The role of 68Ga-DOTATATE PET/CT in suspected neuroendocrine tumors

Objectives In patients with suspected but yet not localized neuroendocrine tumors (NET) early diagnosis or reliable exclusion is crucial for optimal individual prognosis and therapy. Despite recourse to several imaging modalities, the definite diagnosis of NET can be challenging. Therefore, we tested 68Ga-DOTATATE PET/CT as a tool for improved diagnosis in a cohort of patients with suspected, non-localized NET.

Methods 68Ga-DOTATATE PET/CT recordings were obtained in 104 consecutive patients meeting at least one of the following criteria: clinical suspicion of NET (n=70), elevated blood levels of tumor markers (n=49), and image-based suspicion of NET (n=53). Presence of NET was validated by histopathology (n=49) or clinical follow-up of 107 ± 59 weeks (n=55).

Results In 36/104 patients (35%) NET was histologically verified, most frequently located in the small bowel (10/36), pancreas (8/36), lung (5/36), and stomach (2/36). Twelve patients had tumors of non-neuroendocrine origin, and seven patients had benign tumors. 68Ga-DOTATATE PET/CT identified NET in 29 of the 36 cases, and excluded the presence of a NET in 61 of the 68 non-NET patients, indicating sensitivity of 81% and specificity of 90%. The PET/CT gave a false positive result in seven patients, and a false negative in another seven patients, indicating positive and negative predictive values of 81% and 90%, and an accuracy of 87%. Chromogranin A levels were significantly higher in both PET positive patients (1841 versus 342 ng/ml; P<0.05) and patients with verified NET (2214 versus 524 ng/ml; P<0.05).

Conclusions In patients with suspected neuroendocrine tumors due to clinical symptoms, elevated levels of tumor markers or present undetermined tumors suspicious for NET, 68Ga-DOTATATE PET/CT is highly accurate, thus substantiating its use in clinical routine diagnostics