Hyperechoic Abnormalities of Pancreatic Parenchyma On EUS in Patient with Normal Pancreatic Duct On ERP: Are They True Or Fake?

Abstract

Background and Aim: Traditionally, the gold standard for the diagnosis of chronic pancreatitis (CP) has been either endoscopic retrograde pancreatography (ERP) and/or pancreatic function test. Recently, endoscopic ultrasonography (EUS) is considered a useful modality for the diagnosis of CP because of its ability to place the transducer in close proximity to the pancreas. Among patients with CP, EUS may reveal abnormal parenchyma in the form of hyperechoic changes, such as echogenic strands and hyperechoic foci. However, since these findings sometimes identified in patient with normal pancreatic duct on ERP, it will be confused whether it may diagnose early CP or not. The aim of this study was to investigate the implication of hyperechoic abnormalities on EUS in normal ERP. Patients and Methods: One hundred ten patients who were undergone both EUS and ERP within 2 months were enrolled, excluding in patient with pancreatic cancer, IPMN and lower biliary ductal cancer. CP was defined using the Cambridge classification of ERP findings. On EUS images, fine-reticular pattern as normal pancreatic parenchyma, and hyperechoic foci/strand as hyperechoic abnormalities were evaluated. Results: Normal/abnormal pancreatic duct on ERP was identified in 86 (78.2%) /24 (21.8%) patients, respectively. Fine-reticular pattern on EUS was seen in 76 (76/86: 88.3%)/3 (12/24: 50%) patients who had normal/abnormal ERP (p < 0.01). On the other, in 43 patients who had no EUS abnormalities, all patients (100%) were identified fine reticular pattern. Moreover, in 22 patients who had no fine-reticular pattern on EUS, all patients (100%) were identified parenchymal abnormalities. These results strongly suggested fine-reticular pattern indicated normal pancreatic parenchyma. On the basis of above findings, EUS abnormalities on normal ERP were investigated. Hyperechoic abnormalities on EUS were seen in 46 (53.7%) patients with normal ERP. In these 46 patients, fine-reticular pattern on EUS was seen in 36 patients, and none of them have become definite CP in the follow-up period. Conclusion: Hyperechoic EUS abnormalities (foci/strands) were not necessarily mean that presence of early chronic pancreatitis. Fine-reticular pattern is useful for differentiation whether hyperechoic abnormalities are true or fake.