This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Epidermoids can be differentiated from arachnoid cyst on MRI by: 
Select and explain. 
A. Contrast enhancement, B. Smooth margins, C. Restricted diffusion, D. CSF signal on FLAIR
C: Restricted diffusion
Answer: C: Restricted diffusion 
Explanation: C i.e. Restricted diffusion Epidermoids can be differentiated from arachnoid cyst characteristically by hyper-intense diffusion weighted images because of restricted diffusion of epidermoid cystQ. FLAIR and proton images are less specific than DWI.