Grading meningiomas using mono-exponential, bi-exponential and stretched exponential model-based diffusion-weighted MR imaging

AIM To prospectively evaluate and compare the potential of various diffusion metrics obtained from mono-exponential model (MEM), bi-exponential model (BEM), and stretched exponential model (SEM)-based diffusion-weighted imaging (DWI) in the grading of meningiomas. MATERIAL AND METHODS Consecutive 93 patients with histopathologically confirmed meningiomas received DWI of multiple b-values. Apparent diffusion coefficient (ADC), pure molecular diffusion (D), pseudo-diffusion coefficient (D*), perfusion fraction ( f ), water molecular diffusion heterogeneity index (alpha), and distributed diffusion coefficient (DDC) were calculated and compared between low-grade and high-grade meningiomas. Receiver operating characteristic and multivariable stepwise logistic regression analyses were performed to evaluate the diagnostic performance of different parameters. RESULTS The mean and normalised ADC, D, f , and DDC values were significantly lower in high-grade meningiomas than those in low-grade meningiomas (all p 0.05). The AUCs of D and DDC were significantly higher than that of f in the differentiation (all p 0.05). D was the only variable that could be used to independently differentiate high-grade and low-grade meningiomas ( p 0.001). CONCLUSION Different models of DWI, including MEM, BEM, and SEM, are useful in the differentiating high-grade and low-grade meningiomas; however, D obtained from BEM is the most promising diffusion parameter for predicting the grade of meningiomas.