Combined fat- and water-suppressed MR imaging of orbital tumors

BACKGROUND AND PURPOSE: The use of a high-resolution T2-weighted MR sequenc e, which suppresses signal from both fat and mater, has been shown to be hi ghly effective for depicting areas of inflammatory damage within the optic nerve. The ability of this sequence to show neoplastic and inflammatory orb ital lesions, which may mimic neuritis, is unknown. This study was designed to examine the characteristics of such a sequence for the investigation of orbital mass lesions. METHODS: Twenty-eight patients with known or suspected mass lesions of the orbit and six healthy volunteers were recruited for study. Imaging was perf ormed with a 1.5-T MR unit. Participants were examined by selective partial inversion recovery (SPIR) sequences with T2-weighted fast spin-echo acquis ition, selective partial inversion recovery/flnid attenuated inversion reco very (SPIR/FLAIR) sequences with fast spin-echo acquisition, short tau inve rsion recovery (STIR) sequences with fast spin-echo acquisition, and SPIR s equences with contrast-enhanced T1-weighted fast spin-echo acquisition. Two neuroradiologists, using a randomised, blinded method, scored images for l esion presence and extent. Lesion extent was defined as the number of image s with visible abnormality, and was compared with the standard of reference established at a later date by consensus review of all imaging sequences. The ability of the sequences to show the presence and extent of pathologic lesions was compared. RESULTS: The SPIR/FLAIR sequence showed both the presence and extent of orb ital masses significantly better than did either STIR or T2-weighted SPIR s equences (P<.01 and P<.001, respectively). Contrast-enhanced T1-weighted SP IR images ranked better than SPIR/FLAIR images, although the difference fai led to reach statistical significance. In the orbital apex, the SPIR/FLAIR technique was superior to all other techniques used. This reflected its abi lity to distinguish enhancing, pathologic lesions from enhancing, normal an atomy. CONCLUSION: SPIR/FLAIR is an appropriate screening technique for orbital ma sses and offers significant advantages over currently used fat-suppressed s equences for the investigation of orbital disease.