Quantitative endoscopic ultrasound elastography: an accurate method for the differentiation of solid pancreatic masses.

Abstract

Qualitative endoscopic ultrasound (EUS) elastography is an accurate but subjective tool for the differential diagnosis of solid pancreatic masses. Second-generation EUS elastography allows quantitative analysis of tissue stiffness. We evaluated the accuracy of quantitative, second-generation EUS elastography in the differential diagnosis of solid pancreatic masses. The study included 86 consecutive patients who underwent EUS for the evaluation of solid pancreatic masses. EUS elastography was performed with the linear Pentax EUS and the Hitachi EUB900. Representative areas from the mass (A) and soft reference areas (B) were analyzed. The result of the elastographic evaluation was defined by the quotient B/A (strain ratio). Final diagnosis was based on histology of surgical specimens and cytology of EUS-fine-needle aspiration samples. The diagnostic accuracy of EUS elastography in detecting malignancy was calculated using receiver operating curve analysis. The mean size of the pancreatic masses was 31.4 ± 12.3 mm. The final diagnoses were pancreatic adenocarcinoma (n = 49), inflammatory mass (n = 27), malignant neuroendocrine tumor (n = 6), metastatic oat-cell lung cancer (n = 2), pancreatic lymphoma (n = 1), and pancreatic solid pseudopapillary tumor (n = 1). The strain ratio was significantly higher among patients with pancreatic malignant tumors compared with those with inflammatory masses. The sensitivity and specificity of strain ratio for detecting pancreatic malignancies were 100% and 92.9%, respectively (area under the receiver operating curve, 0.983). Quantitative, second-generation EUS elastography is useful for differential diagnosis of solid pancreatic masses. It allows for a quantitative and objective evaluation of tissue stiffness, which indicates the malignant or benign nature of the pancreatic lesion.