Contrast enhancement and elastography in endoscopic ultrasound: an overview of clinical applications in pancreatic diseases.

Endoscopic ultrasound is a �� � � � � -very accurate imaging technique with a relevant clinical impact in the diagnosis and staging of various conditions such as pancreaticobiliary lesions, esophageal cancer, lung cancer, submucosal lesions and lymph nodes. Despite its increasing importance in everyday clinical routine, endoscopic ultrasound outcomes are still highly operator-dependent and tissue confirmation with fine needle aspiration is very often required for definitive differential diagnosis of tumors. Several techniques of image enhancement have been developed in recent years in the attempt to make the technique less operator-dependent. Among them the most important appear to be contrast harmonic-endoscopic ultrasound and endoscopic ultrasound-elastography. Contrast harmonic-endoscopic ultrasound is performed with a dedicated harmonic which displays the fine vascular network of both normal and pathological tissues after injection of an ultrasound contrast agent. Endoscopic ultrasound-elastography displays with different colors the differences in hardness between tissues, thus estimating elasticity in soft normal tissues which appear red and hard neoplastic tissues which appear blue. While contrast harmonic-endoscopic ultrasound has been introduced into clinical practice, endoscopic ultrasound-elastography mainly represents an investigational tool. The purpose of this paper was to review the mechanism of action and the clinical outcomes of contrast harmonic-endoscopic ultrasound and endoscopic ultrasound-elastography in pancreatic diseases. Both 353techniques show promising applications in the study of pancreatic tumors including differential diagnosis and providing guidance to fine needle aspiration.