title: Cerebral capillary velocimetry based on temporal OCT speckle contrast.
abstract: We propose a new optical coherence tomography (OCT) based method to measure red blood cell (RBC) velocities of single capillaries in the cortex of rodent brain. This OCT capillary velocimetry exploits quantitative laser speckle contrast analysis to estimate speckle decorrelation rate from the measured temporal OCT speckle signals, which is related to microcirculatory flow velocity. We hypothesize that OCT signal due to sub-surface capillary flow can be treated as the speckle signal in the single scattering regime and thus its time scale of speckle fluctuations can be subjected to single scattering laser speckle contrast analysis to derive characteristic decorrelation time. To validate this hypothesis, OCT measurements are conducted on a single capillary flow phantom operating at preset velocities, in which M-mode B-frames are acquired using a high-speed OCT system. Analysis is then performed on the time-varying OCT signals extracted at the capillary flow, exhibiting a typical inverse relationship between the estimated decorrelation time and absolute RBC velocity, which is then used to deduce the capillary velocities. We apply the method toin vivomeasurements of mouse brain, demonstrating that the proposed approach provides additional useful information in the quantitative assessment of capillary hemodynamics, complementary to that of OCT angiography.
authors.affiliation: Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA.
authors.forename: Woo June
authors.initials: WJ
authors.lastname: Choi
authors.affiliation: Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA.
authors.forename: Yuandong
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA.
authors.forename: Wan
authors.initials: W
authors.lastname: Qin
authors.affiliation: Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA.
authors.forename: Ruikang K
authors.initials: RK
authors.lastname: Wang
keywords: (170.2655) Functional monitoring and imaging; (170.4500) Optical coherence tomography; (220.4000) Microstructure fabrication