THE ROLE OF RADIOLABELED SOMATOSTATIN ANALOGS IN ADRENAL IMAGING

We investigated the role of radiolabeled somatostatin analogs (SAs) in adrenal imaging. We evaluated 15 patients (6 men and 9 women, mean ag e 47 +/- 17 years) with imaging-detected adrenal tumors. Patient popul ation was divided into two groups on the basis of the nature of adrena l lesions. Group 1 consisted of patients with benign adrenal lesions ( n = 10). Group 2 consisted of patients with malignant adrenal lesions (n = 5). Pathology examinations were obtained in 13 cases: 7 pheochrom ocytomas, 2 adenomas, 2 cysts, 1 carcinoma, and 1 fibro-histiocytoma. One patient had a proven diagnosis of non-small-cell lung cancer assoc iated with the presence of a right adrenal mass. The last patient had a clinical diagnosis of Werner syndrome associated with the presence o f a large left adrenal mass. All patients underwent scintigraphic stud ies using radiolabeled SAs, of which indium-111 (In-111) pentetreotide was used in 11 cases and technetium-99m (Tc-99m)-labeled peptides (P- 587 or P-829) were used in the remaining four cases. No significant la beled SAs uptake was observed in the majority (8 of 10, 80%) of the be nign adrenal lesions (Group 1); however, increased uptake was found in two benign pheochromocytomas. Conversely, significant labeled SAs upt ake was observed in the majority (4 of 5, 80%) of the malignant adrena l lesions (Group 2); however, the last lesion (carcinoma) did not show abnormal uptake. Results of this study show that the majority of beni gn adrenal tumors do not concentrate radiolabeled SAs; conversely, the majority of malignant adrenal lesions show significant SAs uptake, su ggesting the presence of somatostatin receptors. This finding may allo w the use of somatostatin as a treatment agent in malignant adrenal tu mors. Thus, the main role of labeled SAs in adrenal imaging consists o f lesion characterization rather than tumor detection and localization .