<prompt> Answer this question truthfullyWhat role does MRI have in the diagnosis of Schwannoma?  <response>: <reason> Schwannomas have fairly predictable signal characteristics :T1: isointense or hypointense T1 C Gd: intense enhancement T2: heterogeneously hyperintense Antoni A: relatively low, Antoni B: high cystic degenerative areas may be present, especially in larger tumors T2: larger tumors often have areas of hemosiderinA number of signs can also be useful:split-fat sign: thin peripheral rim of fat best seen on planes along long axis of the lesion in non-fat-suppressed sequences target sign peripheral high T2 signal central low signal rarely seen intracranially 7 fascicular sign: multiple small ring-like structures 