Measurement of the hemoglobin oxygen saturation level with spectroscopic spectral-domain optical coherence tomography

Abstract

We report the measurement of the hemoglobin (Hb) oxygen saturation level in human blood with a spectroscopic spectral-domain optical coherence tomography (SSD-OCT) system based on the crossover behavior of Hb and oxyhemoglobin (HbO(2)) absorption coefficients around 800 nm. By calculating the ratio of the exponential decay constant of A-mode scan signal in the long-wavelength range (>800 nm) over that in the short-wavelength range (<800 nm), the relative oxygen saturation level of Hb can be calibrated. Such a relative level can be used for practical diagnosis application after a golden standard is built by comparing the variation of the OCT result with that of a conventional method, such as the use of a blood gas analyzer. In our experiment, the variation curve based on the SSD-OCT measurement, which has the advantages of noninvasive, real-time, and high-resolution measurements, is coincident with that of using a commercial blood gas analyzer.

Are quantitative attenuation measurements of blood by optical coherence tomography feasible?

“…This drawback may be overcome by spectroscopic optical coherence tomography, (S)OCT, where the path length can be accurately controlled. After our [1][2][3] and others' [4][5][6] work using time-domain OCT, Lu et al [7] and Kagemann et al [8] have published changes in the Fourier-domain OCT signal related to oxygenation state. They report important technological steps toward clinical application of SO 2 measurements using SOCT.…”

“…The conversion between pO 2 and SO 2 depends on, e.g., temperature and pH. In the experiment described in [7], a volume of blood is placed in a chamber filled with pure oxygen in which pO 2 was varied between ϳ250 mmHg and ϳ650 mmHg, far above the physiologically found maximum and leading to samples that remain 100% saturated. Their measured signals can therefore not be quantitatively correlated with clinically relevant SO 2 changes.…”

Quantitative microvascular hemoglobin mapping using visible light spectroscopic Optical Coherence Tomography

“…To be truly quantitative, these methods require accounting for the possibly wavelength-dependent attenuation to and from the volume where absorption is to be measured. Alternatively, spectroscopic OCT (SOCT) [4][5][6][7][8][9][10][11][12][13][14] can determine depth-resolved spectra, from which quantification of chromophores based on spectroscopic analysis can then be achieved if the path length is known [15].…”

Optical coherence tomography—current technology and applications in clinical and biomedical research

“…Furthermore, SOCT brings an inherent trade-off between spatial and spectral resolution. In a simplified approach, the concentration of known substances can be determined by comparing the signal attenuation in different wavelength bands [117,118].…”