Pituitary adenomas: The role of In-111-DTPA-octreotide SPET in the detection of minimal post-surgical residues

Scintigraphy with In-111-DTPA-octreotide (In-111-octreotide) enables the lo calization of tumours with somatostatin receptors on their cell membranes, of which pituitary adenomas are an example. Trans-sphenoidal excision of su ch tumours is sometimes incomplete and the detection of post-surgical resid ues is a difficult diagnostic task. In this study, we used In-111-octeotide SPET to visualize pituitary adenomas and their minimal residues. In positi ve cases, the indirect demonstration of the presence of somatostatin recept ors may be decisive for the planning of treatment. In-111-octreotide SPET w as able to visualize adenomas in 21 of 27 patients (77.7%) (10 GH-secreting , 10 PRL-secreting and 1 non-secreting). Repeat SPET after the recurrence o f clinical symptoms and hormone hypersecretion revealed intense In-111-octr eotide uptake by residues in 8 of 10 patients (4 GH-secreting and 6 PRL-sec reting). Magnetic resonance imaging was positive in only 3 of these 10 pati ents. Our results suggest that In-111-octreotide SPET, in combination with other imaging modalities, is useful in the diagnosis and follow-up of pitui tary adenomas. It ensures better selection of patients for treatment with s omatostatin analogues, both pre- and post-operatively, and assists in the d evelopment of personalized treatment plans. ((C) 1998 Lippincott Williams & Wilkins).