68Ga-DOTATATE PET/CT in the diagnosis of recurrent neuroendocrine tumors

Objectives There is no consensus about the optimal follow-up examinations after curative resection of neuroendocrine tumors (NET). Inconclusive results obtained from different imaging modalities often complicate patient management and cause discomfort to the patients. Therefore, we evaluated 68Ga-DOTATATE PET/CT for the detection of NET recurrence.

Methods 70 patients (37 male, mean age 58 years) in the follow-up after curative resection of primary NET were examined with 68Ga-DOTATATE PET/CT. The primary tumor was located in the small bowel (n=56), colon (n=8), stomach (n=3) or thyroid (n=3). 27/70 patients had elevated levels of Chromogranin A or NSE at the time point of PET/CT. Final diagnosis was made by histopathological verification (n=21) or clinical follow-up of mean 104 weeks (n=49).

Results In 31 patients (44%) presence of NET recurrence was verified by histopathology or follow-up examinations. Most frequently the metastases of the recurrent NET were located in the liver (n=14), lymph nodes (n=8), lung (n=4), bones (n=3), soft tissue (n=3) or presented as local recurrence (n=14). Three patients had tumors of non-neuroendocrine origin (each one non-Hodgkin lymphoma, signet-ring carcinoma and colorectal cancer). 68Ga-DOTATATE PET/CT identified NET recurrence in 28/31 patients, and excluded the presence of a recurrent NET in 33/39 patients, indicating sensitivity of 90% and specificity of 85%. The PET/CT gave a false positive result in six patients, and a false negative in another three patients, indicating positive and negative predictive values of 82% and 92%, and an accuracy of 87%.

Conclusions In patients` follow-up after curative resection of a NET 68Ga-DOTATATE PET/CT is highly accurate, thus substantiating its use in clinical routine diagnostics