Value of Magnetic Resonance Spectroscopy in Differentiation between Residual/Recurrent Primary Brain Tumors and Radiation Necrosis

Background: Residual/recurrent tumors are the primary clinical challenge encountered during the diagnostic workup of cases who have received prior treatment for brain tumors. Magnetic resonance spectroscopy was employed to assess the efficacy of this examination in recognizing radiation necrosis (RN) from residual/recurrent primary brain lesions. Methods: This prospective study involved 30 cases with primary brain tumors receiving radiotherapy and on follow-up in Radiology Department of Benha University hospitals. All cases were divided into 2 groups according to MRS diagnosis: Group I (n=7): cases with RN and group II (n=23): cases with recurrent tumors. Results: MRS diagnosis using Choline (Cho) / N-acetyl aspartate (NAA) had 72% sensitivity, 60% specificity, 90% Positive (PPV) and 30% Negative (NPV) predictive values and 70% diagnostic accuracy. MRS diagnosis using Cho/Creatine (Cr) had 85.71% sensitivity, 55.56% specificity, 81.82% PPV, 62.50% NPV and 76.67% diagnostic accuracy. The proposed final diagnosis had 84.21% sensitivity, 75.00% specificity, 84.21% PPV, 75.00% NPV and 83.33% diagnostic accuracy.Conclusions: The differentiation between tumor recurrence and RN is facilitated by MRS, which is both safe and informative. Examination of numerous regions of the high-volume lesions is necessary. Recurrent malignancies were significantly more accurately predicted by the Cho/NAA and Cho/Cr ratios, as indicated by the meta-analysis. In this regard, MRS imaging functions as an informative instrument for the differentiation of necrosis and tumor recurrence.