Investigation of the relationship between MRI features of meningiomas and histopathological grade

Meningiomas are tumors that arise from the arachnoid cap cells that form the arachnoid membrane and are usually benign in nature, but can rarely exhibit atypical or malignant behavior. Histopathologic evaluation is critical to confirm the diagnosis of meningioma, classify its subtype, and determine its grade. The World Health Organization has divided meningiomas into 3 histopathologic groups. Grade I tumors rarely recur after total excision, while grade II meningiomas recur eight times more often than grade I tumors despite total excision. Grade III tumors are much more aggressive with a median survival of two years or less. Due to the locally invasive nature of grade II-III meningiomas, adjuvant radiotherapy is recommended to treat these tumors. The aim of this study is to determine the correlation between histopathological grading and preoperative MRI results in meningioma patients in order to guide treatment planning. To evaluate the features such as nADC (normalized ADC) and ADC values, T2A signal value of the lesion, maximum diameter and whether the lesion is accompanied by edema and to determine the success of the results in distinguishing histopathological grades. The scope of the study consists of a total of 59 patients, 14 male and 45 female, over the age of 18, who were pathologically diagnosed with meningioma in our center between 01.04.2014 and 01.04.2024 and who had preoperative cranial MRI examination. The study was initiated with the ethical approval dated 31.01.2025 and numbered E.938816 from the Ethics Committee of Suleyman Demirel University Faculty of Medicine for Non-Drug and Medical Device Research. The compilation of all clinical and imaging information was carried out in accordance with the Declaration of Helsinki. Patients were included in two study groups as Typical (grade I meningioma) and Atypical (grade II meningioma). Patients belonging to the typical meningioma group constituted the majority with 74.6% (n=44) data, while the remaining patients were patients with atypical meningioma. nADC values showed a significant difference between the two groups (p=0.011). While the nADC mean was 1.10±0.19 in the typical patient group, it was measured significantly lower in the atypical meningioma patient group and was 0.96±0.16. T2A measurement values were observed significantly lower in the typical patient group (p=0.004). Tumor sizes were found to be significantly lower in the typical patient group (p<0.001). According to the established logistic regression model, nADC value, T2A signal value and tumor size were determined as significant diagnostic factors on histopathological grading (p<0.05). According to the ROC analysis models, nADC, ADC, T2A and tumor size measurements were found to be successful diagnostic markers in distinguishing typical and atypical meningiomas. In conclusion, there are significant relationships between preoperative MR imaging findings and histopathological grading results in meningioma patients. When meningioma is diagnosed, conventional and diffusion MRI findings, especially nADC value, appear to be good markers in guiding surgery or predicting whether the tumor grade increases in follow-up patients with typical meningioma.