Feature Of The Week 5/26/2013: University of Texas at Austin Investigates Dual-Wavelength Photothermal OCT for Imaging Microvasculature Blood Oxygen Saturation
A swept-source dual-wavelength photothermal optical coherence tomography (DWP-OCT) is demonstrated for imaging and measurement of microvasculature oxygen saturation (SO2). DWP-OCT is capable of recording three-dimensional images of tissue and depth-resolved phase variation in response to photothermal excitations in two different wavelengths (770 and 800 nm). Two phantom microvessels with different inner-diameter size (50 and 300 μm) were constructed, porcine blood with various SO2 levels were prepared for the experiment. Phantom microvessels were imaged and blood SO2 levels measured using DWP-OCT are compared with values provided by a commercial oximeter. Propagation error analysis suggests DWP-OCT is feasible for measurement of blood SO2 higher than 60%, which covers the range from veins (70%) to arteries (99%). Influence of blood flow on DWP-OCT SO2 was investigated by using a syringe pump to introduce blood flow with speeds 0-17mm/s, DWP-OCT is demonstrated to remain stable when flow speed is less than 13 mm/s in phantom microvessel. A mathematical model was constructed to investigate the impact of thermal diffusion on DWP-OCT measurement; simulation suggests that thermal diffusion introduces a 3% systematic artifact that over-estimates SO2.
For more information see recent Article. Courtesy of Biwei Yin from University of Texas at Austin.