Impact of temporal resolution on estimating capillary RBC-flux with optical coherence tomography

Abstract

© 2017 Society of Photo-Optical Instrumentation Engineers (SPIE). Optical coherence tomography (OCT) has been used to measure capillary red blood cell (RBC) flux. However, one important technical issue is that the accuracy of this method is subject to the temporal resolution (Δt) of the repeated RBC-passage B-scans. A ceiling effect arises due to an insufficient Δt limiting the maximum RBC-flux that can be measured. In this letter, we first present simulations demonstrating that Δt=1.5 ms permits measuring RBC-flux up to 150 RBCs/s with an underestimation of 9%. The simulations further show that measurements with Δt=3 and 4.5 ms provide relatively less accurate estimates for typical physiological fluxes. We provide experimental data confirming the simulation results showing that reduced temporal resolution (i.e., a longer Δt) results in an underestimation of mean flux and compresses the distribution of measured fluxes, which potentially confounds physiological interpretation of the results. The results also apply to RBC-passage measurements made with confocal and two-photon microscopy for estimating capillary RBC-flux.