Objective: The aim of this study was to clarify whether Tc-99m HIG (Polyclonal Human Immunoglobulin G) can image and determine the severity of orbital involvement in patients with Graves' ophthalmopathy.
Materials and methods: Twenty-six patients between 19 and 56 years old with Graves' ophthalmopathy were examined. All patients received approximately 370 MBq Tc-99m HIG by i.v. injection. Planar and SPECT examination were performed 4 hours after the injection. Visual and semiquantitative evaluations were performed for both orbits by two independent observers,
Results: Clinically active ophthalmopathy patients had noticeably increased orbital accumulation of Tc-99m HIG. In patients with inactive disease, and 14 of 19 had no uptake, whereas 5 patients had orbital radioactivity accumulation. The duration of Graves' ophthalmopathy did not correlate with the presence of active ophthalmopathy and Tc-99m HIG grade. There was no correlation between clinical classification and clinical activity (r = 278). There was a good correlation between clinical activity and the radioactivity grade with r = 0.666 (p = 0.01). The clinical classification closely correlated with Tc-99m HIG grade (r = 0.423, p = 0.05).
Conclusion: Tc-99m HIG scan can clearly identified clinically active patients, and subclinicial inflammation can be shown by this scintigraphic evaluation. The current preliminary results suggested that Tc-99m HIG SPECT might be useful for the assessment of disease activity in Graves' ophthalmopathy.