoglobin, to provide absorption and lipid emulsions, such as Intralipid, to provide scattering 3 – 7 Though simple aqueous solutions can be used, these additions can also be suspended in a biologically compatible gelatin- or agar-based hydrogel to produce solid, moldable phantoms 6 , 8 – 10 Although this can result in spectrally accurate phantoms for a wide range of tissue types, the organic nature of both the chromophores and matrix materials inherently limits the shelf-life of these phantoms to somewhere between a few hours and a couple weeks, depending on environmental conditions 1 , 5 , 6 , 9 .…”

Evaluation of a melanoma screening framework based on depth resolved light scattering

“…Figure 12 The total attenuation coefficient (μ t ) of white blood cells (WB), red blood cells (LB), and ferrous-stabilized hemoglobin (A0) was measured in both oxygenated (HbO2) and deoxygenated (Hb) samples using the SCT setup. The results were normalized and compared to reference absorption spectra from previous studies by Prahl and Zijlstra et al (Source: Majedy, M., et al [33]).…”

“…The results were compared to reference spectra from previous studies by Prahl for oxyhemoglobin preparations and by Zijlstra et al for deoxyhemoglobin preparations. The residual spectra from these comparisons were also analyzed, including the use of optimal reference spectra for oxyhemoglobin from Prahl and for deoxyhemoglobin from Zijlstra et al (Source: Majedy, M., et al [33])…”

“…With this setup, SFDS can measure the optical properties over a wide range of wavelengths in a broad spectrum. The SFDS system that we use in our experiments measures the optical properties ranging from 450 nm to 1050 nm in a single exposure [30][31][32][33]. SFDS may not be as precise or cover as large of an area as SFDI, but SFDI is usually limited in that it can only measure the optical properties at a select number of specific wavelengths determined by the LEDs used or filters in front of the camera.…”

“…SFDS [25] and SFDI [26], implemented in variety of ways, give the ability to quantify absorption and scattering properties of tissue and other diffusive media in the visible and near infrared ranges [25,26,33,43]. These techniques have shown promise for non-invasively evaluating malignancies [44,45], wound severity [46,47] and tissue viability [48,49] in skin.…”