Feasibility of Shear wave elastography for the early diagnosis of chronic pancreatitis

(BACKGROUND)Chronic pancreatitis (CP) is difficult to be diagnosed at the early stage. Endoscopic ultrasonography (EUS) may be an apparatus for early diagnosis of CP, but the diagnosis is based on subjective criteria. Shear wave elastography (SW-EG) using transabdominal ultrasonography, which quantifies tissue elasticity as the elastic modulus, may be an objective and less invasive apparatus for the diagnosis of CP. (METHODS) From October 2012 to October 2014, 90 cases known or suspected as CP who underwent EUS and SW-EG were included in this study. SW-EG was measured at five times in the pancreatic parenchyma and the median value was defined as pancreatic elastic modulus (PEM). All cases were categorized in 4 stages using EUS-based criteria for the diagnosis of CP (Rosemont classification). (RESULTS) PEM (median, IQR) of consistent with CP (n=33), suggestive of CP (n=18), indeterminate for CP (n=15), and normal (n=24) were 8.7(7.3) kPa, 7.8(6.0) kPa, 6.9(1.8) kPa, 3.2(3.2) kPa, respectively, with significant difference among each stage (P<0.001). There was a significant positive correlation between PEM and CP stage (rs = 0.55, P<0.001). Areas under the receiver operating characteristic curve for the accuracy of SW-EG (all stages of CP vs. normal) was 0.84 (sensitivity 78.5%, specificity 79.1%). (CONCLUSION) CP can be diagnosed by SW-EG non-invasively and objectively without performing EUS at the early stage.