Patient 12, right sphenoid wing meningioma in a 79-year-old man. A, Before first surgery, contrast-enhanced axial T1 image shows an extra-axial enhancing mass lesion at the right sphenoid wing causing cavernous sinus obstruction. B, Corresponding DW MR image demonstrates the mass to be isointense. C, ADC map shows isointensity (absolute ADC = 0.90 × 10−3 mm2/s; NADC ratio = 1.23). Histologic examination showed benign meningothelial meningioma. D, Follow-up contrast-enhanced axial T1-weighted image before second resection shows the recurrent mass to be more extensive. E, Corresponding DW MR image of the tumor before second resection (arrow) is now hyperintense. F, ADC map shows hypointensity (absolute ADC has decreased to 0.60 × 10−3 mm2/s, and NADC ratio decreased to 0.77). Histologic examination revealed dedifferentiation to atypical meningioma.