Apparent Diffusion Coefficient in Predicting the Preoperative Grade of Meningiomas.

Objective To investigate the relationship between the apparent diffusion coefficients (ADC) value obtained from magnetic resonance imaging (MRI) and histopathologic grade of meningiomas. Study design Observational study. Place and duration of study Department of Radiology, Istanbul Medeniyet University, School of Medicine, Istanbul, Turkey between January 2015 and June 2019. Methodology Data of 45 patients with meningiomas, who underwent surgery at the University Hospital, were retrospectively reviewed; 28 patients were enrolled in the study. The pathology preparations of the patients were re-evaluated according to the World Health Organisation (WHO) 2016 classification updated by a neuropathologist. ADC values were measured in a standard region of interest range from the three consecutive sections where the mass had the largest width and from the opposite white matter. Results Fourteen patients (50%) were diagnosed with WHO grade I tumor, 11 with grade II (39.3%), and three with grade III (10.7%). The ADCmin value was found statistically significant for the differentiation of tumor grades (p = 0.018). The cut-off point of the ADCmin value was 0.634x10-3mm2s for the differential diagnosis of grade I and grade II/III meningiomas. The sensitivity of the cut-off value was found as 86% and its specificity as 57%. The patients with increased cellularity and Ki67 proliferation index had statistically significantly lower ADCmin values (p = 0.025). Conclusion The data of this study show a significant difference in the ADCmin values on MRI between low- and high-grade meningiomas. A negative correlation was found between histopathologic grade and ADCmin. Key Words: Meningioma, Apparent diffusion coefficient, Magnetic resonance imaging, Histopathological grade, Quantitative.