SUBARACHNOID SPACE DISEASE - DIAGNOSIS WITH FLUID-ATTENUATED INVERSION-RECOVERY MR-IMAGING AND COMPARISON WITH GADOLINIUM-ENHANCED SPIN-ECHO MR-IMAGING - BLINDED READER STUDY

`PURPOSE: To evaluate fluid-attenuated inversion-recovery (FLAIR) magn etic resonance (MR) imaging in a blinded reader study for the detectio n of proved subarachnoid space (SAS) disease. MATERIALS AND METHODS: F LAIR MR imaging was performed in 62 patients (21 with proved SAS or me ningeal disease) and 41 control patients. A subset of 24 patients (eig ht patients with proved SAS disease and 16 control patients) also unde rwent gadolinium-enhanced T1-weighted MR imaging. FLAIR images were in terpreted blindly and independently by two neuroradiologists. RESULTS: For SAS disease, the overall sensitivity, specificity, and accuracy o f FLAIR for both readers were 85%, 93%, and 90%. In the 15 patients wi th inflammatory or neoplastic meningitis only (six patients with acute subarachnoid hemorrhage [SAH] excluded), the sensitivity, specificity , and accuracy of FLAIR for both readers were 82%, 93%, and 90%. All s ix acute SAH cases were interpreted as abnormal on FLAIR images by bot h readers. In the 24 patients who underwent both FLAIR and gadolinium- enhanced T1-weighted MR imaging, the sensitivity, specificity, and acc uracy of FLAIR imaging were 86%, 91%, and 89%; the sensitivity, specif icity, and accuracy of gadolinium-enhanced T1-weighted imaging were 43 %, 88%, and 74%. CONCLUSION: FLAIR is highly sensitive and specific fo r the diagnosis of SAS disease. Unenhanced FLAIR is superior to gadoli nium-enhanced T1-weighted MR imaging for the diagnosis of SAS disease. These data have important implications, because FLAIR is performed wi thout the costs and inherent risks of intravenous contrast agents. FLA IR also appears to be highly sensitive but nonspecific for acute SAH.