A comparison of the performance of 68 Ga-DOTATATE PET/CT and 123 I-MIBG SPECT in the diagnosis and follow-up of phaeochromocytoma and paraganglioma

Purpose To compare the sensitivity of 123 I-metaiodobenzylguanidine (MIBG) SPECT and 68 Ga-DOTATATE PET/CT in detecting phaeochromocytomas (PCC) and paragangliomas (PGL) in the initial diagnosis and follow-up of patients with PCC and PGL disease. Methods Retrospective analysis of 15 patients with PCC/PGL who had contemporaneous 123 I-MIBG and 68 Ga-DOTATATE imaging. Results Of the 15 patients in the series, 8 were concordant with both modalities picking up clinically significant lesions. There were no patients in whom both modalities failed to pick up clinically significant lesions. There was discordance in seven patients: 5 had positive 68 Ga-DOTATATE and negative 123 I-MIBG, and 2 (12 and 14) had negative 68 Ga-DOTATATE and positive 123 I-MIBG. Utilizing 123 I-MIBG as the gold standard, 68 Ga-DOTATATE had a sensitivity of 80 % and a positive predictive value of 62 %. The greatest discordance was in head and neck lesions, with the lesions in 4 patients being picked up by 68 Ga-DOTATATE and missed by 123 I-MIBG. On a per-lesion analysis, cross-sectional (CT and MRI) and 68 Ga-DOTATATE was superior to 123 I-MIBG in detecting lesions in all anatomical locations, and particularly bony lesions. Conclusion First, 68 Ga-DOTATATE should be considered as a first-line investigation in patients at high risk of PGL and metastatic disease, such as in the screening of carriers for mutations associated with familial PGL syndromes. Second, if 123 I-MIBG does not detect lesions in patients with a high pretest probability of PCC or PGL, 68 Ga-DOTATATE should be considered as the next investigation. Third, 68 Ga-DOTATATE hould be considered in preference to 123 I-MIBG in patients in whom metastatic spread, particularly to the bone, is suspected.