Distinct Imaging Characteristics of Different Metastases From Primary Prostate Adenocarcinoma and Rectal Carcinoid Tumor on 18F-Fluciclovine and 68Ga-DOTATATE PET/CT

A 71-year-old man with history of prostate cancer is evaluated for rising prostate-specific antigen. The patient also has a history of rectal well-differentiated neuroendocrine tumor. On F-fluciclovine PET/CT, 2 retroperitoneal lymph nodes exhibited intense fluciclovine avidity, whereas one enlarged perirectal lymph node only showed background uptake. On further Ga-DOTATATE PET/CT, the perirectal lymph node revealed intense DOTATATE avidity, whereas the 2 retroperitoneal lymph nodes only with similar to background DOTATATE avidity. Biopsy of the perirectal lymph node confirmed metastasis from neuroendocrine tumor. The distinct imaging characteristics of metastases from different primary malignancies correlated with their underlying different pathology.