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.

[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.

[Assessment of brain neural pathways in diffuse axonal injuries using diffusion-tensor magnetic resonance tomography].

BACKGROUND: Aim of this study was to assess the role of diffusion-tensor magnetic resonance imaging (DT-MRI) in diagnosis and prognosis in severe diffuse axonal injury (DAI). MATERIALS AND METHODS: The studies using 1.5 Tesla MR tomograph were performed on 2nd-17th days after injury in 22 patients with DAI and in 8 healthy volunteers. All patients were comatose in acute period (GCS 4-8), 11 had hemiparesis and in 4 had tetraparesis. Outcomes were evaluated after 6 months using GOS. Indices of diffusion coefficient (DCI) and fraction anisotropy (FA) were assessed bilaterally: in genu and splenium of corpus callosum, posterior limb of internal capsule (PLIC), cerebral peduncles, at the level of pons (along corticospinal tracts (CST). RESULTS: Significant decrease of FA (p < 0.05) along CST bilaterally was found in 7 patients without movement disorders comparing to analogous indices in the control group. Also statistically significant decrease of FA at the level of PLIC and cerebral peduncles was observed on the contralateral side in patients with hemiparesis (p < 0.01). In patients with tetraparesis FA was significantly decreased along CST bilaterally (p < 0.00001). Indices of FA in corpus callosum and along pyramidal tracts significantly correlated with outcomes in patients examined on 10th-17th day after injury (p < 0.01). In the whole group of patients mean indices of FA and DCI in the splenium of corpus callosum were significantly decreased (p < 0.01 and p < 0.05, respectively). 3D reconstruction of CST allowed to discover asymmetry of CST in 3 of 9 patients with hemiparesis on 1st-9th day after injury and in all 6 patients examined on 10th-17th day. CONCLUSION: Indices of FA reflect the degree of integrity of white matter pathways with significant accuracy. Application of DT-MRI allows to reveal quantitative and qualitative alterations in white matter tracts and to assess their clinical and prognostic value in DAI.

[Dynamic assessment of corpus callosum and corticospinal tracts structure using diffusion-tensor MRI in diffuse axonal injury].

BACKGROUND: Diffuse axonal injury (DAI) causes neurodegenerative processes in brain which can last weeks and months after traumatic brain injury. Aim of this study was to assess structural changes of corpus callosum and corticospinal tracts in dynamics using diffusion-tensor magnetic resonance imaging (DT-MRI) in severe DAI. MATERIALS AND METHODS: 14 patients with severe DAI (GCS < or = 8 in acute period) were examined using DT-MRI. In 12 cases 1.5 Tesla device was used, in 2-3 Tesla tomography was applied. Initial studies were performed on 3rd-17th days after injury and control studies were done between 3 weeks and 33 months after injury. Outcomes were assessed using GOS 6 months after injury and later. RESULTS: MR-tractography demonstrated almost absolutely absent visualization of ascending fibers of corpus callosum 3-20 weeks after brain injury in 5 patients with poor outcomes (severe disability and persistent vegetative state). Raized asymmetry of corticospinal tracts was associated with hemiparesis or quadriparesis in the same patients. In 6 patients with severe disability partial loss and thinning of corpus callosum fibers were observed. In 2 patients with good recovery and moderate disability repeated studies showed no severe changes in structure of corpus callosum. CONCLUSION: DT-MRI presents new data about structural changes of white matter tracts in traumatic brain injury.