The current study is aimed at investigating the influence of radiotherapy on the optical properties of white matter in patients with brain gliomas using cross-polarization OCT. It was performed on ex vivo samples of peritumoral white matter collected from patients with primary surgery and patients who underwent a course of radiotherapy before surgery. The enhancement of scattering properties in case of use of radiotherapy was detected and the optical coefficients that most accurately reflect the relationship between the optical and morphological properties of white matter in both groups of patients were determined.
Cross-polarization (CP) OCT is a so-called functional extension of OCT that seems to have benefits in visualization of myelin. During surgery it may be quite useful receiving information concerning myelination rate in white matter surrounding tumor mass. It this study it was shown that the quantification of peritumoral white matter using pseudocolor en-face OCT maps based on three optical coefficients (the rate of attenuation in the co- and cross-channel, and the interchannel attenuation difference) correlated well with histological data. Therefore, accurate quantitative CP OCT assessment of peritumoral white matter condition supports the developing the intraoperative implementation of this method.
Optical coherence tomography (OCT) is a promising method for clarifying the boundaries of the infiltrative brain tumors within surrounding white matter. Since gliomas often tend to grow close to eloquent brain areas, the question of the proximity of the tumor to white matter tracts sharply arise during tumor resection to prevent their damage. Crosspolarization (CP) OCT is a so-called functional extension of OCT that seems to have benefits in visualization of myelin. It looks perspective not just to detect white matter, but also receive information about its condition – the myelination rate and presence of ordered fibers. The aim of this study was to visualize white matter organization of eloquent brain areas with CP OCT using post-processing methods. The ex vivo CP OCT images were collected from autopsy subjects of the human brain. The brain specimens contained white matter of different organization and localization: brainstem, corpus callosum, frontal and parietal tracts, subcortical white matter. Two optical coefficients (attenuation and inter-channel attenuation difference) were calculated for each A-scan and two types of color-coded maps based on them were built. No significant differences based on CP OCT attenuation and inter-channel attenuation difference coefficients were demonstrated between white matter from different brain areas. However, in vivo studies can show conversely results. The detection of white matter microstructure during surgery looks promising therefore additional CP OCT performance build-up can be considered.
OCT is a perspective method for glial tumor margins detection during surgical operation. The challenging clinical problem of improving the functional outcomes of the surgeries on the central nervous system could be solved with the aid of cross-polarization (CP) OCT, which visualizes light backscattered from the sample in two orthogonal polarizations and gives sensitivity to the myelinated fibers. This study aimed to evaluate CP OCT feasibility to distinguish different types of brain tissue during glioma surgery to assess tumor margins and the proximity to the conductive pathways of the brain. Postoperative human specimens (tumorous tissue and peritumoral tissue, n = 40) for ex vivo СP OCT study were taken with considering the location of eloquent brain areas and tracts. Regions of sampling were also recorded at the neuronavigation station. It was shown, that the quantitative characteristics of the OCT signal of the tumor and peritumoral area have quite good correspondence with the tumor location according to the preoperative MRI, and better correlated with histological data. The same results were demonstrated for comparison of the OCT signal of the peritumoral areas and the normal white matter with the MRI-tractography and histological data. In conclusion, the CP OCT method has a high potential for intraoperative application to clarify the presence of infiltration areas and proximity to eloquent brain areas and tracts. The study was supported by RFBR projects No. 18-29-01049_mk and No. 16-32-60178 mol_а_dk.
Optical coherence tomography (OCT) is a promising method of glial tumors borders diagnostics. Nowadays it is possible to use hand-held and microscope mounted OCT devices during tumor removal. But still there are no clearly visual assessment criteria of OCT images, on the basis of which good differentiation between glioma tissue and white matter can be performed. This paper presents such criteria for crosspolarization OCT (CP OCT), which can detect both the scattering and polarization properties of tissues.
In the case of infiltrative brain tumors the surgeon faces difficulties in determining their boundaries to achieve total resection. The aim of the investigation was to evaluate the performance of multimodal OCT (MM OCT) for differential diagnostics of normal brain tissue and glioma using an experimental model of glioblastoma. The spectral domain OCT device that was used for the study provides simultaneously two modes: cross-polarization and microangiographic OCT. The comparative analysis of the both OCT modalities images from tumorous and normal brain tissue areas concurrently with histologic correlation shows certain difference between when accordingly to morphological and microvascular tissue features.
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