Advanced Endoscopic Ultrasound Imaging: Contrast-Enhanced Endoscopic Ultrasound (Low MI, High MI), Including 3D Techniques in Pancreatic Imaging

Abstract

Contrast-enhanced endoscopic ultrasound (CE-EUS) represents a new technique that can be used in conjunction with radial or linear EUS scopes, coupled with the corresponding ultrasound system. The technique is based on a second-generation blood-pool ultrasound contrast agent injected through a peripheral vein, which subsequently can be visualized through the microcirculation in the early arterial and late venous phase, especially when used with contrast harmonic imaging techniques (low mechanical index techniques). Contrast agents can be used as a Doppler signal enhancer (high mechanical index techniques), although this technique is particularly prone to artifacts. Both techniques can be used in conjunction with 3D acquisition modes, in order to quantify the vascularity of tumors or to better delineate the relationship with surrounding vessels. The CE-EUS techniques have been used mostly for pancreatic examinations, i.e., for the differential diagnosis of focal pancreatic masses. Thus, pancreatic adenocarcinoma has a hypovascular (hypoenhanced) appearance, whereas neuroendocrine tumors are usually hypervascular (hyperenhanced). Also, pseudotumoral chronic pancreatitis and autoimmune pancreatitis have an iso- or hypervascular appearance. All these techniques are described in the present article, with emphasis on the examination modes and technical details. This article is part of an expert video encyclopedia.