An approach to in vivo low-magnification optical coherence tomography for selective monitoring of tissue glucose concentration.

The low-magnification optical coherence tomography (LM-OCT) is expected to enable the quantification of tissue glucose concentration (TGC) by maintaining high spatial resolution while reducing artifacts caused by tissue heterogeneity. In the present study, we report the practical application of LM-OCT using a conventional OCT system, i.e., without compromising spatial resolution, for the selective monitoring of changes in TGC through in vivo experiments using a hairless rat model. A commercially available high-spatial resolution OCT device with a center wavelength of 1300 nm was used to detect the three-dimensional (3D) skin surface structure and the scattering coefficient related to the OCT slope. The grand-averaged OCT signal was employed to estimate the OCT slope, while the original high-resolution OCT signals were used to reconstruct the 3D-structural image. A strong linear correlation was observed between changes in the OCT slope and that in TGC, but not with 2-deoxy-glucose, lactate, or Intralipos (soybean oil).