The aim of this study was to investigate the predictive role of the orbital
somatostatin receptor scintigraphy with (99m)Tc-
EDDA/HYNIC-TOC ((99m)Tc-TOC) to detect clinical stage of
Graves' ophthalmopathy and the response to
corticosteroid therapy. The subjects of the experiment were 46 patients with
Graves' ophthalmopathy (GO) and four volunteers without
eye disease or GO as the normal group (NG). Single photon emission computed tomography (SPECT), computed tomography (CT) and the left and right lateral position planar imaging of the heads of the all subjects were obtained 4 h after the
intravenous injection of 555 MBq of (99m)Tc-TOC. The (99m)Tc-TOC SPECT/CT was repeated 3 months later. 35 (35/46) patients were received
corticosteroid therapy (
prednisolone, 10 mg po tid ) for 3 months, however, the other 11 patients as control groups did not receive any treatment. The treatment effect was evaluated both by the orbital (99m)Tc-TOC uptake and NOSPECS. A significant decrease in the O/OC ratio was observed in 22 GO patients between pre- and post-treatment (1.64 ± 0.13 vs. 1.21 ± 0.09, P < 0.05). There were neither significant difference of the O/OC ratio in 13 GO patients between pre- and post-treatment periods, nor significant difference in the 9 (9/11) patients before and after three months. Orbital (99m)Tc-TOC scintigraphy is a feasible technique to estimate the
Graves' ophthalmopathy activity and predict the response to subsequent
corticosteroid therapy in GO patients. The technique could be a useful tool for physicians not familiar with CAS determination.