111In-octreotide is superior to 123I-metaiodobenzylguanidine for scintigraphic detection of head and neck paragangliomas

In this study, we evaluated the diagnostic yield of somatostatin receptor scintigraphy (SRS), 1-metaiodobenzylguanidine (MIBG) scintigraphy, and morphologic imaging (CT or MRI) in patients with head and neck paragangliomas. Methods: In a university hospital setting, patients considered to have head and neck paraganglioma were referred to the outpatient endocrinology department and underwent CT or MRI, SRS, and MIBG imaging. For validation, we used a composite reference standard consisting of clinical and histologic data and CT or MRI, with which SRS and MIBG imaging were compared. Urinary metanelphrine and normetanephrine measurements were also obtained. Results: Twenty-nine consecutively referred patients (17 women and 12 men) were included and were found to have paraganglioma. Both morphologic and SRS were positive in 27 patients (sensitivity, 93%, and 95% confidence interval[CI], 77%-98%, compared with the composite reference standard), whereas MIBG was positive in only 13 patients (44%; 95% CI, 23%-61%) (P < 0.001, compared with SRS). On a lesion-based analysis, morphologlic imaging detected 31 lesions (sensitivity, 82%; 95% CI, 65%92%), SRS detected 34 (89%; 95% CI, 75%-97%), and MIBG detected 15 (42%; 95% CI, 26%-59%). SRS was superior to MIBG (P = 0.001). With SRS, a previously unknown carcinoid tumor was detected in 1 patient, and a carcinoid was suspected in another patient. MIBG detected an additional adrenal pheochromocytoma in 1 patient. Urinary metanephrine or normetanephrine excretion was elevated in 6 patients. The number of lesions on SRS and MIBG per patient correlated with the levels of abnormal metanephrine or normetanelphrine excretion (P = 0.005 and P = 0.02, respectively). Conclusion: SRS was superior to MIBG in patients with highly suspected head and neck paraganglioma.