• This study tested the validity of noninvasive electrical conductivity measurements by MRI. • This study also evaluated the electrical conductivity characteristics of diffuse glioma. • Gliomas have higher electrical conductivity values than the normal brain parenchyma. • Noninvasive electrical conductivity measurement can be helpful for better characterisation of glioma.

Sonodynamic therapy is expected to be a novel therapeutic strategy for malignant gliomas. The titanium dioxide (TiO 2 ) nanoparticle, a photosensitizer, can be activated by ultrasound. In this study, by using water-dispersed TiO 2 nanoparticles, an in vitro comparison was made between the photodynamic and sonodynamic damages on U251human glioblastoma cell lines. Water-dispersed TiO 2 nanoparticles were constructed by the adsorption of chemically modified polyethylene glycole (PEG) on the TiO 2 surface (TiO 2 /PEG). To evaluate cytotoxicity, U251 monolayer cells were incubated in culture medium including 100 μg/ml of TiO 2 /PEG for three hours and subsequently irradiated by

).q RSNA, 2015 Purpose:To develop and independently validate prognostic imaging biomarkers for predicting survival in patients with glioblastoma on the basis of multiregion quantitative image analysis. Materials and Methods:This retrospective study was approved by the local institutional review board, and informed consent was waived. A total of 79 patients from two independent cohorts were included. The discovery and validation cohorts consisted of 46 and 33 patients with glioblastoma from the Cancer Imaging Archive (TCIA) and the local institution, respectively. Preoperative T1-weighted contrast material-enhanced and T2-weighted fluid-attenuation inversion recovery magnetic resonance (MR) images were analyzed. For each patient, we semiautomatically delineated the tumor and performed automated intratumor segmentation, dividing the tumor into spatially distinct subregions that demonstrate coherent intensity patterns across multiparametric MR imaging. Within each subregion and for the entire tumor, we extracted quantitative imaging features, including those that fully capture the differential contrast of multimodality MR imaging. A multivariate sparse Cox regression model was trained by using TCIA data and tested on the validation cohort. Results:The optimal prognostic model identified five imaging biomarkers that quantified tumor surface area and intensity distributions of the tumor and its subregions. In the validation cohort, our prognostic model achieved a concordance index of 0.67 and significant stratification of overall survival by using the log-rank test (P = .018), which outperformed conventional prognostic factors, such as age (concordance index, 0.57; P = .389) and tumor volume (concordance index, 0.59; P = .409). Conclusion:The multiregion analysis presented here establishes a general strategy to effectively characterize intratumor heterogeneity manifested at multimodality imaging and has the potential to reveal useful prognostic imaging biomarkers in glioblastoma.q RSNA, 2015

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor and its prognosis is significantly poorer than those of less malignant gliomas.Pathologically, necrosis is one of the most important characteristics that differentiate GBM from lower grade gliomas; therefore, we hypothesized that 18 F fluoromisonidazole (FMISO), a radiotracer for hypoxia imaging, accumulates in GBM but not in lower grade gliomas. We aimed to evaluate the diagnostic value of FMISO PET for the differential diagnosis of GBM from lower grade gliomas. Methods: This prospective study included 23 patients with pathologically confirmed gliomas. All the patients underwent FMISO PET and FDG PET within a week. FMISO images were acquired 4 hours after intravenous administration of 400 MBq of FMISO. Tracer uptake in the tumor was visually assessed. Lesion-to-normal tissue ratios and FMISO uptake volume were calculated. Results: Thirteen of the 23 glioma patients were diagnosed as having GBM (grade IV glioma in WHO classification 2007), and the others were diagnosed as having non-GBM (5 grade III and 4 grade II). In visual assessment, all the GBM patients showed FMISO uptake in the tumor greater than that in the surrounding brain tissues, whereas all the non-GBM patients showed FMISO uptake in the tumor equal to that in the surrounding brain tissues (p<0.001). One GBM patient was excluded 2 from FDG PET study because of hyperglycemia. All the GBM patients and 3 of the 9 (33 %) non-GBM patients showed FDG uptake greater than or equal to that in the gray matter. The sensitivity and specificity for diagnosing GBM were 100 % and 100 % for FMISO, and 100 % and 66 % for FDG, respectively. The lesion-to-cerebellum ratio of FMISO uptake was higher in GBM patients (2.74±0.60, range: 1.71 -3.81) than in non-GBM patients (1.22±0.06, range: 1.09 -1.29, p<0.001) with no overlap between the groups. The lesion-to-gray matter ratio of FDG was also higher in GBM patients (1.46±0.75, range: 0.91 -3.79) than in non-GBM patients (1.07±0.62, range: 0.66 -2.95, p<0.05); however, overlap of the ranges did not allow clear differentiation between GBM and non-GBM. Uptake volume of FMISO was larger in GBM (27.18±10.46 %, range: 14.02 -46.67 %) than in non-GBM (6.07±2.50 %, range: 2.12 -9.22 %, p<0.001). Conclusion: These preliminary data suggest that FMISO PET may distinguish GBM from lower grade gliomas.

Titanium dioxide (TiO(2)) is thought to be a photocatalytic agent excited by UV light. Our aim was to investigate the photocatalytic antitumor effect of water-dispersed TiO(2) nanoparticles on C6 rat glioma cells and to evaluate the treatment responses by the spheroid models. Water-dispersed TiO(2) nanoparticles were constructed by the adsorption of chemical modified polyethylene glycol (PEG) on the TiO(2) surface (TiO(2)/PEG). Each monolayer and spheroid of C6 cells was coincubated with various concentrations of TiO(2)/PEG and subsequently irradiated with UV light. Damage of the cells and spheroids was evaluated sequentially by staining with the fluorescent dyes. The cytotoxic effect was correlated with the concentration of TiO(2)/PEG and the energy dose of UV irradiation. More than 90% of cells were killed after 13.5 J cm(-2) of UV irradiation in the presence of 500 microg mL(-1) TiO(2)/PEG. The irradiated spheroids in the presence of TiO(2)/PEG showed growth suppression compared with control groups. In TiO(2)/PEG-treated spheroids, the number of Annexin V-FITC-stained cells gradually increased during the first 6 h, and subsequently propidium iodide-stained cells appeared. The results of this study suggest that newly developed photoexcited TiO(2)/PEG have antitumoral activity. Photodynamic therapy utilizing this material can be a clue to a novel therapeutic strategy for glioma.