Microscope Integrated Realtime High Density 4D MHz-OCT in Neurosurgery: a Depth and Tissue Resolving Visual Contrast Channel and the Challenge of Fused Presentation

Microscope integrated realtime 4D MHz-OCT operating at high scanning densities are capable of capturing additional visual contrast resolving depth and tissue. Even within a plain C -scan en-face projection structures are recognizable, that are not visible in a white light camera image. With advanced post processing methods, such as absorbtion coe icient mapping, and morphological classifiers more information is ex traced. Presentation to the user in an intuitive way poses practical challenges that go beyond the implementation of a mere overlay display. We present our microscope integrated high speed 4D OCT imaging system, its clinical study use for in-vivo brain tissue imaging, and user feedback on the presentation methods we developed. In neurosurgery the de-facto standard contrast agents used for visibly highlighting brain tumors are Fluorescin and ALA, both of which come with certain caveats. As part of a clinical study we developed a microscope integrated real time 4D MHz-OCT system, operating as high scanning densities, with the intent of creating visual tissue contrast without the use of such contrast agents. Advanced post processing methods to classify tissue can be derived from static properties such as light absorption and morphology, and from dynamic properties, such as perfusion and elastography. However we also noticed that even in a plain C-scan en-face projection structures of interest could be recognized, that were not visible in the corresponding white light camera image. As part of a clinical study so far we collected data from 20 patients, used it for machine learning based classifiers and developing data presentation modalities for eventual use in a surgical environment. We present the challenges in implementing our microscope integrated high speed 4D OCT imaging system, a selection of the imaging data we collected so far during brain tumor surgeries, and the avenues toward presenting processed data to the surgeon.