[Non-invasive diagnosis of brain gliomas by histological type using neuroradiomics in standardized regions of interest: towards digital biopsy]. / Neinvazivnaya diagnostika gliom golovnogo mozga po gistologicheskomu tipu s pomoshch'yu neiroradiomiki v standartizirovannykh zonakh interesa: na puti k tsifrovoi biopsii.

The future of contemporary neuroimaging does not solely lie in novel image-capturing technologies, but also in better methods for extraction of useful information from these images. Scientists see great promise in radiomics, i.e. the methodology for analysis of multiple features in medical image. However, there are certain issues in this field impairing reproducibility of results. One such issue is no standards in establishing the regions of interest. OBJECTIVE: To introduce a standardized method for identification of regions of interest when analyzing MR images using radiomics; to test the hypothesis that this approach is effective for distinguishing different histological types of gliomas. MATERIAL AND METHODS: We analyzed preoperative MR data in 83 adults with various gliomas (WHO classification, 2016), i.e. oligodendroglioma, anaplastic oligodendroglioma, anaplastic astrocytoma, and glioblastoma. Radiomic features were computed for T1, T1-enhanced, T2 and T2-FLAIR modalities in four standardized volumetric regions of interest by 356 voxels (46.93 mm3): 1) contrast enhancement; 2) edema-infiltration; 3) area adjacent to edema-infiltration; 4) reference area in contralateral hemisphere. Subsequently, mathematical models were trained to classify MR-images of glioma depending on histological type and quantitative features. RESULTS: Mean accuracy of differential diagnosis of 4 histological types of gliomas in experiments with machine learning was 81.6%, mean accuracy of identification of tumor types - from 94.1% to 99.5%. The best results were obtained using support vector machines and random forest model. CONCLUSION: In a pilot study, the proposed standardization of regions of interest demonstrated high effectiveness for MR-based differential diagnosis of oligodendroglioma, anaplastic oligodendroglioma, anaplastic astrocytoma and glioblastoma. There are grounds for applying and improving this methodology in further studies.

[Magnetic resonance imaging of saccular intracranial aneurysm wall]. / MR-vizualizatsiya sosudistoi stenki meshotchatykh intrakranial'nykh anevrizm.

BACKGROUND: Hemorrhage from intracranial aneurysms is associated with high risk of adverse outcomes. In this regard, surgical treatment of unruptured asymptomatic aneurysms has been actively developed in recent decades. One of the objectives is searching for predictors of aneurysm rupture to clarify the indications for surgery. Non-invasive analysis of vascular wall is actively discussed in last years. OBJECTIVE: To evaluate the possibilities of MRI of ruptured and unruptured intracranial aneurysm walls and determine clinical significance of certain morphological patterns. MATERIAL AND METHODS: The study included 111 patients with 158 ruptured and unruptured saccular aneurysms who underwent MRI according to a special protocol between November 2020 and September 2023. We analyzed each aneurysm regarding features of contrast enhancement and changes in SWAN images. After that, we compared these data with ruptures. RESULTS: Wall of ruptured and unruptured aneurysms can accumulate contrast agent. We found 5 types of contrast enhancement. Thick-layer contrast enhancement was accompanied by 9.6-fold higher risk of aneurysm rupture compared to aneurysms without contrast enhancement. Dark MR signal from intracranial aneurysm wall in SWAN imaging is a significant sign of rupture. CONCLUSION: MRI of the vascular wall is valuable to verify ruptured aneurysms. Unruptured aneurysms can accumulate contrast agent inside the wall, and pattern of accumulation differs from ruptured aneurysms. Morphological analysis is needed to confirm contrast enhancement as a marker of aneurysm rupture.

[The first application of intraoperative mri for analysis of cerebral perfusion in surgical brain revascularization]. / Pervoe primenenie intraoperatsionnoi MRT dlya issledovaniya tserebral'noi perfuzii pri khirurgicheskoi revaskulyarizatsii golovnogo mozga.

BACKGROUND: Effectiveness of surgical revascularization in patients with chronic cerebral ischemia depends on restoration of circulation in the damaged artery. Modern methods do not take into account dynamic changes in cerebral perfusion after extra-intracranial microvascular anastomosis (EICMA) and do not allow timely localizing the areas of persistent perfusion deficit. We propose a new method for determining the tactics of surgical cerebral revascularization based on intraoperative MRI (iMRI) perfusion data. This method provides the earliest information on intraoperative brain reperfusion. OBJECTIVE: To develop the principles of dynamic assessment of cerebral blood flow using intraoperative ASL perfusion during surgical revascularization in patients with chronic cerebral ischemia and to determine the indications for additional anastomoses. MATERIAL AND METHODS: Surgical revascularization with intraoperative MRI perfusion was performed in 27 patients between March 2022 and April 2023. There were 10 patients with post-thrombotic occlusion of internal carotid artery, 4 patients with occlusion of middle cerebral artery and 13 patients with moyamoya disease. All patients underwent MRI before surgery. After imposing the first EICMA, all patients underwent ASL perfusion for analysis of residual hypoperfusion zones, signs of local hyperperfusion and indications or contraindications for additional revascularization with the second donor branch. RESULTS: In all cases, iMRI made it possible to determine the tactics of brain revascularization using one or two EICMA. In 17 cases, ASL perfusion confirmed the targeted improvement of cerebral blood flow (CBF) in the entire hemisphere or middle cerebral artery basin. Only one EICMA was imposed in these cases. In 10 cases, a single anastomosis was insufficient for restoration of blood flow. These patients underwent additional revascularization with the second donor branch (35.7%). In all cases, we achieved significant quantitative improvement in CBF and volume of brain tissue with restored blood flow (ASPECTS scale). A single EICMA was followed by increase in CBF and areas of restored blood flow by almost 2 times (22.7±9.6 ml/100 g/min and 4.7±1.8 scores (ASPECTS) before surgery vs. 39.4±16.4 ml/100 g/min and 4.7±1.8 scores after EICMA). In the double EICMA group, these parameters increased by almost 3 times (18±3.1 ml/100 g/min and 3.8±0.9 scores before surgery vs. 57±11.4 ml/100 g/min and 7.7±1.5 scores after double EICMA). All patients had no complications. Neurological status improved immediately after surgery in 9 patients (33.3%), stable postoperative period was observed in 12 cases (44.4%). Six (22.2%) patients had transient neurological deficit associated with hyperperfusion syndrome that regressed within a few days after surgery. There were no persistent ischemic complications. CONCLUSION: Intraoperative ASL perfusion is an effective and informative tool for determining the degree of restoration of blood flow. We can timely adjust surgical strategy, determine the indications or contraindications for additional revascularization and exclude early ischemic complications using this method.

[Metastatic brain lesion following gastrointestinal stromal tumor of the stomach complicated by coma.( A case report and literature review)]. / Metastaticheskoe porazhenie golovnogo mozga gastrointestinal'noi stromal'noi opukhol'yu zheludka, oslozhnivsheesya razvitiem komatoznogo sostoyaniya. (Opisanie sluchaya i obzor literatury).

The authors present an extremely rare case of metastatic brain lesion in a patient with gastrointestinal stromal tumor of the stomach. There are literature data on 23 cases of metastatic lesions of the brain, skull and soft tissues of the head in similar patients. Atypical localization of metastases can lead to some diagnostic difficulties, unreasonable cancellation of chemotherapy and delayed surgical treatment. A feature of our observation was postoperative coma determined by the features of the underlying disease.

[Radiological biomarkers of brain gliomas]. / Radiologicheskie biomarkery gliom golovnogo mozga.

The most important objective of modern neuroimaging is comparison of data on genotype and phenotype of brain gliomas. Radiogenomics as a new branch of science is devoted to searching for such relationships based on MRI and PET/CT parameters. The 2021 WHO classification of tumors of the central nervous system poses the most important tasks for physicians in assessment of biological behavior of tumors and their response to combined treatment. The review demonstrates the possibilities and prospects of preoperative MRI and PET/CT with amino acids in assessing the genetic profile of brain gliomas.

[Spinal CSF-venous fistula: case report and literature review]. / Spinal'naya likvoro-venoznaya fistula kak prichina sindroma spontannoi vnutricherepnoi gipotenzii: sluchai iz praktiki i obzor literatury.

Syndrome of spontaneous intracranial hypotension is increasingly described in the literature as a multifactorial disease with impairment of the quality of life and risk of mortality. CSF-venous fistula as a cause of intracranial hypotension syndrome is extremely rare and requires complex diagnosis and timely surgical treatment. OBJECTIVE: We present a 55-year-old patient with acute spontaneous intracranial hypotension and spinal CSF-venous fistula. Literature data are also analyzed. RESULTS: Algorithm for diagnosis and efficacy of microsurgical resection of CSF-venous fistula is demonstrated. CONCLUSION: Intracranial hypotension following spinal fistula requires careful examination. Accurate understanding of pathophysiological and anatomical features of this disease is necessary to select an effective treatment method.

[Anaplastic pleomorphic xanthoastrocytoma - single-center analysis of 42 patients]. / Anaplasticheskaya pleomorfnaya ksantoastrotsitoma ­ analiz 42 nablyudenii iz odnoi kliniki.

Anaplastic pleomorphic xanthoastrocytoma is a rare tumor. There are still no objective data on the incidence of its diagnosis. OBJECTIVE: To study neuroimaging, morphological features of tumors, as well as factors affecting treatment and prognosis. MATERIAL AND METHODS: A retrospective study enrolled 42 patients operated on at the Burdenko Neurosurgery Center between 2003 and 2020. MR characteristics of anaplastic pleomorphic xanthoastrocytoma were analyzed. All patients underwent resection of tumor (total resection in 83.3% of cases). Redo surgeries were performed in 1/3 of patients. Mutational status of BRAF V600E was assessed in all patients. Adjuvant radio- and chemotherapy was performed in more than 80% of cases. Tyrosine kinase inhibitors were administered in 19% of cases. The follow-up period was 152 months (median 34 months). RESULTS: We found no pathognomonic MR signs of this disease. Indeed, anaplastic pleomorphic xanthoastrocytoma have the same signal characteristics as other malignant gliomas. The BRAF V600E mutation status was positive in 54.8% of cases. None patient had IDH-1 mutation. Mean Ki-67 index was 12.5%. The overall survival was 79 months (range 4-152). Seven (17%) patients are alive for more than 90 months. Only Ki-67 index and BRAF mutation significantly influenced the treatment prognosis and overall survival regardless the use of tyrosine kinase inhibitors. CONCLUSION: Such well-known factors for malignant glioma as patient age, total resection and adjuvant therapy did not significantly affect overall survival. Perhaps, searching for new molecular genetic features will reveal additional significant factors of prognosis in patients with anaplastic pleomorphic xanthoastrocytoma.

3D pCASL-perfusion in preoperative assessment of brain gliomas in large cohort of patients.

The aim of the study was to evaluate the role of pseudocontinuous arterial spin labeling perfusion (pCASL-perfusion) in preoperative assessment of cerebral glioma grades. The study group consisted of 253 patients, aged 7-78 years with supratentorial gliomas (65 low-grade gliomas (LGG), 188 high-grade gliomas (HGG)). We used 3D pCASL-perfusion for each patient in order to calculate the tumor blood flow (TBF). We obtained maximal tumor blood flow (maxTBF) in small regions of interest (30 ± 10 mm2) and then normalized absolute maximum tumor blood flow (nTBF) to that of the contralateral normal-appearing white matter of the centrum semiovale. MaxTBF and nTBF values significantly differed between HGG and LGG groups (p < 0.001), as well as between patient groups separated by the grades (grade II vs. grade III) (p < 0.001). Moreover, we performed ROC-analysis which demonstrated high sensitivity and specificity in differentiating between HGG and LGG. We found significant differences for maxTBF and nTBF between grade III and IV gliomas, however, ROC-analysis showed low sensitivity and specificity. We did not observe a significant difference in TBF for astrocytomas and oligodendrogliomas. Our study demonstrates that 3D pCASL-perfusion as an effective diagnostic tool for preoperative differentiation of glioma grades.

[Crossed aphasia in neurosurgical practice: case report and literature review]. / Perekrestnaya afaziya (Crossed aphasia) v neirokhirurgicheskoi praktike: opisanie sluchaev i obzor literatury.

BACKGROUND: Crossed aphasia in dexstral (CAD) is an extremely rare disorder. To date, about 200 cases have been described in the literature. MATERIAL AND METHODS: The authors report 4 cases of CAD. Luria's neuropsychological examination was carried out. Functional asymmetry in the arm was analyzed using the Annett questionnaire. MRI and intraoperative findings confirmed localization of lesion in the right hemisphere in all patients. RESULTS: A 59-year-old right-handed man developed frontotemporal aphasia after previous resection of right-sided glioblastoma of fronto-insular-temporal region. In a 31-year-old right-handed man, crossed aphasia occurred after extensive hemorrhage from arteriovenous malformation into the right frontotemporoparietal region. A 39-year-old right-handed man developed severe combined aphasia after resection of diffuse glioma of the right insular-temporal region. A 10-year-old right-handed boy developed aphasia with word forgetting after resection of a large tumor of the right temporal lobe. All patients had impaired dynamic praxis. Other cognitive functions were intact. CONCLUSION: The authors discuss possible combinations of functions in one hemisphere for both right-handers and left-handers and emphasize diverse types of functional asymmetries described in the literature. Different localizations of functions in right-handers and left-handers indicate that local zones with different methods of information processing (successive or simultaneous) can coexist in one hemisphere. Therefore, the functions requiring different processing of information (for example, speech with praxis or spatial functions) can develop in one hemisphere. Cognitive impairment depends not only on the type of functional asymmetry, but also on localization of lesion. Crossed aphasia in right-handers indicates the rarest normal type of functional brain asymmetry with localization of speech functions in the right hemisphere. Possible aphasia in right-handers following damage to homologues of speech zones in the right hemisphere can require additional examination of these patients.

3D pseudo-continuous arterial spin labeling-MRI (3D PCASL-MRI) in the differential diagnosis between glioblastomas and primary central nervous system lymphomas.

PURPOSE: The aim of the study was to compare the parameters of blood flow in glioblastomas and primary central nervous system lymphomas (PCNSLs), measured by pseudo-continuous arterial spin labeling MRI (3D PCASL), and to determine the informativeness of this method in the differential diagnosis between these lesions. METHODS: The study included MRI data of 139 patients with PCNSL (n = 21) and glioblastomas (n = 118), performed in the Burdenko Neurosurgical Center. No patients received chemotherapy, hormone therapy, or radiation therapy prior to MRI. On the 3D PCASL perfusion map, the absolute and normalized values of tumor blood flow were calculated in the glioblastoma and PCNSL groups (maxTBFmean and nTBF). RESULTS: MaxTBFmean and nTBF in the glioblastoma group were significantly higher than those in the PCNSL group: 168.9 ml/100 g/min versus 65.6 and 9.3 versus 3.7, respectively (p < 0.001). Arterial spin labeling perfusion had high sensitivity (86% for maxTBFmean, 95% for nTBF) and specificity (77% for maxTBFmean, 73% for nTBF) in the differential diagnosis between PCNSL and glioblastomas. Blood flow thresholds were 98.9 ml/100 g/min using absolute blood flow values and 6.1 using normalized values, AUC > 0.88. CONCLUSION: The inclusion of 3D PCASL in the standard MRI protocol can increase the specificity of the differential diagnosis between glioblastomas and PCNSL.

[Endoscopic endonasal reconstruction of skull base defects in the lateral recess of the sphenoid sinus: evaluation of computed tomograms for planning operations]. / Endoskopicheskaya endonazal'naya plastika defektov osnovaniya cherepa v oblasti lateral'nogo karmana klinovidnoi pazukhi: otsenka komp'yuternykh tomogramm dlya planirovaniya operatsii.

OBJECTIVE: Determine the influence of the anatomical features and sizes of the lateral pocket with a defect on the choice of surgical access and the quality of the performed plastics. MATERIAL AND METHODS: A retrospective analysis of computed tomograms of 38 patients who underwent surgical treatment at the Burdenko National Medical Research Center for Neurosurgery of the Ministry of Health of Russia about defects of the skull base in the area of the lateral pocket of the sphenoid sinus. The patients were divided into three groups depending on the approach used (the 1st group), the recurrence rate (the 2nd group), and the characteristics of intraoperative visualization of the defect (the 3rd group). RESULTS: There were no statistically significant differences in anatomical features in patients who underwent trans-pterygoid and transsphenoidal approaches, as well as in patients of the 2nd group. Patients of the 3rd group (with visualization features) showed statistically significant differences between the distance from the defect to the VR line (p=0.007). In patients with good visualization of the defect using direct optics, this distance was shorter than in patients in whom the defect was visualized with an angled endoscope. No other anatomical differences were noted. CONCLUSIONS: The anatomical features of the lateral pocket structure (type of pneumatization, size and volume) did not affect the choice of access to the defect and the frequency of recurrence. When comparing the approaches, it was noted that the trans-pterygoid access, providing direct visualization of defects, minimizes the risk of recurrence in the postoperative period. An objective anatomical indicator for choosing an access to the defects of the lateral pocket can be the distance from the defect to the VR line: at a distance of more than 0.7 cm, it is advisable to perform a trans-pterygoid approach; at a distance of less than 0.7 cm, it is possible to achieve direct visualization of the defect and perform high-quality plastic surgery with a transsphenoidal access.

[Radiosurgery for recurrent glioblastoma]. / Radiokhirurgicheskoe lechenie retsidivov glioblastom.

BACKGROUND: Despite the combined treatment in accordance with modern standards, recurrent glioblastoma usually occurs within several months after resection and causes low relapse-free and overall survival. One of the most effective methods for malignant glioma progression is repeated radiotherapy. Indications for this approach have expanded after introduction of stereotactic irradiation into routine clinical practice. OBJECTIVE: To evaluate the results of radiosurgery in patients with recurrent glioblastoma and to identify the factors determining its effectiveness. MATERIAL AND METHODS: Radiosurgery has been carried out in 168 patients with relapses of glioblastoma between 2005 and 2021. This study enrolled 88 patients with 180 foci of local and distant progression. Mean age of patients was 42.8±2.1 years (range 4-73). Mean period between diagnosis and repeated irradiation was 12.7 months. Mean volume of focus was 2.4 cm3, mean dose - 20 Gy. Median follow-up period after radiosurgery was 11.2 months. RESULTS: Repeated irradiation with correction of systemic therapy improved progression-free survival and overall survival with insignificant radiation-induced toxicity. Annual overall survival was 62.2%, median of overall survival after radiosurgery - 15.1 months. Significant factors of local control were marginal dose of at least 18 Gy and distant relapse. Median of progression-free survival in the group of distant progression of glioblastoma was only 3.6 months vs. 9.1 months in patients with local recurrence. CONCLUSION: Repeated irradiation in radiosurgery mode with a dose of 18 Gy and higher is an effective option for local treatment increasing progression-free and overall survival in patients with progression of glioblastoma.

[Conduction aphasia in patients with glioma in the left hemisphere]. / Provodnikovaya afaziya u bol'nykh s gliomami levogo polushariya.

Background. According to Wernicke-Geschwind model, conduction aphasia following arcuate tract lesion was canonized as primary disorder of repetition in relatively intact speech. OBJECTIVE: Syndromic analysis of speech and writing disorders in patients with arcuate tract lesion using the method by A.R. Luria and their comparison with well-known types of aphasia. MATERIAL AND METHODS: Clinical and neuropsychological survey was performed in 14 patients with gliomas who underwent surgical treatment at the Burdenko Neurosurgical Center (10 gliomas of the frontal lobe and 4 tumors of the temporal lobe). All patients underwent MRI, HARDI MRI tractography and A.R. Luria's neuropsychological examination prior to surgery and after 5-6 postoperative days. Thirteen patients underwent awake craniotomy, 3 of them were examined one year after surgery. RESULTS: In all patients, the tumor was localized near arcuate tract and its infiltration was noted. No intraoperative damage to the tract was ever noted according to speech monitoring data. However, postoperative edema followed by infiltration and dislocation of the tract (in all patients), as well as local ischemia in 4 patients were observed. After resection of prefrontal and premotor gliomas, aphasia included frontal (perseveration) and temporal components (disorders of naming, auditory-speech memory). Unusual verbal paraphrases were noted. We also observed severe violation of writing (temporal type) even if spontaneous speech and repetition were preserved. In case of resection of deep posterior temporal gliomas, speech disorders included signs of frontal lobe lesion (perseveration) and writing disorders. Similar motor abnormalities were identified in writing. CONCLUSION: Arcuate tract lesion can result speech and writing disorders as signs of damage to certain cortical speech zones (frontal and temporal lobe). Violations of repetition were not predominant in any case. At the same time, interruption of connection between motor and auditory image of the word could be revealed in writing.

[Magnetic resonance relaxometry in high-grade glioma subregion assessment - neuroimaging and morphological correlates]. / Magnitno-rezonansnaya relaksometriya v otsenke subregionov gliom golovnogo mozga vysokoi stepeni zlokachestvennosti ­ neirovizualizatsionnye i morfologicheskie korrelyaty.

OBJECTIVE: To analyze the differences of high-grade glioma subregions using magnetic resonance relaxometry with compilation of images (MAGiC) and arterial spin labeling (ASL), as well as to compare quantitative measurements of these techniques with morphological data. MATERIAL AND METHODS: The study enrolled 35 patients with newly diagnosed supratentorial gliomas (23 - grade IV, 12 - grade III). We measured relaxometric values (T1, T2, proton density), tumor blood flow (TBF) in glioma subregions and normal-appearing brain matter. Neuronavigation was intraoperatively used to obtain tissue samples from active tumor growth zone, perifocal infiltrative edema zone and adjacent brain matter along surgical approach. RESULTS: ASL perfusion revealed higher tumor blood flow (TBF) in active tumor growth region compared to perifocal infiltrative edema zone (p<0.01). Relaxometric values (T1, T2, proton density) in perifocal zone were higher (p<0.01) compared to adjacent intact white matter along surgical approach. However, there were no differences in TBF between these zones. Proton density in tumor-adjacent intact white matter was higher (p<0.01) compared to normal-appearing white matter in ipsilateral hemisphere. There was inverse correlation between T2 and TBF in active tumor growth zone (Spearman rank R= -0.58; p=0.0016). We found inverse correlation between T2 and Ki67 proliferative index and direct correlation between TBF and Ki67 in this zone. Nevertheless, these relationships were insignificant after multiple test adjustment. CONCLUSION: Our study advocates for complementary power of ASL perfusion and MR relaxometry in assessment of high-grade brain glioma subregions. More malignant tumor zones tend to have higher TBF and shorter T2. Further investigation is needed to prove the capability of MAGiC to reveal foci of increased relaxometric values in tumor-adjacent normal-appearing white matter.

[Anaplastic astrocytoma and anaplastic oligodendroglioma of the brain: current state of the problem]. / Anaplasticheskie astrotsitomy i anaplasticheskie oligodendrogliomy golovnogo mozga: sovremennoe sostoyanie problemy.

This review is devoted to the problem of anaplastic cerebral gliomas. The authors consider classification, neuroimaging of these tumors including comparison of magnetic resonance imaging and positron emission tomography data. Clinical manifestations of anaplastic gliomas, issues of their histological and molecular genetic classification are discussed. Moreover, the authors compare the data of neuroimaging and genetic examinations of tumors. Other issues are multicomponent treatment and prognosis in patients with anaplastic glioma of the brain.

[Dynamic11C-methionine PET/CT in differential diagnosis of brain gliomas]. / Dinamicheskaya PET/KT s 11S-metioninom v differentsial'noi diagnostike glial'nykh opukholei golovnogo mozga.

OBJECTIVE: To evaluate the possibilities of dynamic preoperative 11C-methionine (MET) PET/CT in differential diagnosis of various types of brain gliomas in adults. MATERIAL AND METHODS: The study included 74 patients aged 48±14 years with supratentorial gliomas: Grade IV - glioblastoma (GB, n=33), Grade III - anaplastic oligodendroglioma (AOD, n=10) and anaplastic astrocytoma (AA, n=12), Grade II - diffuse astrocytoma (DA, n=13) and oligodendroglioma (OD, n=6). All patients underwent standard MRI and dynamic MET PET/CT within 20 minutes after intravenous injection of radiopharmaceutical. Then, we compared MRI and PET/CT data and comprehensively analyzed the early stages of time-activity curve using 2 parameters: the first pass peak (FPP) and the first peak of maximum uptake (Pmax). RESULTS: We have significantly distinguished high-grade tumors (GB and AA+AOD) and certain benign gliomas (DA and OD) (p<0.05). AUC was over 0.7 and 0.8 for FPP and Pmax in differential diagnosis of various gliomas, respectively. We found that difficulties in differential diagnosis of gliomas arise mainly if oligodendrogliomas are included in the control group. CONCLUSION: Dynamic PET/CT with analysis of FPP and Pmax increases specificity of differential diagnosis of various gliomas compared to standard static imaging. These data are valuable for choice of optimal treatment strategy, as well as fundamental research of metabolic processes and vascularization of various tumors.

[Phosphorus MR spectroscopy and 18F-FDG PET/CT in the study of energy metabolism of glial tumors]. / Fosfornaya MR-spektroskopiya i PET/KT s 18F-FDG v izuchenii energeticheskogo metabolizma glial'nykh opukholei.

OBJECTIVE: To study energy metabolism in glial tumors using dynamic MR spectroscopy and 18F-FDG PET/CT. MATERIAL AND METHODS: The study included 19 patients (9 women and 10 men) with newly diagnosed supratentorial glial tumors WHO Grade I-IV (diffuse astrocytoma - 4 cases, oligodendroglioma - 4 cases, anaplastic astrocytoma - 5 cases, glioblastoma - 6 cases). All patients underwent examination and surgical treatment at the Burdenko Neurosurgery Center. Dynamic MR spectroscopy and 18F-FDG PET/CT were applied in each patient. RESULTS: We found multiple correlations between the ratio of bioorganic phosphate peaks and parameters of glucose uptake by tumor tissue. These relationships were more significant in patients with high-grade tumors: positive significant correlation between SUVtumor and PME/PCr ratio (RS=0.75, p=0.01), T/Nmix and ßATP/Pi ratio (Rs=0.76, p=0.02), SUVpeaktumor and aATP/Pi ratio (RS=0.77, p=0.008). Moreover, there were negative correlations between SUVtumor and PCr/bATP ratio (RS= -0.66, p=0.05), T/Nmix and PDE/bATP ratio (RS= -0.83, p=0.006), SUVpeaktumor and PDE/aATP ratio (RS= -0.76, p=0.009). CONCLUSION: High-grade gliomas were characterized by higher glucose consumption, ATP release (intensification of energy metabolism) and faster cell membrane synthesis. These processes indicate enhanced proliferation of tumor cells (intensification of plastic metabolism).

Feasibility of generalised diffusion kurtosis imaging approach for brain glioma grading.

PURPOSE: An accurate differentiation of brain glioma grade constitutes an important clinical issue. Powerful non-invasive approach based on diffusion MRI has already demonstrated its feasibility in glioma grade stratification. However, the conventional diffusion tensor (DTI) and kurtosis imaging (DKI) demonstrated moderate sensitivity and performance in glioma grading. In the present work, we apply generalised DKI (gDKI) approach in order to assess its diagnostic accuracy and potential application in glioma grading. METHODS: Diffusion scalar metrics were obtained from 50 patients with different glioma grades confirmed by histological tests following biopsy or surgery. All patients were divided into two groups with low- and high-grade gliomas as grade II versus grades III and IV, respectively. For a comparison, trained radiologists segmented the brain tissue into three regions with solid tumour, oedema, and normal appearing white matter. For each region, we estimated the conventional and gDKI metrics including DTI maps. RESULTS: We found high correlations between DKI and gDKI metrics in high-grade glioma. Further, gDKI metrics enabled introduction of a complementary measure for glioma differentiation based on correlations between the conventional and generalised approaches. Both conventional and generalised DKI metrics showed quantitative maps of tumour heterogeneity and oedema behaviour. gDKI approach demonstrated largely similar sensitivity and specificity in low-high glioma differentiation as in the case of conventional DKI method. CONCLUSION: The generalised diffusion kurtosis imaging enables differentiation of low- and high-grade gliomas at the same level as the conventional DKI. Additionally, gDKI exhibited higher sensitivity to tumour heterogeneity and tissue contrast between tumour and healthy tissue and, thus, may contribute as a complementary source of information on tumour differentiation.

[Intracellular pH measurement in glioblastoma cells: the possibilities of phosphorus-31 MR spectroscopy]. / Izmerenie vnutrikletochnogo vodorodnogo pokazatelya glioblastom: vozmozhnosti fosfornoi magnitno-rezonansnoi spektroskopii.

OBJECTIVE: To analyze intracellular pH measurement with phosphorus-31 MR spectroscopy in glioblastoma cells and to compare these data with intracellular pH in healthy volunteers. MATERIAL AND METHODS: There were 10 patients aged 41 - 67 years with supratentorial glioblastomas. Intracellular pH in glioblastoma cells was compared with pH in healthy persons. RESULTS: We found a tendency to increased intracellular pH in glioblastoma cells in comparison with pH in intact brain tissue. CONCLUSION: Intracellular pH in brain tissue can be used as a potential marker of early abnormalities which could not be detected by conventional MRI. Moreover, these data may be valuable to estimate the efficacy of chemotherapy. The study was supported by Russian Science Foundation (grant No. 18-15-00337).

[Orbital venous varices: modern diagnostic methods and differential diagnosis]. / Orbital'nyi venoznyi varikoz: sovremennye metody diagnostiki i differentsial'nyi diagnoz.

OBJECTIVE: To study the possibility of the modern CT and MRI methods in diagnostics of the orbital venous varices (OVV), discover the special characteristics of these lesions concerning their hemodynamic and differential diagnosis with other orbital lesions. MATERIAL AND METHODS: In the period from 2012 to 2019 ten patients with OVV were evaluated. Four of them were men, three - women and three - children (boys aged 7, 10, and 12 years). Age of the patients varied from 7 to 75 years old (mediana - 34).CT was performed on 9 patients using low dose protocol with injecting the contrast in standard position (supine) and in the prone position. CT-angiography was performed on 3 patients and CT-perfusion - 5 patients which allowed the assessment of the blood supply and quantitative lesions hemodynamic by calculating blood flow (BFOVV), blood volume (BVOVV) and mean transit time (MTTOVV).MRI with contrast injection and Fat Sat technology was performed on 9 patients, 3 of them were both in the supine and prone positions. 4 patients were evaluated by bolus MR-angiography (TRICKS). RESULTS: The majority of the OVV was localized in the medial compartments and apex of the orbit. Left sided lesions were found in 6 cases, right - 3. One patient had both sided OVV. In one of the cases in 10-year-old child, we revealed malformation of the Galen vein associated with bilateral varicose enlargement of the intraorbital veins (secondary OVV).In CT studies all of the lesions enhanced after the contrast injection. When the patients were study in the prone position, all lesions were enlarging; which lead to the diagnosis of OVV. CT-angiography (venous blood flow) proved vascular nature of the lesions. While studying the quantitative lesion hemodynamic by the CT perfusion technology, it was discovered, that OVV tend to have high blood volume (BVOVV=19.61±3.23(ml/100g) and high blood flow (BFOVV= 60.87±8.11) and the prolongation of mean transit time (MTTOVV=19.23±3.07). Normal parameters measured in white matter were CBVN=1.37±0.69(ml/100g), CBFN=38.4±4.31(ml/100g/min), MTTN=2.89±0.44s.In MRI studies all the lesions had iso-hypointense MR-signal on T1- and hyperintense on T2-images. The pattern of contrast enhancement was inhomogeneous, however reaching homogeneity after some time. TRICKS MR-angiography was more sensitive than CT-angiography (venous phase). Moreover, the absence of radiation exposition was an additional advantage of the MR-venography. CONCLUSION: Diagnosis of orbital vascular pathology requires an understanding of the classification of vascular lesions, the integration of the patient's medical history with epidemiological data, as well as a through analysis of the results of instrumental diagnostic methods. CT or MRI, including scanning in the prone position, as well as minimally invasive CT- and MR-TRICKS-angiography and ophthalmological studies of the patient, determine a comprehensive approach to the diagnosis and selection of adequate treatment for orbital venous varices.In the differential diagnosis of OVV with other neoplasms of the orbit, we recommend CT-perfusion study with determine the quantitative characteristics of its hemodynamics.