Endoscopic imaging of white matter fiber tracts using polarization-sensitive optical coherence tomography

•White matter tracts (WMT) are optically anisotropic and exhibit birefringence.•Polarization-sensitive optical coherence tomography (PSOCT) measures birefringence.•Depth-resolved vectorial birefringence reveals WMT and their orientation.•Endoscopic PSOCT images WMT in fresh intact brain tissue with narrow-gauge probes.•Endoscopic imaging may provide feedback on WMT during neurosurgical procedures. Polarization sensitive optical coherence tomography (PSOCT) has been shown to image and delineate white matter fibers in a label-free manner by revealing optical birefringence within the myelin sheath using a microscope setup. In this proof-of-concept study, we adapt recent advancements in endoscopic PSOCT to perform depth-resolved imaging of white matter structures deep inside intact porcine brain tissue ex-vivo, through a small, rotational fiber probe. The probe geometry is comparable to microelectrodes currently used in neurosurgical interventions. The presented imaging system is mobile, robust, and uses biologically safe levels of optical radiation making it well suited for clinical translation. In neurosurgery, where accuracy is imperative, endoscopic PSOCT through a narrow-gauge fiber probe could provide intra-operative feedback on the location of critical white matter structures. [Display omitted]