Depth-resolved blood oxygen saturation assessment using spectroscopic common-path Fourier domain optical coherence tomography.

Although spectroscopic optical coherence tomography (OCT) has been shown to be a promising method for measuring blood oxygen saturation with high-spatial resolution and accuracy, there are several technical issues that need to be addressed before it could become a practical method. In this letter, we have attempted to address two issues that could significantly improve the quantitative assessment of blood oxygen saturation level. First, we have implemented a spectral normalization technique to eliminate the spectral modulation induced by the wavelength-distance-dependent point spread function (PSF) of OCT's. Second, to reduce the spectral speckle noise due to the highly scattering blood, we have implemented a spatial low-pass filter to the 2-D OCT dataset consisting of spectra obtained at different lateral positions. We have assessed the effectiveness of these methods using common-path OCT system. Results showed that we were able to extract unambiguous depth-resolved, SO(2)-dependent spectroscopic information from 1-D and 2-D OCT images, which could be used to accurately assess the SO(2) level.