Somatostatin analogue scintigraphy in granulomatous diseases

Normal as well as activated lymphocytes and macrophages have previously been shown by radioreceptor analysis to express somatostatin receptors (SS-R). The somatostatin (SS) analogue [¹¹¹In-DTPA-d-Phe¹]octreotide (¹¹¹In-octreotide) is already used successfully in the visualization of a variety of neuro-endocrine tumours and malignant lymphomas. In the present study 20 consecutive patients were investigated, 12 with sarcoidosis, one with both sarcoidosis and aspergillosis, four with tuberculosis and three with Wegener's granulomatosis. For in vivo SS-R imaging, total-body scintigraphy was performed 24 and 48 h after the administration of ¹¹¹In-octreotide. Granuloma localizations could be visualized in all patients studied; additional sites were found in nine patients with sarcoidosis and in two patients with tuberculosis. In vitro autoradiography of fresh tissue biopsies, using the SS analogue [¹²⁵I-Tyr³]octreotide, showed binding at sites that were microscopically identified as granulomatous inflammation. These observations demonstrate the expression of SS-R by human granulomas. This scintigraphy procedure may contribute to a more precise staging and evaluation of granulomatous diseases, but more importantly it may be a sensitive indicator of the efficacy of glucocorticoid and/or immunosuppressive therapy.