Brain tissue polarimetry under simulated intraoperative conditions: Effects of edema and temperature

In neurosurgical oncology, maximizing tumor resection while preserving neurological function remains a critical challenge, particularly in glioma surgery where tumor borders are difficult to distinguish intraoperatively. Polarimetry-based imaging has emerged as a promising technique for visualizing white matter fiber tracts and differentiating healthy from neoplastic brain tissue. This study evaluates whether brain edema and temperature variations influence polarimetric parameters, potentially introducing noise and complicating intraoperative imaging. To model edema, fresh ex vivo calf brain samples were immersed in distilled water. Polarimetric parameters including depolarization, linear retardance, and the azimuth of the optical axis, were measured at multiple time points over three hours and a half using a wide-field imaging Mueller polarimetric setup. Results show that water absorption affects all polarimetric parameters and complicates fiber tract visualization. We also investigated whether temperature changes influenced polarimetric markers, but found no significant effect. These findings demonstrate that brain edema might alter polarimetric markers and act as a confounding factor in intraoperative imaging, potentially affecting tumor border visualization. The in vivo impact of brain edema remains unclear, and further studies are needed to refine polarimetric imaging for surgical guidance in glioma resection.