New Techniques in EUS: Real-Time Elastography, Contrast-Enhanced EUS, and Fusion Imaging

Endoscopic ultrasound (EUS) evolved recently through the development of EUS elastography, contrast-enhanced EUS, and fusion EUS imaging. Although EUS-guided fine needle aspiration improved through the introduction of new needle types, the sensitivity and accuracy are still not perfect, with false-negative cases encountered during the initial diagnostic approach of the patients with focal pancreatic masses. Real-time sonoelastography allows estimation of tissue strain during tissue compressions induced by vessel pulsations or respiratory movements. Published data support the added value of EUS elastography for the differential diagnosis of benign and malignant focal pancreatic masses, despite the high sensitivity but low specificity of the technique. Contrast-enhanced EUS seems to be more promising, and it has become an established indication for discrimination of focal pancreatic masses (especially hypoenhancing pancreatic adenocarcinoma as compared to isoenhancing or hyperenhancing mass-forming chronic pancreatitis or neuroendocrine tumors). Usage of contrast-enhanced EUS was also suggested for the differential diagnosis of pseudocysts and cystic pancreatic tumors, as well as for targeting of hyperenhanced viable areas as opposed to nonenhanced areas consisting of debris and mucus. Other techniques like tridimensional (3D) EUS or fusion imaging (with computed tomography or magnetic resonance imaging) are still not used in the daily clinical practice algorithms; although several studies highlighted their possible role for the management of difficult cases.