[Aspects of FLAIR sequences, 3D-CISS and diffusion-weight MR imaging of intracranial epidermoid cysts].

We propose to assess the usefulness of diffusion-weighted MR Imaging (DWI), fluid-attenuated inversion recovery (FLAIR) and constructive interference in steady state (CISS) sequences in depicting epidermoid cysts (EC). FLAIR, CISS and DWI were obtained in 7 patients among 22. All patients were studied with T1 and T2 sequences. On Spin Echo images, EC demonstrate signal similar to LCS, which may lead to difficult differentiation between EC and arachnoid cyst (AC), specially for inexperienced radiologists. EC appear with a heterogeneous signal on T1 images (32%), irregular limits (91%) and with extension through foramen of Pacchioni in 18% of cases. On FLAIR sequence, the tumors were heterogeneous, different from void signal of CSF in 86% of cases. On CISS sequence, the tumors appear heterogeneous, hyperintense but less than LCS and with irregular limits in all cases. Some more, CISS images allowed to appreciate exact tumor extension and their relations with nerves and vessels. On DWI images, signal is hyperintense in all cases. Our study exhibited the great usefulness of DWI, CISS and FLAIR sequences in diagnosis of EC and in differentiating EC from AC.