Somatostatin receptor imaging: a preliminary experience in forty-nine patients

We report our experience with the 111In-pentetreotide scanning of 47 adult patients presenting with neuroendocrine tumors (n = 38) or malignant pheochromocytomas or related tumors (n = 9), and 2 children with metastatic neuroblastomas. A dynamic study was performed after i.v. administration of 50-190 MBq of 111In-pentetreotide followed by a whole body scan at 1.5-4 hours and at 24 hours. Where indicated, tomoscintigraphy or a dual isotope bone, liver or kidney scan was performed in order to improve the anatomical definition. Lesions were visualized in the earliest phases of the examination but contrast was enhanced on delayed images due to an improved signal to background ratio. In 9/49 patients, octreotide scan (OS) detected unknown tumors sites. On the other hand, the lesion uptake of 111In-pentetreotide varied, and not all the sites shown by other imaging modalities were visualised, probably due to differences in membrane receptor expression. In conclusion, OS can be useful in the diagnosis, follow-up and therapeutic management of neuro-endocrine tumors. Further investigations are required to assess the role of OS in other pathologies. Short title: Somatostatin receptor imaging.