Differential diagnosis of solid pancreatic masses: contrast-enhanced harmonic (CEH-EUS), quantitative-elastography (QE-EUS), or both?

Background: Contrast-enhanced harmonic endoscopic ultrasound (CEH-EUS) and quantitative-elastography endoscopic ultrasound (QE-EUS) are considered useful tools for the evaluation of solid pancreatic tumors (SPT). The aim of our study was to evaluate the diagnostic accuracy of CEH-EUS, QE-EUS, and the combination of both for the differential diagnosis of SPT. Methods: Sixty-two consecutive patients (mean age 64.3 years, range 32-89 years, 44 male) who underwent EUS for the evaluation of SPT were prospectively included. EUS was performed with a linear Pentax-EUS and a Hitachi-Preirus processor. The mass (area A) and a reference area B were selected during QE-EUS, and results expressed as B/A (strain ratio). A strain histogram of the mass was also evaluated. Microvascularization of the tumor was evaluated over 2min during CEH-EUS after intravenous injection of 4.8mL SonoVue. Final diagnosis was based on histopathology of surgical specimens or EUS-guided tissue acquisition and clinical follow-up in non-operated cases. Diagnostic accuracy of CEH-EUS, QE-EUS, and their combination was calculated. Results: Median size of the masses was 32 mm (range 12-111). Final diagnosis was pancreatic adenocarcinoma (n=45), neuroendocrine tumor (n=3), inflammatory mass (n=10), pancreatic metastasis (n=2), autoimmune pancreatitis (n=1), and a mucinous cystadenocarcinoma (n=1). Overall accuracies for determination of malignancy using QE-EUS, CEH-EUS, their combination, and EUS-guided tissue acquisition were 98.4% (95% confidence interval (CI): 91.4-99.7), 85.5% (95% CI: 74.7-92.2), 91.9% (95% CI: 82.5-96.5), and 91.5% (95% CI: 83.6-99.5), respectively. Conclusion: The combination of QE-EUS and CEH-EUS is a useful tool for the differential diagnosis of SPT, giving complementary information. However, this combination does not significantly increase the diagnostic accuracy of either of the techniques performed alone.