Towards cutaneous blood flow velocity estimation using VISTA processing on a 1.6 MHz FDML OCT system

Atopic dermatitis (AD) often induces vasodilation, potentially impacting the velocity of blood flow within capillaries and vessels. To quantify the velocity change, we have developed and tested a 1.67 MHz 1310 nm Fourier-domain mode-locked (FDML) OCT system for measuring the decorrelation coefficient in blood vessels. This system provides an inter-frame time of 0.33 milliseconds and an A-scan spacing of 10 microns. A flow phantom, comprising a glass capillary tube of 80 μm inner diameter infused with unhomogenized milk by a syringe pump, was designed to test our OCT system mimicking the blood vessel. We collected 280 sequential B-scans at the same Y position of the phantom for a number of the velocity values. Based on variable interscan time analysis (VISTA) processing, we observed a strong correlation between the calculated decorrelation coefficients and the predetermined flow velocities, spanning a range from 0.16 mm/s to 30 mm/s. These findings enable us to explore our clinical hypotheses with in vivo tests.