Differentiating Intracranial Cysts

Common cystic brain lesions can be differentiated by evaluating the MRI sequences.

• Arachnoid cysts strictly follow cerebrospinal fluid (CSF) on all sequences and suppress completely on FLAIR.

• Epidermoid cysts mimic CSF on T1 and T2 but critically do not suppress completely on FLAIR and exhibit marked restricted diffusion on DWI.

• Dermoid cysts contain macroscopic fat, appearing hyperintense on T1-weighted images with signal loss on fat-saturated sequences