Benign Versus Atypical/Malignant Meningiomas on DWI

Benign meningiomas have a variable appearance on diffusion-weighted images, they tend to have higher Dav values compared with normal brain, with the exception of densely calcified or psammomatous meningiomas, which may have a low Dav.  Furthermore, the average Dav values of malignant and atypical meningiomas are significantly lower compared with benign meningiomas.  It seems that the quantification of the diffusion constant may reliably predict the histopathologic features of meningiomas before resection, useful because atypical and malignant meningiomas are more prone to recurrence and aggressive growth. 

Learning Point:  Malignant meningiomas will be  hyperintense (‘‘lightbulbs’’) on the diffusion- weighted images and hypointense on the corresponding ADC maps.