[Perifocal edema and glymphatic system dysfunction: quantitative assessment based on diffusion tensor magnetic resonance imaging]. / Peritumoroznyi otek i disfunktsiya glimfaticheskoi sistemy golovnogo mozga: kolichestvennaya otsenka na osnove diffuzionno-tenzornoi MRT.

BACKGROUND: Pathogenesis of peritumoral cerebral edema is unclear and potentially associated with glymphatic system dysfunction. Diffusion tensor MRI (DT-MRI) with analysis of ALPS (Analysis along the Perivascular Space) index may be valuable for assessment of edema. This approach visualizes fluid flow along perivascular spaces of deep cerebral veins. OBJECTIVE: To assess glymphatic system function in supratentorial tumors and healthy volunteers using DT-MRI. MATERIAL AND METHODS: There were 52 patients (59% men) aged 43 (28-64) years with supratentorial tumors (meningioma - 20, grade 3-4 glioma - 15, metastases - 9, lymphoma - 8). Tumors and perifocal edema did not involve deep cerebral veins. The control group included 6 healthy volunteers aged 34-66 years. MRI protocol (Signa HDxt, 3 T) contained standard T1, T2, T2FLAIR, DWI and post-contrast T1 (3D BRAVO). DT-MRI had the following parameters: TR=10 000 ms, TEmin=102 ms, FOV=240 mm, isotropic voxel size 3×3×3 mm3, 60 directions of diffusion gradients. Measurements were carried out at b-factor 0 and 1000 s/mm2. Analysis was carried out in the ReadyView software. RESULTS: Right- and left-sided ALPS indices were similar in the control group (p=0.917). Perifocal edema (regardless of histological type of tumor) in the ipsilateral hemisphere was accompanied by significantly lower ALPS index (p<0.005), while these values in contralateral (intact) hemisphere were similar in both groups (p=0.7). CONCLUSION: We found significantly lower ALPS index in deep parts of the affected hemisphere in patients with perifocal edema. These data can indicate the role of glymphatic system dysfunction in pathogenesis of this pathology.

[Factors influencing peritumoral edema in meningiomas: CT- and MRI-based quantitative assessment]. / Peritumoroznyi otek pri meningiomakh i faktory, vliyayushchie na ego formirovanie: kolichestvennaya otsenka na osnove KT i MRT.

Background. Meningiomas may be accompanied by peritumoral edema. Incidence and pathogenesis of edema are nor clearly established. Prevalence and severity of edema vary significantly in patients with meningiomas similar in various parameters. OBJECTIVE: To assess peritumoral edema in intracranial meningiomas and factors influencing incidence and severity of this process. MATERIAL AND METHODS: There were 126 patients (69% women) aged 19-76 years (median 53), who were diagnosed with 142 meningiomas. Patients underwent surgery (n=111) and radiotherapy (n=15) in 2016-2018. The MRI protocol included T1, T2, T2-FLAIR, DWI and post-contrast T1-weighted images in three projections, diffusion tensor MRI in 27 cases and MR spectroscopy in 21 patients. RESULTS: Peritumoral edema was detected in 46% (n=66) of cases including 21 (31%) patients with severe edema. The ALPS index was 1.510±0.1931 in meningiomas without edema and 1.308±0.19 in those with edema (p=0.014). There was positive correlation between edema, dimensions and uneven contours of meningioma, as well as negative correlation with CSF cleft sign. Blood flow velocity was higher in atypical and anaplastic meningiomas with edema (p=0.03). Other signs (localization, histological variant, malignancy grade, characteristics of MR signal, peaks of the main metabolites, diffusion and perfusion parameters of tumor) did not significantly affect peritumoral edema in patients with meningiomas (p>0.05). CONCLUSION: Diffusion tensor tomography with ALPS index revealed significant effect of glymphatic system dysfunction on peritumoral edema. Large meningioma with uneven contours increased the risk of peritumoral edema, while CSF cleft sign reduced this risk. Other factors did not affect cerebral edema in meningiomas.

[Machine learning for resting state fMRI-based preoperative mapping: comparison with task-based fMRI and direct cortical stimulation]. / Primenenie mashinnogo obucheniya dlya predoperatsionnogo kartirovaniya po dannym funktsional'noi magnitno-rezonansnoi tomografii pokoya: sravnenie so stimul-zavisimoi funktsional'noi magnitno-rezonansnoi tomografiei i pryamoi elektricheskoi stimulyatsiei kory.

OBJECTIVE: To develop a system for preoperative prediction of individual activations of motor and speech areas in patients with brain gliomas using resting state fMRI (rsfMRI), task-based fMRI (tb-fMRI), direct cortical stimulation and machine learning methods. MATERIAL AND METHODS: Thirty-three patients with gliomas (19 females and 14 males aged 19 - 540) underwent DCS-assisted resection of tumor (19 ones with lesion of motor zones and 14 patients with lesions of speech areas). Awake craniotomy was performed in 14 cases. Preoperative mapping was performed according to special MRI protocol (T1, tb-fMRI, rs-fMRI).Machine learning system was built on open source data from The Human Connectome Project. MR data of 200 healthy subjects from this database were used for system pre-training. Further, this system was trained on the data of our patients with gliomas. RESULTS: In DCS, we obtained 332 stimulations including 173 with positive response. According to comparison of functional activations between rs-fMRI and tb-fMRI, there were more positive DCS responses predicted by rs-fMRI (132 vs 112). Non-response stimulation sites (negative) prevailed in tb-fMRI activations (69 vs 44). CONCLUSION: The developed method with machine learning based on resting state fMRI showed greater sensitivity compared to classical task-based fMRI after verification with DCS: 0.72 versus 0.66 (p<0.05) for identifying the speech zones and 0.79 versus 0.62 (p<0.05) for motor areas.

[Comparison of resting state and task-based functional MRI in preoperative mapping in patients with brain gliomas]. / Sravnenie funktsional'noi magnitno-rezonansnoi tomografii v sostoyanii pokoya i stimul-zavisimoi funktsional'noi magnitno-rezonansnoi tomografii v predoperatsionnom kartirovanii u patsientov s gliomami golovnogo mozga.

OBJECTIVE: To analyze and compare the results of cerebral cortex mapping with task-based (tb-fMRI) and resting-state functional MRI in patients with glioma of eloquent cortical areas. MATERIAL AND METHODS: There were 55 patients (24 men and 31 women aged 24 - 74 years, median 39) with glial tumors. In 26 patients, the tumor was located in motor areas. Twenty-nine patients had lesions of Broca and Wernicke's areas. All patients underwent preoperative tb-fMRI and rs-fMRI. Then, resection of tumor was carried out in all cases. RESULTS: Comparison of fMRI and rs-fMRI activation maps was assessed by calculating the Dice coefficient for inclusive speech and motor cortex masks and exclusive masks without brainstem, cerebellum, subcortical nuclei. Inclusive Dice coefficient for motor cortex ranged from 0.11 to 0.50, for speech cortex - from 0.006 to 0.240 (p<0.05). In case of exclusive masks, this value ranged from 0.15 to 0.55 for motor cortex and from 0.004 to 0.205 for speech cortex (p<0.05). CONCLUSION: When comparing the results of cortical mapping in patients with glial tumors, the use of hemispheric exclusive and inclusive masks did not significantly increase activation maps matching. Probably, low degree of correspondence was associated with different genesis of activations, as well as with high variability of speech cortex.

[Periventricular changes following hydrocephalus: quantitative MR-based assessment of tissue characteristics]. / Periventrikulyarnye izmeneniya pri gidrotsefalii: kolichestvennaya otsenka tkanevykh kharakteristik metodom magnitno-rezonansnoi tomografii.

OBJECTIVE: To study tissue characteristics of periventricular white matter in patients with open hydrocephalus using DWI MRI and their correlations with CSF flow parameters. MATERIAL AND METHODS: MRI was performed in 55 patients (35 women and 20 men) with open normal pressure hydrocephalus, as well as 16 patients with malignant occlusive hydrocephalus and interstitial edema (control group). We determined the correlations between severity of hydrocephalus, periventricular lesions and CSF flow parameters considering MR data. Dimensions of ventricular system were assessed using the Evans' index, periventricular changes - using visual four-level scale with calculation of apparent diffusion coefficient (ADC) and fractional anisotropy coefficient (FA). RESULTS: Among patients with open hydrocephalus, ACD range for periventricular white matter was 1.57±0.15·10-3 mm2/s in subgroup of patients without periventricular changes (n=29) and 1.62±0.11×10-3 mm2/s in patients with periventricular changes (n=26). In the control group, mean ADC was 1.76±0.18·10-3 mm2/s (p<0.05). In patients with open hydrocephalus, FA coefficient in the areas of periventricular changes was 0.70-0.80, in case of occlusive hydrocephalus - 0.68-0.82. There was a significant relationship between the Evans' index and CSF pulsation velocity amplitude, Evans' index and stroke volume, Evans' index and cerebral aqueduct cross-sectional area in patients with open hydrocephalus. Periventricular changes were pronounced in patients with open hydrocephalus and Evans' index > 0.4 (p<0.05). CONCLUSION: According to MR data, periventricular changes in patients with open hydrocephalus differ from true periventricular interstitial edema following occlusive hydrocephalus. Severity of periventricular changes in patients with open hydrocephalus depends on patient age and width of the ventricles, but does not correlate with CSF flow parameters. In our opinion, periventricular changes are associated with dysfunction of glymphatic system. Further research is required to study the functioning of glymphatic system and related processes.

[Surgical treatment of drug-resistant epilepsy following hippocampal sclerosis]. / Khirurgicheskoe lechenie farmakorezistentnoi epilepsii pri skleroze gippokampa.

Surgery is an effective approach for drug-resistant temporal lobe epilepsy following hippocampal sclerosis. There is still no clear and unanimous opinion about advantages and disadvantages of certain surgical technique. MATERIAL AND METHODS: There were 103 surgical interventions in 101 patients. Females prevailed (1.45:1). Age of patients ranged from 16 to 56 years (median 28). Anteromedial temporal lobectomy and selective amygdaloghippocampectomy were performed in 49 (47.6%) and 54 (52.4%) patients, respectively. In the latter group, 30 patients were operated via a 14-mm burr hole-subtemporal approach. Postoperative outcomes were assessed using the Engel grading system. The follow-up period ranged from 2 to 8 years (median 4 years). RESULTS: By the 2nd year, Engel class I was observed in 74 (72%) patients, Engel II, III and IV - in 20 (19.4%), 6 (5.8%) and 3 (2.9%) patients, respectively. Engel class I was achieved after anteromedial temporal lobectomy in 68% of cases, selective amygdaloghippocampectomy via standard approaches in 75% of cases, amygdaloghippocampectomy via subtemporal burr hole approach - in 80% of cases. Neurocognitive impairments after anteromedial lobectomy and selective amygdaloghippocampectomy were similar. At the same time, mental disorders de novo prevailed in the group of anteromedial lobectomy (p<0.05). There were no severe visual field disorders after subtemporal burr-hole access. In other cases, these disorders occurred in 36.2% of patients (p<0.05). There were 8 (7.8%) postoperative complications: 5 (10.2%) - after anterior temporal lobectomy, 3 (5.5%) - after selective surgeries via standard approaches. There were no complications after burr-hole surgery. CONCLUSION: Selective amygdaloghippocampectomy is not inferior to anteromedial lobectomy. Moreover, this procedure is associated with a lower risk of complications and adverse events.

[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.

[Resting-state fMRI in preoperative non-invasive mapping in patients with left hemisphere glioma]. / Funktsional'naya magnitno-rezonansnaya tomografiya sostoyaniya pokoya v predoperatsionnom neinvazivnom kartirovanii u patsientov s gliomami levogo polushariya golovnogo mozga.

Maximum resection and preservation of neurological function are main principles in surgery of brain tumors, especially glial neoplasms with diffuse growth. Therefore, exact localizing of eloquent brain areas is an important component in surgical planning ensuring optimal resection with minimal postoperative neurological deficit. Functional MRI is used to localize eloquent brain areas adjacent to the tumor. This paper is an initial stage in analysis of resting-state fMRI in assessment of functional changes of neuronal activity caused by brain gliomas of different localization. We report two patients with glial tumors localized within the precentral gyrus of the left hemisphere and near speech area. Considering data of task-based and resting-state fMRI, as well as direct cortical stimulation, we propose a methodology for assessing the overlap of activations obtained by these methods.