Quantification of total haemoglobin concentrations in human whole blood by spectroscopic visible-light optical coherence tomography

Abstract

The non-invasive quantification of total haemoglobin concentrations [tHb] is highly desired for the assessment of haematologic disorders in vulnerable patient groups, but invasive blood sampling is still the gold standard in current clinical practice. This work demonstrates the potential of visible-light spectroscopic optical coherence tomography (sOCT) for quantifying the [tHb] in human whole blood. To accurately quantify the [tHb] from the substantial optical attenuation by blood in the visible wavelength range, we used a combination of zero-delay acquisition and focus tracking that ensures optimal system sensitivity at any depth inside the sample. Subsequently, we developed an analysis model to adequately correct for the high scattering contribution by red blood cells to the sOCT signal. We validate our method and compare it to conventional sOCT (without focus tracking and zero-delay acquisition) through ex-vivo measurements on flowing human whole blood, with [tHb] values in the clinical range of 7–23 g/dL. For our method with optimized sensitivity, the measured and expected values correlate well (Pearson correlation coefficient = 0.89, p < 0.01), with a precision of 3.8 g/dL. This is a considerable improvement compared to conventional sOCT (Pearson correlation coefficient = 0.59, p = 0.16; precision of 9.1 g/dL).

Microfluidic organ-on-a-chip model of the outer blood–retinal barrier with clinically relevant read-outs for tissue permeability and vascular structure

“…OCT images were acquired with a home-built visible light system (Suppl. Fig.2) previously described 41,42 . Briefly, the setup was based on an open-air Michelson interferometer, with a supercontinuum light source (SuperK Extreme EXB-6, NKT Photonics, Denmark).…”

Intrinsic spectrally-dependent background in spectroscopic visible-light optical coherence tomography

“…This is relevant in a model of light-tissue interaction where the scattering coefficient or elements of the scattering coefficient a fitted parameter [12].…”

“…The prevalence of linear-in-interpolation in SD-OCT makes the systemic nature of the SDBG highly significant towards the spectroscopic OCT research community. Various background biases have been previously reported [10][11][12][13][14]. For example, in polarizationsensitive OCT (PS-OCT) the noise floor varied in different polarization channels and, therefore, comparing the polarization channels required noise floor correction [11].…”

“…For example, in polarizationsensitive OCT (PS-OCT) the noise floor varied in different polarization channels and, therefore, comparing the polarization channels required noise floor correction [11]. Although researchers previously recognized the existence of SDBG and applied empirical corrections [12,14], a thorough investigation of SDBG's origin, influence on spectroscopic vis-OCT, and correction…”

Visible light optical coherence tomography angiography (vis-OCTA) and local microvascular retinal oximetry in human retina

“…One advantage of vis-OCT is its spatio-spectral analysis within the microvasculature for label-free oximetry (i.e. measuring hemoglobin oxygen saturation, sO2) [4,[13][14][15][16][17][18][19]. Compared to 2D hyperspectral imaging modalities [20,21], vis-OCT's precise 3D localization of blood vessels excludes a myriad of confounding factors from other tissue depths, enabling accurate and reliable oximetry measurements.…”