Evaluate the effectiveness of using diffusion-based magnetic resonance imaging to estimate histological grade of the meningiomas and to explore the relation of apparent diffusion coefficient (ADC) value and tumor grade

AIM: Meningiomas are the most common intracranial tumors of the central nervous system. Besides being the most common extraaxial tumor of the intracranium, they comprise about 13-26% of all intracranial tumors. These tumors are classified as grade 1, grade 2 and grade 3 by World Health Organisation. Most of the meningiomas are grade 1 (90%) and the rest are grade 2 (4.7-7%) and grade 3 (1- 2.8%) tumors. The treatment, recurrence and long-term prognosis of grade 2 and 3 tumors show a significant difference from grade 1 tumors. Therefore, determining the histologic grade of the tumor and some pathologic features preoperatively are very important to decide treatment modality, predict the recurrence rates and longterm prognosis. There is numerous research about the use of different techniques in evaluating tumor grade and some pathological features. The aim of this study is to evaluate the effectiveness of using Diffusion-Based Magnetic Resonance Imaging to estimate histological grade of the meningiomas and to explore the relation of Apparent Diffusion Coefficient (ADC) value and tumor grade. Materials and methods: 86 patients with histopathologically-diagnosed meningioma who pre-operatively scanned with conventional Magnetic Resonance Imaging and Diffusion-Based Magnetic Resonance Imaging and went into surgery between 2010- 2018 in Dicle University Neurosurgery Department have been evaluated in retrospective approach. ROI has placed in the largest diameter of the tumor to encompass tumor that axial section and ADC value has measured. Results: Mean ADC values for the low-grade tumors calculated as 883,8±146,78mm2/s and for high-grade tumors calculated as 820,62±126,32 mm2/s. There weren't a statisticaly difference between the ADC values of patients with grade 1 tumor and grade 2 and 3 tumors. Conclusion: We haven't detected a significant difference in the ADC values between low and high-grade meningiomas. We didn't find DAG and ADC measurements reliable for detecting the grade in meningiomas. These techniques shouldn't be used to determine surgery and treatment strategies.