111In-octreotide in the evaluation of autoimmune thyroid diseases

Aim of our study was to evaluate the uptake of Indium-111 Octreotide (OCT) at the level of thyroid and orbits in autoimmune thyroid diseases. Nine patients with Graves' disease (GD) who were also affected with thyroid associated ophthalmopathy (TAO) and four patients with Hashimoto's thyroiditis (HT) were evaluated. A patient with lung cancer, presenting ophthalmopathy did not related to autoimmune dysthyroidism, was also studied. All patients with ophthalmopathy were evaluated by a Clinical Activity Score and an A-scan standardized echography. Multiple planar images were acquired over a 24-hour period after i.v. injection of 111 MBq of 111In-OCT. A SPECT study was also obtained in 7 patients five hours after the injection. A qualitative analysis was performed. Semiquantitative ratios comparing the counts on the thyroid with respect to background (T/BK) and on the orbits and brain with respect to the blood-pool were also obtained. Thyroid uptake of OCT was higher in GD with respect to HT, and was not related to the functional state of the gland. The highest T/BK ratio was observed at the 24 hour control. Intense orbital uptake was observed only in case where a clinically active ophthalmopathy was present.