The SOCT system used for the study was based on a standard fiber-optic Michelson interferometer, in which the object arm was modified by the introduction of a resonant scanner (Fig. 1). This technique was applied for the first time by Szkulmowski et al. for the real-time reduction of speckle contrast in the imaging of human eyes and skin, and it was described in detail by Szkulmowski et al.6 In principle, the presented configuration can be applied to any OCT modality. The light emitted by a superluminescent diode (, , BroadlighterT840-HP, Superlum, Ireland) provided the measured axial resolution of 3.5 μm in tissue. After passing the isolator and entering the fiber coupler, the light was split into reference and object arms (splitting ratio, 50/50). In the reference arm, we implemented polarization control of light propagating in the fiber, light attenuation, and dispersion compensation. In the object arm, the light emerging from the fiber was collimated with a 19-mm focal length achromatic lens and directed to the resonant scanner running with 4.6-kHz scanning frequency (Electro-Optical Products Corporation). Two lenses (L1 and L2, ) in 4f configuration relayed the beam to the galvanometer scanners. Lenses L3 and L4 () in 4f configuration relayed the beam to the microscope objective (Thorlabs, ), which allowed for brain imaging with high spatial resolution (10 μm). The OCT signal was detected by a custom-designed spectrometer containing a collimating lens, a volume holographic diffraction grating (; Wasatch Photonics, USA), a telecentric f-theta lens (effective focal length 79.6 mm; Sill Optics), and a 12-bit CMOS line scan camera (spl4096-140 km, Basler Sprint, Germany). The experimentally determined sensitivity of the system was 90 dB, measured with 2 mW power incident at the object and a camera exposure time of 8.6 μs. The imaging speed depended on two camera settings: number of active pixels and exposure time. We have used 2048 of 4096 available camera pixels. The exposure time setting depended on the scan protocols.