Diagnostic performance of [124I]m-iodobenzylguanidine PET/CT in patients with pheochromocytoma.

123/131I-MIBG scintigraphy has shown a high specificity for imaging pheochromocytoma and paraganglioma however with low sensitivity due to low spatial resolution. 124I-MIBG PET may overcome this limitation to improve the staging of patients with (suspected) pheochromocytoma. Methods: We analyzed the sensitivity, specificity, positive and negative predictive values (PPV, NPV) of 124I-MIBG PET in 43 consecutive patients with suspected (recurrence of) pheochromocytoma using histopathological (n = 25) and clinical validation (n = 18) as standard of truth. Furthermore, we compared 124I-MIBG PET versus contrast enhanced CT (CE-CT) per-patient and per-lesion detection rate of 124I-MIBG PET in 13 additional patients with known metastatic malignant pheochromocytoma (MMP). Results: 124I-MIBG PET/CT was positive in 19/43 (44%) patients with suspected pheochromocytoma. Presence of pheochromocytoma was confirmed in 22/43 (51%). 124I-MIBG PET/CT sensitivity, specificity, PPV, NPV were 86%, 100%, 100%, 88%, respectively. 124I-MIBG PET was positive in 11/13 (85%) MMP patients. Combined 124I-MIBG PET and CE-CT detected 173 lesions, of which 166 (96%) and 118 (68%) were visible on 124I-MIBG PET and CE-CT, respectively. Discussion: 124I-MIBG PET detects pheochromocytoma with high accuracy at initial staging and high detection rate at re-staging. Superior diagnostic performance aids guidance of surgical and medical management including personalized 131I-MIBG therapy.