ORBITAL INVOLVEMENT BY WEGENERS GRANULOMATOSIS - IMAGING FINDINGS

OBJECTIVE. The purpose of this study was to define patterns of Wegener 's granulomatosis (WG) orbital disease involvement. SUBJECTS AND METHO DS. We evaluated the orbital examinations of 14 WG patients (CT for ni ne, MR imaging for three, and both CT and MR imaging for two) for the number of involved orbits, intraconal or extraconal location, involvem ent of the orbital apex, sinus involvement, bony erosion, and optic ne rve compression. MR images were analyzed for signal characteristics an d enhancement patterns. RESULTS. We found orbital disease to be unilat eral in 12 patients (86%) and bilateral in two patients (14%) (total o f 16 orbits). In 11 orbits (69%), coexistent orbital and sinus disease s with bony erosion were present. Orbital disease without sinus diseas e was seen in five orbits (31%). Intraorbital disease distribution was as follows: solely extraconal-seven orbits (44%) (four with involveme nt of muscle); intraconal with muscular involvement-one orbit (6%); co mbined intra- and extraconal-seven orbits (44%); and primarily orbital apex-one orbit (6%). Involvement of the apex was seen in six orbits. The WG mass was hypointense relative to orbital fat on three standard T2-weighted MR images. We saw homogeneous MR contrast enhancement in a ll four orbits studied on enhanced T1-weighted images. CONCLUSION. Int raorbital WG involvement is usually accompanied by paranasal sinus dis ease. A hypointense signal on T2-weighted MR images is helpful in sugg esting the diagnosis.