⁶⁸Ga-DOTATATE PET/CT Capabilities in Diagnosing of Neuroendocrine Tumors Recurrence

Abstract

   Relevance: Timely detection and assessment of the prevalence of pancreatic neuroendocrine tumors (p-NETs), visualization of the status of somatostatin receptors, along with morphological characteristics, fundamentally affects the tactics of treatment and long-term prognosis. In recent years, a highly specific diagnostic method 68Ga-DOTATATE PET/CT has become available in Russia.   Purpose: Evaluation of the effectiveness of  68Ga-DOTATATE PET/CT in staging and detection of p-NETs recurrence in comparison with routine visualization methods.   Material and methods:  68Ga-DOTATATE PET/CT was enrolled in 55 patients diagnosed with p-NETs. Information on previous treatment was studied, as well as reports and images of CT and MRI performed no earlier than 2 months before PET/CT. In all patients, we counted foci of pathological accumulation (FPA) of  68Ga-DOTATATE, both the total number and their distribution in various organs and anatomical zones. The number of FPA on PET/CT was compared with the number of metastases on CT and MRI. Verification of FPA was carried out by follow up PET/CTs, as well as histological examination of the surgical material obtained after the resection of tumor foci after PET/CT.   Results: Out of 55 patients, FPA were detected in 48 (87.3 %). Metastases were observed on CT and MRI in 36 patients (65.5 %).  68Ga-DOTATATE PET/CT compared with previous CT and MRI helped to identify an additional 12 people with tumor lesions. The localization of the tumor process on PET/CT completely coincided with CT and MRI in 21 patients. In five patients, the malignant process on PET/CT was detected in the same anatomical areas or lymph nodes as on CT and MRI, but additional foci were detected in these areas. In seven patients, PET/CT revealed distant lung, small pelvis and bone metastases, which were not detected earlier. Secondary isolated liver lesions were detected on CT and MRI in 10 patients. PET/CT revealed additional metastases in lymph nodes and bones in three of them. Secondary lymph node lesions on PET/CT was registered in 24 patients. On CT and MRI in 13 (diameter ≥10 mm). According to CT and MRI, metastases were detected only in the abdomen in 34 patients. PET/CT data matched in 20 (58.8 %) of them. In 14 patients (41.2 %): additional foci were found in the liver, lymph nodes, pelvis and bones. Lung metastases were detected on CT and PET/CT only in one case. Bone lesions on PET/CT were noted in eight patients, on CT and MRI in two. In four patients, primary multiple neuroendocrine tumors of other localizations (small, large intestine, kidney) were detected. Another four patients had multiple p-NETs.   Conclusion:  68Ga-DOTATATE PET/CT makes a significant contribution to the assessment of the p-NETs prevalence, allows optimizing the tactics of antitumor treatment.