Hybrid decorrelation optical coherence tomography for quantification of wide-dynamic-range blood perfusion

Accurate quantification of blood perfusion is critical for understanding vascular pathophysiology. Although optical coherence tomography (OCT) can offer an insight into the blood perfusion by measuring three-dimensional blood flow velocity, existing OCT velocimetry techniques based on dynamic light scattering face inaccurate measurements of blood perfusion due to limited measurable dynamic range with a finite sampling frequency dependent on a specific swept-source laser or spectrometer. High-speed saturation or low-speed overestimation makes it challenging to cover the entire parabolic velocity distribution like Poiseuille flow in a blood vessel, in which the non-Newtonian shear-thinning behavior of blood fundamentally governs velocity gradients. Here, we proposed hybrid decorrelation (HD) OCT to enable blood perfusion quantification. HD-OCT interpreted the blood flow velocity at slow regimes based on the temporal intensity correlation function, while with its temporal integration in fast-flow regions. It achieved a measurement of blood flow velocity from 0.5 to 400 mm/s. HD-OCT improved the accuracy of blood perfusion measurement based on a precise cross-sectional velocity distribution.