SOMATOSTATIN RECEPTORS IN THE ORBITS

In-111 pentetreotide has been recommended for the detection of somatostatin receptor (SSR) positive tumors. Sites with increased numbers of activated lymphocytes may also show In-111 pentetreotide with Graves' ophthalmopathy (GO) compared to various other orbital disorders. Five patients with GO, three patients with necrotizing scleritis, and two patients with orbital pseudotumor were imaged at 4 hours, 24 hours, and 48 hours after injection of In-111 penetreotide. Although planar images did not show considerable uptake, SPECT slices showed marked and persistent uptake in the orbits unilaterally in one patient, and bilaterally in three patients with GO. There was no significant correlation between the In-111 pentetreotide activity and the degree of opthalmopathy determined by Werner's classification. Pseudotumors also showed positive uptake. Early uptake was present in one patient with necrotizing scleritis because of Wegener's granulomatosis, and was completely diminished at 24 hours. Octreotide treatment in three patients with GO did not cause any clinical improvement. Although the presence of SSR, either on the infiltrated lymphocytes or on fibroblasts, implies that octreotide treatment for GO can be considered, the results are not encouraging. Nonspecific binding might be present when uptake patterns of orbits and persistence of activity during octreotide treatment are considered.