Context: Gliomas account for nearly 50 to 60% of primary brain tumors. Preoperative diagnosis and grading of cerebral gliomas aids in prognostication and forecasting treatment. MRI alone has been suboptimal for preoperative evaluation of gliomas and advance sequences like Proton Magnetic Resonance Spectroscopy (MRS) and Diffusion Weighted Imaging (DWI) have abetted to improve characterization of gliomas. Aim: To assess the efficacy of MRS and DWI in diagnosing cerebral gliomas. Material and Methods: A Diagnostic Efficacy study was carried out among 31 patients presenting with neurological symptoms and suspected to have gliomas through MRI. In addition, MRS and DWI were also performed along with histopathological grading among these patients. At MRS, nCho, Cho/Cr, Cho/NAA along with lipid and lactate peaks were assessed. In DWI, minimum apparent diffusion coefficient was calculated for the tumour (ADCT), peritumoural oedema (ADCP) as well a ratio of ADCT to the minimum ADC in the contralateral normal tissue (ADCN). Tumours were graded as high grade or low grade based on MRS and DWI findings. Results: Twenty nine out of the 31 patients (21 male and 10 female) in the age range of 8 to 71 years were confirmed to have glioma at histopathology. Of these, glioblastoma multiforme (GBM) were most common (n=13). At histology, 4 tumours were low grade (grade I:2, grade II:2); while 25 were high grade (grade III:12, grade IV:13). Conventional MRI showed a diagnostic accuracy of 80.60% in correctly classifying the various lesions and 82.76% for grading them. At MRS, there was a significant positive correlation of nCho (p=0.006) and Cho/Cr ratio (p=0.029) for grading of gliomas. Moreover there was a significant difference between these two parameters between high (I and II) and low grades (III and IV). Lipid and lactate peaks were also significantly associated with high grade gliomas (p value was 0.042 for lipids and 0.01 for lactate). On DWI, ADCT and ADC ratio had statistically significant negative correlation with increasing tumour grades (p value was 0.015 for ADCT and 0.006 for ADC ratio). These two parameters were significant in differentiating high grade from low grade gliomas (p<0.05). Combining the findings in MRS and DWI resulted in a sensitivity, specificity and accuracy of 100%, 50% and 93.10% respectively. Conclusion: MR Spectroscopy, using nCho and Cho/Cr and DWI using ADCT and ADC ratio were found to be useful in evaluating the grades of cerebral glioma. Conventional MRI, however, was indispensable because of its ability to characterize and classify gliomas into subtypes. Combination of conventional contrast enhanced MRI, MRS and DWI is most appropriate to evaluate gliomas preoperatively.

Keywords: Brain; Gliomas; Grading; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Diffusion Weighted Imaging; Apparent Diffusion Coefficient.