The Role of Magnetic Resonance Spectroscopy in Grading Brain Glioma

Background: conventional magnetic resonance (MR) imaging are helpful in characterizing tumor aggressiveness, but grading using conventional MR imaging alone is often unreliable. Proton MR Spectroscopy (MRS) is a well-established technique for quantifying the brain regional biochemistry by providing valuable information on the metabolic composition within an area of tissue and comparing the relative concentration of these metabolites. The aim of this study is to evaluate the contribution of short and intermediate TE MRS in differentiation of high and low grade gliomas. Patients and Methods: a prospective cross sectional study conducted on selected patients with untreated gliomas whom were referred to the radiology department presenting with different neurological symptoms from April 2018 to February 2019. 1.5 Tesla MRI and MRS were performed before any interventional procedure. Histopathological diagnosis was obtained and all tumors enrolled were graded according to the current World Health Organization criteria. The main metabolites identified by MRS were N-acetyl-aspartate (NAA) at 2.02 ppm, creatine (Cr) at 3.0 ppm, choline containing compounds (Cho) at 3.2 ppm. The following metabolic ratios were calculated using standard commercial software: NAA/Cr, Cho/Cr, and Cho/NAA at both short and intermediate TE. Results: a total of 22 patients; (12 male and 8 females, age ranged 18–70 years). At intermediate TE, the difference between high and low grade tumors was statistically significant in Cho metabolite related ratios (Cho/NAA and Cho/Cr), p-value 0.001 and 0.003 respectively. At short TE, the difference between high and low grade tumors was statistically significant in Cho metabolite related ratios (Cho/NAA and Cho/Cr), P <0.001 and 0.01 respectively. On other hand, NAA/Cr ratio was statistically insignificant in differentiating low and high grade tumors. Conclusion: MRS is a non-invasive technique that provides an insight into the underlying biological structure of brain gliomas and in turn improves the diagnostic accuracy. Cho/Cr and Cho/NAA ratios were the most valuable indicators in assessing the tumor grade.