MR OF EPIDERMOIDS WITH A VARIETY OF PULSE SEQUENCES

PURPOSE: To assess the usefulness of fluid-attenuated inversion recove ry (FLAIR) and constructive interference in steady state (CISS) sequen ces in depicting epidermoid tumors. METHODS: Six patients with surgica lly confirmed epidermoid tumors in the subarachnoid space were examine d with T1-weighted MR imaging with a spin-echo sequence, and with T2- and proton density-weighted imaging with a fast spin-echo sequence, a FLAIR sequence, and a CISS sequence. In the qualitative analysis, thre e observers compared the five sequences for visibility of tumors and p resence of artifacts. A quantitative analysis was also performed by me asuring the contrast-to-noise ratio. RESULTS: On visual assessment, th e FLAIR sequence depicted all tumors as hyperintense relative to cereb rospinal fluid. The CISS sequence depicted all tumors as hypointense r elative to cerebrospinal fluid and was considered to show tumor extens ion better than the FLAIR sequence. At quantitative analysis, the mean contrast-to-noise ratios of tumor to cerebrospinal fluid on T1-, T2-, and proton density-weighted images, and on FLAIR and CISS sequences w ere 2.85, 3.41, 4.42, 16.13, and 20.23, respectively. The contrast-to- noise ratios for the FLAIR and CISS sequences were significantly highe r than those for the T1-, T2-, and proton density-weighted sequences. The contrast-to-noise ratio was not significantly different between FL AIR and CISS sequences, although the CISS sequence was slightly superi or. CONCLUSION: CISS and FLAIR sequences depicted epidermoid tumors in the subarachnoid spaces better than conventional spin-echo images did . The CISS sequence produced a relatively constant contrast between th e tumors and less artifactual interference.