Attenuation coefficient as a tool to detect changes in the white matter of the rat brain caused by different types of gliomas and irradiation.

In the present work, we carried out a comparative study of the attenuation coefficient of the white matter of the rat brain during the growth of glial tumors characterized by different degrees of malignancy (glioblastoma 101/8, astrocytoma 10-17-2, glioma C6) and during irradiation. We demonstrated that some tumor models cause a pronounced decrease in white matter attenuation coefficient values due to infiltration of tumor cells, myelinated fiber destruction, and edema. In contrast, other tumors cause compression of the myelinated fibers of the corpus callosum without their ruptures and prominent invasion of tumor cells, which preserved the attenuation coefficient values changeless. In addition, for the first time, the possibility of using the attenuation coefficient to detect late radiation-induced changes in white matter characterized by focal development of edema, disruption of the integrity of myelinated fibers, and a decrease in the amount of oligodendrocytes and differentiation of these areas from tumor tissue and healthy white matter has been demonstrated. The results indicate the promise of using the attenuation coefficient estimated from OCT data for in vivo assessment of the degree of destruction of peritumoral white matter or its compression, which makes this method useful not only in primary resections but also in repeated surgical interventions for recurrent tumors.