Usefulness of EUS combined with contrast-enhancement in the differential diagnosis of malignant versus benign and preoperative localization of pancreatic endocrine tumors

Background Pancreatic endocrine tumors (PETs) develop in relatively few patients, but they are often difficult to diagnose because of their small size and various clinical symptoms. Objective The aim of this study was to investigate the usefulness of EUS combined with contrast enhancement (CE-EUS) in the preoperative localization of PETs and the differentiation between malignant and benign PETs. Design and Setting Single-center retrospective study. Patients Sixty-two pathologically certified PETs of 41 patients who underwent EUS, multiphasic multidetector computed tomography (MDCT), and transabdominal US at our institute since 2001. Interventions Intravenous injection of US contrast media. Main Outcome Measurements Comparison of EUS, MDCT, and US in the preoperative identification of PETs, and the characteristic findings of EUS with malignancy. Results EUS showed high sensitivity (95.1%) in identifying PETs compared with MDCT (80.6%) and US (45.2%). Multivariable logistic regression analysis showed that heterogeneous ultrasonographic texture was the most significant factor for malignancy (OR = 53.33; 95% CI, 10.79-263.58). Most heterogeneous hypoechoic areas and anechoic areas corresponded to hemorrhage or necrosis on pathologic examination. They were identified as filling defects in CE-EUS and were more clearly recognized than in conventional EUS. Limitations Retrospective study. Conclusion EUS has higher sensitivity in preoperative localization of PETs compared with MDCT and US. The characteristics of EUS and CE-EUS findings in malignant PETs were clarified, and they will improve the diagnostic accuracy of PETs.