Endoscopic ultrasound elastography

Endoscopic ultrasound (EUS) is a reference technique for diagnosing and staging several different diseases. EUS-guidedbiopsies and fine needle aspirations are used to improve diagnostic performance of cases where a definitive diagnosis cannotbe obtained through conventional EUS. However, EUS-guided tissue sampling requires experience and is associated with alow but not negligible risk of complications. EUS elastography is a non-invasive method that can be used in combination withconventional EUS and has the potential for improving the diagnostic accuracy and reducing the need for EUS-guided tissuesampling in several situations. Elastography measures tissue stiffness by evaluating changes in the EUS image before and afterthe application of slight pressure to the target tissue by the ultrasonography probe. Pathologic processes such as cancerizationand fibrosis alter tissue elasticity and therefore induce changes in elastographic appearance. Qualitative elastography depictstissue stiffness using different colors, whereas quantitative elastography renders numerical results expressed as a strain ratio orhue histogram mean. EUS elastography has been proven to differentiate between benign and malignant solid pancreatic masses,as well as between benign and malignant lymph nodes with a high accuracy. Studies have also demonstrated that the earlychanges of chronic pancreatitis can be distinguished from normal pancreatic tissues under EUS elastography. In this article, wereview the technical aspects and current clinical applications of qualitative and quantitative EUS elastography and emphasizethe potential additional indications that need to be evaluated in future clinical studies.