Clinical oncology for pancreatic and biliary cancers: Advances and current limitations.

In the early 2000s, the main stream of endoscopic ultrasonography (EUS) changed from a mechanical scanning method to electronic radial or linear scanning methods. Subsequently, useful applications in trans-abdominal ultrasonography came within reach of EUS. In particular, contrast-enhanced EUS (CE-EUS) and EUS-elastography became cutting-edge diagnostic modalities for pancreatic disorders. Each type of pancreatic disorder has characteristic hemodynamics. CE-EUS uses color Doppler flow imaging and harmonic imaging to classify pancreatic lesions. EUS-elastography can assess tissue hardness by measuring its elasticity. This parameter appears to correlate with the malignant potential of the lesions. Tissue elasticity studies can provide information on both its pattern and distribution. The former is the conventional method of morphological diagnosis, but it is restricted to observations made in a region of interest (ROI). The latter is an unbiased analysis that can be performed by image analysis software and is theoretically constant, regardless of the ROI. Though EUS-fine needle aspiration (FNA) is also a very useful diagnostic tool, there are several limitations. Diagnostic EUS-FNA of pancreatic cystic lesions has marginal utility mainly due to low sensitivity. Therefore, in particular, endoscopists should keep this limitation in mind.