Background: The present study is aimed to assess the contribution of MR spectroscopy in correlation with other MRI sequences towards the evaluation of brain tumors and to diagnosing and grading the brain tumors with histopathological correlation.

Methodology: Analysis of spectra of 30 patients with brain tumors (27 intra axial and 3 extra axial) was done.

Results: 6 with GBM, 4 with anaplastic astrocytoma, 6 with diffuse infiltrative astrocytoma, 1 with oligodendroglioma, 1 with gliomatosis cerebri, 1 with ependymoma, 5 with metastasis, 1 with choroid plexus papilloma, 1 with medulloblastoma,1 with lymphoma, 2 with vestibular schwannomas and 1 with meningioma. Histopathology was not done in five cases. Five tumors didn’t correlate histopathologically. MRS of tumors shows decreased NAA levels since neurons are superseded by the neoplasm cells. Furthermore, increase in choline levels are seen. Some tumors show Lac and Lip signals, which are markers of anaerobic metabolism and necrosis. High Lac-Lip concentration helps to distinguish high and low grade gliomas. Glioblastomas have a higher Lac-Lip concentration than anaplastic astrocytomas. Absence of the Lac-Lip signal does not exclude the diagnosis of high grade glioma. In our study peak Lac-Lip was present in all the cases of glioblastoma in the necrotic component of the tumor. Cho contents measured with the Cho/Cr ratio increase with the grade of astrocytoma. The decrease of Cho/Cr ratio in some glioblastoma is explained by the presence of necrosis in these tumours. No significant difference in NAA/ Cr ratio was observed in different types of gliomas. Other intraaxial brain tumors namely Gliomatosis cerebri, medulloblastoma, ependymoma and choroid plexus papilloma showed elevated Cho/Cr and Cho/NAA ratios as well as decreased NAA/Cr ratios of varying degrees within the areas of hyperintensity on T2-weighted images and in enhancing part of the tumor. In lymphoma, similar findings are found except for increased lipid-lactate peak. Extra-axial tumors namely schwannoma and meningioma showed elevated Cho/Cr and Cho/NAA ratios as well as decreased NAA/Cr ratios of varying degrees and there was an alanine peak detected in meningioma.

Conclusion: The study conclude that in vivo MR spectroscopy can be used as a reliable method for distinguishing neoplastic from non-neoplastic lesions and also helpful in glioma grading. Some features of tumors on conventional MRI (e.g. contrast enhancement, surrounding edema, signal heterogeneity, necrosis, haemorrhage and midline crossing) suggest a high grade. Accurate grading of gliomas on the basis of MRS alone may be difficult. Combining MRS with conventional and other advanced MR imaging techniques, grading becomes more precise.