The Role of Magnetic Resonance Spectroscopy, Magnetic Resonance Perfusion and Positron Emission Tomography-Computed Tomography in Post-Radiotherapy Evaluation of Gliomas to Detect Recurrence

Abstract

Abstract Background and Aim: In this article, the findings of magnetic resonance spectroscopy (MRS), magnetic resonance (MR) perfusion, and positron emission tomography (PET) will be compared and finally correlated with the histopathological examination in all patients having positive imaging findings. The sensitivity and specificity of MRS, MR perfusion, and PET in diagnosing residual/recurrent glioma would be estimated using the histopathological diagnosis as a gold standard. Materials and Methods: Twenty-nine cases of intracranial glioma that had undergone surgery, followed by adjuvant radiotherapy were enrolled in the study. All 29 patients underwent MRS, MR perfusion, and fluorodeoxyglucose (FDG) PET. Results: The sensitivity of MRS to detect recurrence was found to be 83.3% and specificity was 100%. The positive predictive value (PPV) and negative predictive value (NPV) were 100% and 33.3%, respectively. The diagnostic accuracy of MRS was found to be 84.6%. The sensitivity and specificity of MR perfusion to detect recurrence were 91.7% and 100%, respectively. The diagnostic accuracy of MR perfusion is 92.3%. The NPV of MR perfusion was found to be 50%. The sensitivity of PET scans to detect recurrence was 83.3% and specificity was 100%. The PPV of PET was 100% and the NPV was 33.3%. The diagnostic accuracy of the PET scan was found to be 84.6%. Conclusions: Our study shows that all three modalities are useful, however, MR perfusion study is better than MRS and FDG PET in detecting recurrence. MR contrast with perfusion and spectroscopy and FDG PET scan should be included in the protocol for radiotherapy-treated gliomas to differentiate between radiation necrosis, postradiotherapy gliosis, and recurrent/residual tumor.