Comparative Analysis of Magnetic Resonance Spectroscopy and Post-contrast Magnetic Resonance Imaging in the Evaluation of Intracranial Ring-Enhancing Lesions.

Background Intracranial ring-enhancing lesions are diagnostically heterogeneous because infective, neoplastic, demyelinating, and vascular etiologies may show overlapping conventional magnetic resonance imaging (MRI) appearances. This study evaluated and compared the diagnostic performance of post-contrast MRI and magnetic resonance spectroscopy (MRS) in the etiological characterization of intracranial ring-enhancing lesions. Materials and methods This hospital-based prospective observational, non-interventional study included 45 patients with intracranial ring-enhancing lesions. All patients underwent conventional MRI, diffusion-weighted imaging, apparent diffusion coefficient (ADC) assessment, post-contrast imaging, and MRS. Lesion morphology, enhancement pattern, diffusion characteristics, ADC findings, and spectroscopic metabolite patterns were recorded. Final etiological diagnosis was established using a composite reference standard based on histopathology, microbiology, therapeutic response, and clinicoradiological follow-up, wherever available. Categorical variables were summarized as frequencies and percentages. Associations between imaging findings and final diagnosis were assessed statistically, and diagnostic performance was calculated using sensitivity, specificity, positive predictive value, and negative predictive value. Results Infective lesions were the most common etiology, accounting for 62.2% of cases, followed by neoplastic lesions in 17.8%, demyelinating lesions in 11.1%, and vascular lesions in 8.9%. Perilesional edema was present in all cases, while mass effect showed a statistically significant association with lesion etiology. Central necrosis and qualitative diffusion restriction were not significantly associated with final diagnosis. ADC assessment showed better diagnostic correlation with lesion etiology. MRS demonstrated stronger diagnostic separation than post-contrast imaging, particularly through elevated choline-based ratios in neoplastic lesions and lipid-lactate patterns in infective lesions. Post-contrast MRI showed sensitivity, specificity, positive predictive value, and negative predictive value of 86.7%, 75.0%, 81.2%, and 80.0%, respectively. MRS showed higher corresponding values of 93.3%, 85.0%, 87.5%, and 91.0%, respectively. Conclusions Post-contrast MRI remains essential for anatomical localization and morphological assessment of intracranial ring-enhancing lesions, but its independent diagnostic specificity is limited by overlapping enhancement patterns. MRS provides additional metabolic information and demonstrated superior diagnostic performance in this study. A multiparametric MRI approach combining morphology, diffusion assessment, ADC evaluation, post-contrast imaging, and spectroscopy improves non-invasive etiological characterization and may support more confident clinical decision-making.