MRI OF LYMPHOMAS OF THE ORBITS AND THE PARANASAL SINUSES

Purpose: The purpose of this study was to point out MR characteristics of non-Hodgkin lymphomas of the orbits and the paranasal sinuses and the benefit of fat-suppressed contrast-enhanced sequences. Method: The MR images of 16 patients with lymphoma of the orbits and the paranasa l sinuses were retrospectively analyzed for signal intensity, contrast enhancement, bone destruction, and mass effect. The findings were con firmed by means of biopsy (Stage IE disease) or follow-up imaging afte r chemotherapy (Stage IV disease). Results: MRI clearly delineated the extension of the lymphomas. On the T1-weighted images, the signal int ensity of the lymphoma was hypointense compared with the gray matter o f the brain in 12 cases and intermediate in 4 cases. The T2-weighted f ast SE images showed a hyperintense signal in 12 cases, intermediate i n 3 cases, and even hypointensity in 1 case. All lesions enhanced afte r intravenous Gd-DTPA administration, reliably visible in the T1-weigh ted fat-suppressed sequences but not visible in three cases in the T1- weighted SE sequences. Bony wall destruction was evident in cases with paranasal but never in isolated orbital lymphoma. Conclusion: While e xtension of lymphoma can be accurately described by MRI, a specific di agnosis is not achievable on the basis of signal intensities and enhan cement patterns alone. Therefore, at least in cases of suspected Stage s IE and IIE, biopsy proof is needed. Fat-suppressed contrast-enhanced sequences possess the highest detection rate and should therefore alw ays be applied.