Advances in Endoscopic Ultrasonography Technology for Measurement of Tissue Elasticity

Endoscopic ultrasonography (EUS) is an efficient and reliable diagnostic modality for digestive diseases due to its high spatial resolution. Therefore, conventional EUS is useful to detect early pancreatic lesions. Moreover, EUS is an important imaging modality to detect early morphologic changes in chronic pancreatitis (CP). An EUS-based method is used to diagnose CP worldwide. Moreover, conventional EUS is an important method for the diagnosis of early-stage CP. However, diagnosis using conventional EUS is operator-dependent, and an approach that allows more objective diagnosis is needed. In this regard, EUS technology for measurement of tissue elasticity facilitates diagnosis. There are different methods such as strain elastography, shear-wave elastography, and measurement of optimal ultrasound speed. Strain elastography is useful for differential diagnosis of solid pancreatic lesions, malignant lymph nodes, CP, and gastrointestinal subepithelial lesions. Shear-wave elastography is useful for diagnosis of CP and liver cirrhosis. Measurement of optimal ultrasound speed is useful for diagnosis of CP. A strong advantage of EUS is its ability to evaluate elasticity noninvasively. This review describes the methods and their usefulness in various diseases.