Neuroendocrine tumor recurrence: diagnosis with 68Ga-DOTATATE PET/CT.

PURPOSE: To evaluate diagnostic performance of gallium 68-tetraazacyclododecane tetraacetic acid-octreotate ((68)Ga-DOTATATE) in detection of recurrent neuroendocrine tumors (NETs).
MATERIALS AND METHODS: Approval was waived by the local ethics committee for this retrospective study. Between 2007 and 2011, 63 patients (mean age, 58 years) were examined with (68)Ga-DOTATATE positron emission tomography (PET)/computed tomography (CT) after primary NET curative resection. Reasons for PET/CT were regular follow-up examinations (n = 30), increased plasma levels of tumor markers (n = 27), or clinical suspicion of recurrence (n = 6). Final diagnosis was determined with histopathologic verification (n = 25) or clinical follow-up (n = 38). PET/CT scans were evaluated in consensus by two readers without blinding to clinical information and independently by two readers with blinding. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated.
RESULTS: Final diagnosis of NET recurrence was determined in 29 patients. In three other patients, tumors of nonneuroendocrine origin were diagnosed. (68)Ga-DOTATATE PET/CT helped identify NET recurrence in 26 of 29 patients (sensitivity, 90%) and exclude presence of recurrent NET in 28 of 34 patients (specificity, 82% ). PET/CT provided false-positive and false-negative results in six and three patients (PPV, 81% [26 of 32]; NPV, 90% [28 of 31]; accuracy, 86% [54 of 63]). In gastroenteropancreatic NET (n = 45), sensitivity was 94% (17 of 18); specificity was 89% (24 of 27); PPV was 85% (17 of 20); NPV was 96% (24 of 25); and accuracy was 91% (41 of 45). Two blinded readers achieved sensitivity of 79% (23 of 29) and 76% (22 of 29); specificity of 85% (29 of 34) and 94% (32 of 34) (κ = 0.80); and accuracy of 83% and 86%.
CONCLUSION: (68)Ga-DOTATATE PET/CT is accurate in detection of recurrent NET. Blinded PET/CT review markedly decreased sensitivity, underlining importance of considering clinical parameters in NET recurrence. Present results must be further validated to substantiate use of (68)Ga-DOTATATE PET/CT in routine follow-up after curative resection of NET. © RSNA, 2013