• Anne E Carolus, Jens Möller, Martin R Hofmann, van de NesJohannes A PJAP3Department of Pathology, University Hospital Bergmannsheil Bochum, Ruhr University Bochum; and., Hubert Welp, Kirsten Schmieder, and Christopher Brenke.
• 1Department of Neurosurgery, University Hospital Knappschaftskrankenhaus Bochum, Ruhr University Bochum.
• J. Neurosurg. 2021 Jan 1; 134 (1): 270277270-277.

ObjectiveOptical coherence tomography (OCT) is an imaging technique that uses the light-backscattering properties of different tissue types to generate an image. In an earlier feasibility study the authors showed that it can be applied to visualize human peripheral nerves. As a follow-up, this paper focuses on the interpretation of the images obtained.MethodsTen different short peripheral nerve specimens were retained following surgery. In a first step they were examined by OCT during, or directly after, surgery. In a second step the nerve specimens were subjected to histological examination. Various steps of image processing were applied to the OCT raw data acquired. The improved OCT images were compared with the sections stained by H & E. The authors assigned the structures in the images to the various nerve components including perineurium, fascicles, and intrafascicular microstructures.ResultsThe results show that OCT is able to resolve the myelinated axons. A weighted averaging filter helps in identifying the borders of structural features and reduces artifacts at the same time. Tissue-remodeling processes due to injury (perineural fibrosis or neuroma) led to more homogeneous light backscattering. Anterograde axonal degeneration due to sharp injury led to a loss of visible axons and to an increase of light-backscattering tissue as well. However, the depth of light penetration is too small to allow generation of a complete picture of the nerve.ConclusionsOCT is the first in vivo imaging technique that is able to resolve a nerve's structures down to the level of myelinated axons. It can yield information about focal and segmental pathologies.

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