Power Doppler Endoscopic Ultrasound for the Assessment of Pancreatic Neuroendocrine Tumors

Objective: Pancreatic neuroendocrine tumors (PNET) represent rare, heterogeneous tumors with clinical, imaging and treatment particularities. The aim of this study was to assess the role of power Doppler endoscopic ultrasound (EUS) in the diagnosis and characterization of PNET. Methods: All consecutive patients with PNET assessed by power Doppler EUS in the Research Centre of Gastroenterology and Hepatology Craiova, Romania, in the past 51 months were included in the study. All EUS examinations were performed initially in gray-scale mode, followed by power Doppler mode examinations, before and after contrast-enhancement. Each recorded EUS movie was further subjected to post-processing using a computer-enhanced dynamic analysis using a special plug-in which permitted assessment of vascularity index (EUS-VI). Results: Based on the analysis of all consecutive malignant focal pancreatic masses diagnosed in the study period, a total number of 131 consecutive patients were included: 14 patients with pancreatic neuroendocrine tumors and 117 patients with pancreatic adenocarcinoma. The sensitivity of the pre-contrast EUS-VI for the diagnosis of PNET was 71.43%, similar to EUS-FNA. After contrast enhancement, the EUS-VI is also higher in PNET (27.07%) as compared to pancreatic adenocarcinoma where it was significantly lower 9.82% (P < 0.001). However, the sensitivity of EUS-VI after contrast enhancement for the diagnosis of PNET was 100%, higher than pre-contrast EUS-VI, with an acceptable specificity (79.49%) and better accuracy (81.68%). Conclusion: Power Doppler EUS represents a useful method in the initial assessment of PNET. Using evaluation of vascularity through EUS-VI, the differentiation between PNET and pancreatic cancer could be possible, especially in the subgroup of patients where EUS-guided fine needle aspiration is falsely negative.