Non-invasive Measurement Of Hemoglobin Oxygen Saturation (SaO2) In Blood Vessel Phantoms Using Dual-wavelength Photo-thermal Oct

Abstract

 

Purpose:

 

The goal of this study was to develop and validate a novel approach entitled Dual-Wavelength Photothermal Optical Coherence Tomography (DWP-OCT) to measure hemoglobin oxygenation saturation (SaO2) in blood vessel phantoms with high depth resolution.

 

Methods:

 

DWP OCT was used to measure SaO2 levels in porcine arterial blood phantoms with 330 µm internal diameter. The blood vessel phantoms were excited with intensity modulated light. The relationship between optical path length changes in the phantoms and absorbed energy of excitation light was used to calculate SaO2 levels. DWP OCT SaO2 of the blood samples at graded oxygenation levels were correlated with independent blood-gas SaO2 measurements.

 

Results:

 

Fig. A shows a DWP OCT data set at different sample depths. The depth positions are: 1 - the upper air-vessel, 2 - upper and 3 - lower blood-vessel, 4 - vessel-epoxy, 5 - epoxy-glass slide interfaces. At the 800 nm excitation wavelength, the absorption was similar for all samples with graded oxygenation levels, but at the 765 nm wavelength, the absorption for deoxygenated blood was 2.46 times greater than oxygenated blood. DWP OCT SaO2 was linearly correlated with blood-gas SaO2, with the averaged difference of 4.1% between the two methods (Fig. B).

 

Conclusions:

 

This study developed and validated the sensitivity of DWP OCT to detect graded SaO2 levels in blood vessel phantoms. DWP OCT may be useful in identifying abnormal tissue oxygenation in various retinal disorders such as diabetic retinopathy.  

 

Keywords: diabetic retinopathy • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • blood supply