In the present study, various combinations of dimensionality reduction methods with data clustering methods for the analysis of biopsy samples of intracranial tumors were investigated. Fresh biopsies of intracranial tumors were studied in the Laboratory of Neurosurgical Anatomy and Preservation of Biological Materials of N.N. Burdenko Neurosurgery Medical Center no later than 4 h after surgery. The spectra of Protoporphyrin IX (Pp IX) fluorescence, diffuse reflectance (DR) and Raman scattering (RS) of biopsy samples were recorded. Diffuse reflectance studies were carried out using a white light source in the visible region. Raman scattering spectra were obtained using a 785 nm laser. Patients diagnosed with meningioma, glioblastoma, oligodendroglioma, and astrocytoma were studied. We used the cluster analysis method to detect natural clusters in the data sample presented in the feature space formed based on the spectrum analysis. For data analysis, four clustering algorithms with eight dimensionality reduction algorithms were considered.

Introduction: The prediction of the fluorescent effect of 5-aminolevulinic acid (5-ALA) in patients with diffuse gliomas can improve the selection of patients. The degree of enhancement of gliomas has been reported to predict 5-ALA fluorescence, while, at the same time, rarer cases of fluorescence have been described in non-enhancing gliomas. Perfusion studies, in particular arterial spin labeling perfusion, have demonstrated high efficiency in determining the degree of malignancy of brain gliomas and may be better for predicting fluorescence than contrast enhancement. The aim of the study was to investigate the relationship between tumor blood flow, measured by ASL, and intraoperative fluorescent glow of gliomas of different grades. Materials and methods: Tumoral blood flow was assessed in 75 patients by pCASL (pseudo-continuous arterial spin labeling) within 1 week prior to surgery. In all cases of tumor removal, 5-ALA had been administered preoperatively. Maximum values of tumoral blood flow (TBF max) were measured, and normalized tumor blood flow (nTBF) was calculated. Results: A total of 76% of patients had significant contrast enhancement, while 24% were non-enhancing. The histopathology revealed 17 WHO grade II gliomas, 12 WHO grade III gliomas and 46 glioblastomas. Overall, there was a relationship between the degree of intraoperative tumor fluorescence and ASL-TBF (R_s = 0.28, p = 0.02 or the TBF; R_s = 0.34, p = 0.003 for nTBF). Non-enhancing gliomas were fluorescent in 9/18 patients, with nTBF in fluorescent gliomas being 54.58 ± 32.34 mL/100 mg/s and in non-fluorescent gliomas being 52.99 ± 53.61 mL/100 g/s (p > 0.05). Enhancing gliomas were fluorescent in 53/57 patients, with nTBF being 170.17 ± 107.65 mL/100 g/s in fluorescent and 165.52 ± 141.71 in non-fluorescent gliomas (p > 0.05). Conclusion: Tumoral blood flow levels measured by non-contrast ASL perfusion method predict the fluorescence by 5-ALA; however, the additional value beyond contrast enhancement is not clear. ASL is, however, useful in cases with contraindication to contrast.

Introduction. Today we observe an increase in brain tumor incidence around the world, and glioma is no exception. Gliomas are still among the most frequently diagnosed primary central nervous system tumors despite a large number of glioma management studies. Their control still remains a challenge. It is necessary to create specialized cryogenic storage with a systematized databank that could provide a basis for more profound studies of their pathogenesis and invasion patterns. There are about 20 biorepository facilities in Russia; however, they do not focus on a particular tumor type. The aim of the study was to develop the spe-cific biobank of glial tumors integrated with a dedicated electronic system containing all associated clinical data necessary for the research purposes. Materials and methods. The required amount of material sampling was carried out during the surgical resec-tion in patients with a preliminary diagnosis of “malignant glioma”, followed by processing, cryopreserva-tion, and passportization. Results. Between August 1, 2018, and April 30, 2020, a total of 1,452 aliquots from 358 subjects were ac-cumulated in the biobank. Each frozen sample corresponded to a paraffin block and provided with the whole set of associated demographic, clinical, histological, and follow-up data. All these records were stored in the electronic information system. During this study, the design of the glioma passport was developed. Conclusion. The development of an appropriate facility is necessary for efficient further experimental re-search. It offers an opportunity for future implementation of personalized treatment methods after a full clinical trial cycle. Keywords: neurooncology, glioma, glioblastoma, biobank, biorepository

The study objective is to describe currently available and optimal methods of central skull base reconstruction. Material and methods. This article describes a 10-year experience of endoscopic surgery in reconstructing the defects after the removal of chiasmosellar tumors. Results. We developed a strategy for assessing the risks for postoperative liquorrhea and choosing an optimal surgical technique. This strategy allows maintaining the incidence of postoperative liquorrhea of 4 %. Conclusion. Autografts are the most widely used material for reconstructing skull base defects after the removal of chiasmosellar tumors. The multilayer reconstruction is more preferable due to the high risk of postoperative liquorrhea.

Diffuse midline gliomas are relatively rare in adults. Regardless of age, all diffuse midline gliomas are routinely examined in our Center for the presence of the H3F3A K27M gene mutation. However, we identified IDH-mutant brainstem glioma in a 42-year-old man for the first time.