Background: The primary aim of this study was to evaluate the individual and combined efficacy of magnetic resonance imaging (MRI) parameters, which include MRI perfusion, MRI diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) in the grading of gliomas as low grade versus high grade. The pre-operative imaging-based grading of gliomas by multiparametric MRI was compared with the gold standard histopathological studies. Methods: A total of 22 patients referred to the radiology department for multiparametric MRI of the brain with presumptive diagnosis of glioma on computed tomography/MRI were included in the study. Conventional T1, T2 and fluid-attenuated inversion recovery images were obtained followed by perfusion MRI using gadopentetate dimeglumine (Magnevist) administration. This was followed by DWI and MRS. Results: Our statistical analysis demonstrated that a cut-off of apparent diffusion coefficient value of 954.085 (10–6 mm2/Sec) provides a sensitivity and specificity of 87.5% and 85.7%, respectively, in differentiating low-grade gliomas (LGGs) from high-grade gliomas (HGGs). A choline/creatine ratio cut-off value of 2 provides sensitivity and specificity of 100% and 92.9%, respectively, while a cut-off value of 1.45 of choline/N-acetylaspartate ratio provides both sensitivity and specificity of 100% in differentiating LGG from HGG. A cut-off of 1.9 for maximum relative cerebral blood volume (rCBV) value provides both sensitivity and specificity of 100% in differentiating LGGs from HGGs. Conclusions: We concluded that perfusion MRI (rCBV) was the best parameter among perfusion MRI, DWI and MRI spectroscopy in differentiating HGGs from LGGs. Combined multiparametric results showed a diagnostic accuracy, sensitivity, specificity, positive predictive value and negative predictive value of 86.4%, 82.4%, 100%, 100% and 62.5%, respectively, on comparison with gold standard histopathological grading.

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Background: Viral encephalitis and glioblastomas can have a very variable clinical and radiological presentation. Although they are both relatively rare, they are known to mimic each other. Methods: In this study, we retrospectively analysed the radiology databank from 2010 to 2020 to find cases which were initially suspected to be viral encephalitis based on their imaging and clinical parameters but were later diagnosed with glioblastomas on final histopathology. The initial imaging at the time of presentation was reviewed by three radiologists having experience of 18, 15 and 6 years in neuroimaging, and the follow-up imaging data were also reviewed by the same set of radiologists, and the results were recorded. Age- and sex-matched controls of confirmed viral encephalitis were also extracted from the same database. Results: We found three such cases which were initially diagnosed with viral encephalitis but rapidly progressed to glioblastoma in the region of suspected encephalitis. The average age of these patients was 60 years and all of them were males. All these cases had a very short history and the cerebrospinal fluid examination of all of these patients had tested negative for herpes simplex virus at the time of initial presentation. Conclusions: The development of glioma exactly at the site of initial encephalitic abnormality suggests an association between these two entities, which needs further prospective studies for validation and correlation with post-mortem histopathology. Furthermore, the fact that these glioma patients showed initial clinical improvement with antiviral drugs suggests a strong point towards such an association.