Increased hardness of the underlying pancreas correlates with the presence of intraductal papillary-mucinous neoplasm in a limited number of cases.

Purpose: Pancreatic fibrosis or fibrosing reactions have been reported in intraductal papillary-mucinous neoplasm (IPMN) patients. We assessed whether a higher elastic modulus (EM) measured using shear wave elastography (SW-EG) correlated with the existence of branch-duct (BD) IPMN.

Methods: In total, 183 normal pancreas (NP) and 123 BD-IPMN cases were enrolled. First, we assessed the difference in pancreatic EM (PEM) at different sites (head or tail side of the cyst). Second, a comparison was done between the median PEM of the NP and the BD-IPMN cases. Receiver-operating characteristic analysis was performed to determine the BD-IPMN diagnostic capabilities. Finally, in patients whose cyst was not visualized, the test-positive rate was determined.

Results: No significant difference was seen between the cyst head side PEM (4.61 kPa) and the tail side PEM (5.35 kPa) (P = 0.471). Among these cases matched by age, 73 were selected each from NP and BD-IPMN cases (median age 65 years). The median PEM of the BD-IPMN cases (5.18 kPa) was significantly higher than that of the NP cases (3.17 kPa) (P < 0.001). When the cut-off value was set at 4.75 kPa, the sensitivity, specificity, PPV, NPV, and accuracy were 75.3%, 64.4%, 72.3%, 67.9%, and 69.9%, respectively. The cut-off value of 4.75 kPa helped for the indirect selection of BD-IPMN patients (10/17, 58.8%) whose cyst was not detected on B-mode ultrasonography.

Conclusion: SW-EG measurement of the underlying pancreatic parenchyma may correlate with the presence of BD-IPMN.