Magnetic Resonance Spectroscopy (MRS) as a Predictor for the World Health Organization (WHO) Grading of Meningioma

Introduction: Meningiomas, the most common primary intracranial tumors, are typically benign. However, accurate preoperative grading is crucial for surgical planning and prognostication. MRS, a non-invasive technique, offers the potential to predict tumor grade.

Objective: To evaluate the efficacy of MRS in predicting the WHO grade of meningioma and its role in surgical planning.

Methods: A retrospective and prospective study was conducted on 62 patients with histopathologically confirmed meningiomas. MRS data was analyzed to determine the optimal cut-off values for metabolite ratios (Cho/Cr, Cho/Naa, Naa/Cr) to differentiate between WHO Grade 1 and 2 meningiomas.

Results: The study primarily included Grade 1 meningiomas (66.1%). While MRS showed potential in differentiating between grades, its accuracy was limited.
Metabolite ratios varied between grades. For Grade 1 meningiomas, mean Cho/Creat, Cho/NAA, and NAA/Creat ratios were 3.1 ± 2.3, 5.2 ± 4.5, and 1.15 ± 1.4, respectively. For Grade 2, these were 3.35 ± 5.01, 8.03 ± 11.7, and 1.97 ± 2.25. Despite differences, significant overlap hindered accurate differentiation. To assess predictive accuracy, sensitivity, specificity, and accuracy were calculated for optimal cut-off values. For Grade 1, Cho/Creat had 62.1% accuracy (65.9% sensitivity, 52.4% specificity), Cho/NAA had 49.1% (68.3%, 33.3%), and NAA/Creat had 38.0% (51.2%, 33.3%). For Grade 2, Cho/Creat had 37.9% (52.4%, 26.8%), Cho/NAA had 50.9% (61.9%, 39.0%), and NAA/Creat had 61.7% (66.7%, 58.5%).

Conclusion : While MRS offers valuable insights into tumor metabolism, its current role in preoperative grading of meningiomas is limited. Further research is needed to refine techniques, explore additional metabolites, and develop more robust predictive models.