Indium-111 octreotide in Graves' disease and in the evaluation of active exophthalmos

Thyroid Associated Ophthalmopathy (TAO) is an autoimmune disorder generally associated with Graves' disease (GD). The aim of our study was to evaluate the uptake of indium-111 Octreotide (111In-OCT), a somatostatin (SS) analogue able to bind specific SS receptors, at the level of the thyroid and orbits in patients with TAO. Seven patients with exophthalmos were investigated: six had GD while one was affected with a non small cell lung cancer (NSCLC). One patient with GD had undergone total thyroidectomy (TT) for a thyroid cancer. At the time of the study two patients were hyperthyroid, four were euthyroid and one was hypothyroid. 111 MBq of 111In-OCT were i.v. injected and two 30-minute scans were performed at 4 and 24 hours; 5 minute planar images were also obtained at 25, 60 and 120 minutes. A 180 degrees SPECT was carried out 5 hours after the injection in one patient. A qualitative analysis was performed, comparing these images with those obtained in 7 control patients without thyroid illness or exophthalmos. Moreover, in the TAO patients thyroid, orbit and brain counts were evaluated in comparison with background (BK) and blood activity (BA), measured at the level of the venous longitudinal sinus. In GD intense thyroid uptake was demonstrated independently of the functional state, with highest ratio compared to BK seen at 24 hours. Low uptake in the patient with NSCLC, no activity in the patient with GD that underwent TT, and slight or absent thyroid uptake in the controls were observed. Intense uptake was seen in the orbits of the patient who clinically had the most severe ophthalmopathy.(ABSTRACT TRUNCATED AT 250 WORDS)