Quantification of glucose levels in flowing blood using M-mode swept source optical coherence tomography

The increase of glucose levels in blood changes the viscosity of flowing fluids and shape of the erythrocytes. Both of these can affect the details of light scattering as can be quantified via decorrelation times measured by optical coherence tomography (OCT). The relative contributions of these competing effects have been studied by examining the motion dynamics of deformable asymmetrical (red blood cells, RBCs with ∼7 μm diameter and ∼2 μm thickness) and non deformable symmetrical (polystyrene microspheres, PSM with 1.4 μm diameter) flowing scattering particles. The fluid flow under the action of gravity was modulated by changing the glucose concentrations. Quantitative analysis of the OCT’s M-mode autocorrelation functions enabled the derivations of the translational diffusion coefficients. These systematic studies are aimed at eventual tissue imaging scenarios with speckle-variance OCT to obtain local glucose concentrations maps.