Polarimetric visualization of healthy brain fiber tracts under adverse conditions: ex vivo studies.

Omar Rodríguez-Núñez,Angelo Pierangelo,Ekkehard Hewer,Tatiana Novikova,Philippe Schucht

doi:10.1364/boe.439754

Abstract

We suggest using the wide-field imaging Mueller polarimetry to contrast optically anisotropic fiber tracts of healthy brain white matter for the detection of brain tumor borders during neurosurgery. Our prior studies demonstrate that this polarimetric imaging modality detects correctly the in-plane orientation of brain white matter fiber tracts of a flat formalin-fixed thick brain specimen in reflection geometry [IEEE Trans. Med. Imaging39, 4376 (2020)10.1109/TMI.2020.3018439]. Here we present the results of ex vivo polarimetric studies of large cross-sections of fresh calf brain in reflection geometry with a special focus on the impact of the adverse measurement conditions (e.g. complex surface topography, presence of blood, etc.) on the quality of polarimetric images and the detection performance of white matter fiber tracts and their in-plane orientation.

Highlights

Standard treatment for gliomas includes surgical resection, radiation and pharmacotherapy
We suggest using the multi-spectral wide-field imaging Mueller polarimetry (IMP) for the visualization of healthy brain fiber tracts by measuring the depolarization and birefringence of brain tissue without scanning [32]
In order to improve visibility of in-plane fiber tract orientation within the white matter zone we suggest using a mask based on the depolarization threshold (∆ < 0.85) to remove less depolarizing areas of cortex and zones of specular reflection in the images of the azimuth of the optical axis and to highlight the directions of white matter fiber tracts

Summary

Introduction

Standard treatment for gliomas includes surgical resection, radiation and pharmacotherapy. According to the AWMF guidelines [1] for clinical decision-making, complete resection of the enhancing tumor should be attempted as the first-line therapy in patients with high grade gliomas. Planning of a complete resection depends on localization of the tumor and the neurological function of the surrounding tissue, as well as suspected entity and dignity of the tumor. The failure to identify tumor tissue during surgery is a risk factor for incomplete resection, and poorer prognosis [2,3]. Post-operative neurological deficits related to the excessive resection of infiltrated brain tissue have devastating effects on a patient’s quality of life and survival time, and still occur in >10 % of surgeries for intrinsic brain tumors according to contemporary series [4,5]

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Conclusion