Usefulness of shear wave elastography as a quantitative diagnosis of chronic pancreatitis

Background and Aim: Chronic pancreatitis (CP) is sometimes diagnosed at the progressed stage. For the early diagnosis of CP, endoscopic ultrasonography (EUS) may be a useful method, but its diagnostic criteria is based on subjective judgment. Shear wave elastography (SW-EG) using transabdominal ultrasonography, which quantifies tissue elasticity as an absolute value, may be an objective and noninvasive method for the diagnosis of CP. Methods: Eighty-five patients with known or suspected CP who underwent both EUS and SW-EG from October 2012 to July 2016 were included in this study. Patients were categorized into four stages using Rosemont classification and into three stages using Japan Pancreas Society clinical diagnostic criteria 2009 that was EUS-based criteria for the diagnosis of CP. SW-EG was measured five times in the pancreatic parenchyma, and the median value was defined as the pancreatic elastic modulus (PEM). Results: Pancreatic elastic modulus was significantly positively correlated with Rosemont classification stage (r_s = 0.54), Japan Pancreas Society stage (r_s = 0.41), and the number of EUS features (r_s = 0.47). Area under the receiver operating characteristic curve for the accuracy of SW-EG (consistent with CP and suggestive of CP vs normal and indeterminate for CP) was 0.77 (sensitivity 77.1%, specificity 64.9%). In a multivariate linear regression analysis including various EUS features related to PEM, hyperechoic foci with shadowing and lobularity with honeycombing were independent features related to PEM. Conclusions: Chronic pancreatitis may be diagnosed noninvasively and objectively using SW-EG without performing EUS.