Magnetic Resonance Spectroscopy in Evaluation of Focal Brain Lesions- A Cross-sectional Prospective Study

Abstract

Introduction: The characterisation of intracranial mass lesions only with the help of conventional magnetic resonance imaging alone may be inconclusive. Magnetic Resonance Spectroscopy (MRS) is a non invasive technique which is superior to Magnetic Resonance Imaging (MRI) in the characterisation of brain lesions. Magnetic resonance spectroscopy is comparatively fast, non-invasive method that gives biochemical analysis of the normal brain parenchyma and of the pathological processes. Magnetic resonance spectroscopy has the advantage of providing characterisation of tissues based on their molecular composition. It gives information about neuronal vitality, cell proliferation, degradation and energy metabolism. Aim: To describe the spectrum of magnetic resonance spectroscopy in focal brain lesions and to detect the metabolic and biochemical changes in various focal brain lesions. Also, to distinguish neoplastic from non-neoplastic lesions. Materials and Methods: This prospective study was carried out at Department of Radiodiagnosis, Sri Manakula Vinaynagar Medical College and Hospital, Puducherry, India for a period of 18 months from November 2017 to April 2019. A total of 40 MRI brain with clinically suspected brain lesions were included in the study. Magnetic resonance spectroscopy studies were performed in all patients with focal brain lesions. On the basis of spectral and distribution patterns of the pathologic spectra seen in MR spectroscopy, a qualitative analysis was done. The metabolic area ratios Choline/Creatinine (Cho/Cr)/Cr, NAA/Cho and NAA/Cr were evaluated (NAA- N-acetyl, Cho- choline, Cr- creatine). Data was collected using prescribed proforma and analysed using Statistical Package for the Social Sciences (SPSS) 22 version software. Results: Out of the 40 patients evaluated 11 cases were high grade gliomas, seven cases were Neurocysticercosis, five low grade glioma, five meningioma, four metastasis, four tubercular abscesses, two tuberculoma and two lymphoma. Increased Cho/ Cr ratio was noted in neoplastic lesions when compared to non neoplastic lesions. Conclusion: The MRS in addition to appropriate conventional MRI sequences provides useful supplementary information and has a potential to validate treatment strategies. Neoplastic lesions show elevated choline and Cho Cr ratio with reduction in N-acetyl aspartate (NAA), whereas non neoplastic lesions show decreased Cho/Cr ratio. Hence, MRS could be a problem solving tool in differentiating neoplastic from non neoplastic lesions.