Multiphase evaluation of contrast-enhanced endoscopic ultrasonography in the diagnosis of pancreatic solid lesions

Background/Objectives: Time-intensity curve (TIC) under contrast-enhanced EUS (CE-EUS) allows continuous and quantitative evaluation of targeted area in the pancreas. However, TIC is not always available and the procedure is complicated. We aimed to propose a simplified method by evaluating multiple phases of CE-EUS in the diagnosis of pancreatic solid lesions. Methods: We retrospectively reviewed 210 patients with pancreatic solid lesions including 142 with pancreatic ductal cancer (PDAC), 31 with pancreatic neuroendocrine neoplasm, 13 with solid pseudopapillary neoplasm and 24 with mass-forming pancreatitis who underwent CE-EUS and achieved final diagnoses. The CE-EUS images were continuously recorded for 60 s, and each image at 20, 40 and 60 s was used for the evaluation. The images were classified into three patterns as hypoechoic, hyperechoic and isoechoic vascular patterns compared with the surrounding pancreas, and the relevance between the multiphase evaluation of CE-EUS and each disease group was investigated. Results: In PDAC group, majority of the lesions showed hypovascular pattern at 20 or 40 s after injection of contrast medium following early enhancement. The sensitivity, specificity and accuracy of PDAC pattern in the differentiation of PDAC from other lesions was 83.1%, 86.8% and 84.3%, respectively. On histopathological analysis, significant differences were seen in histologic types, infiltration (INF), and neural invasion (ne) between those who showed PDAC pattern and those who didn't. Conclusions: Multiphase evaluation of CE-EUS is convenient and useful method for the differentiation of pancreatic solid lesions which can be alternatively used for TIC.