Epidermoid cyst in a girl: Constructive interference in steady-state and diffusion-weighted imaging findings

Intracranial epidermoid cysts can closely mimic cerebrospinal fluid on magnetic resonance imaging and computed tomography. Epidermoid cysts are isointense to slightly hyperintense relative to cerebrospinal fluid on T1-, T2-, and proton density-weighted images. It is difficult to discern the exact extension of an epidermoid cyst with only T1-, T2-, or proton density-weighted imaging. In this exhibit, we present a case of intracranial epidermoid cyst, which closely mimicked an arachnoid cyst on routine magnetic resonance sequences. In the present case, we performed the constructive interference in steady-state (CISS) sequence and diffusion-weighted imaging. The CISS sequence depicted the epidermoid cyst as hypointense relative to cerebrospinal fluid and was considered to show the epidermoid cyst extension better than other routine sequences. The epidermoid cyst has typical high signal intensity on the diffusion-weighted images associated with low apparent diffusion coefficient values. © 2006 IOS Press. All rights reserved.