Octreotide scintigraphy for the detection of paragangliomas.

Paragangliomas have neuroendocrine characteristics. We previously described successful in vivo visualization of various tumors of neuroendocrine origin after injection of the radiolabeled somatostatin analogue octreotide. In this study, we report the results of 111In-octreotide scintigraphy in 34 patients referred because of known paragangliomas or in whom a paraganglioma was suspected and compared the results of octreotide scintigraphy with the outcomes of other imaging techniques used in the diagnosis or follow-up of these patients. Fifty of 53 (94%) known localizations in 25 patients with paragangliomas were visualized. In two patients, three localizations were missed during octreotide scintigraphy. Unexpected additional paraganglioma sites, not detected or not investigated with conventional imaging techniques, were found in 9 of 25 patients (36%) with known paragangliomas. In four of them, the supposed tumor localizations were thereafter also demonstrated with other imaging modalities. In eight of nine patients who were referred because of symptoms consistent with paraganglioma or follow-up after surgical removal of a paraganglioma, neither routine imaging nor octreotide scintigraphy revealed any abnormalities indicative of paraganglioma. We conclude that: (1) virtually all paragangliomas can be visualized using in vivo 111In-octreotide scintigraphy and (2) because conventional imaging is usually limited to the site where a paraganglioma is clinically suspected, octreotide scintigraphy, because of the information it provides on potential tumor sites in the whole body, may be useful in detecting multicentricity or metastases in patients with paraganglioma.