1-cholesterol granuloma..bright T1, T2, low DWI.no enhancement.(the bright T1 make it unique)
2-cholesteatoma..bright or dark T1, bright T2 and DWI.
3-cephalocele.as CSF, communicate with mackel's cave.
4-mucocele.bone expansion, dark T1, bright T2.
5-petrous spicitis.. petrous destruction, enhance.