Techniques of image enhancement in EUS (with videos)

p Since its introduction to clinical practice in the 1980s, EUS has been progressively used to stage and diagnose pancreaticobiliary and GI benign and malignant disorders. Comparison studies have shown that EUS is more accurate than transabdominal US, CT, and magnetic resonance imaging in the detection and staging of GI and extraluminal lesions.1-3 In addition, EUS-guided FNA (EUS-FNA) is a well-established technique allowing for tissue sampling whenever indicated.4 However, EUS presents a few limitations. First, it is very operator dependent. Second, it requires high levels of training and a high yearly volume of examinations to maintain adequate diagnostic skills.5 Third, biliary stents and chronic pancreatitis act as confounding factors limiting EUS accuracy in pancreaticobiliary exploration.6,7 The same limitations may hamper EUS-FNA accuracy, too.8-11 To limit EUS shortcomings, researchers have used several techniques of image enhancement. These imaging techniques will hopefully make EUS less operator dependent, predict the histologic nature of the lesions before EUS-FNA, and allow more reliable assessment of malignant infiltration. The purpose of this review is to describe the methodology of the available techniques and to put them in the appropriate clinical context.