**1. Introduction**

The pancreas, a retroperitoneal organ, is more difficult to evaluate by ultrasound (US), mostly due to a poor acoustic window generated by the interposition of intestinal gas between the transducerandthepancreas.Inordertobeabletocorrectlyevaluatethepancreas,anexperienced operator is needed.

© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

On the other hand, US is a useful tool to identify pancreatic lesions, but ultrasound alone is not enough for the differential diagnosis and staging of the identified lesions, especially if a malignant tumor is suspected.

Contrast‐enhanced ultrasound (CEUS) is not useful for the detection of focal pancreatic lesions, either solid or liquid. It is useful for the characterization of ultrasound‐detected lesions at this level [1]. The technique can be used in acute and chronic pancreatitis (CP), in the characteri‐ zation of solid tumors: ductal adenocarcinoma or neuroendocrine tumors, in the characteri‐ zation of pseudocysts or pancreatic cystic tumors.

When a pancreatic tumor is detected, an immediate and correct differential diagnosis is mandatory to establish the appropriate management [2]. Conventional ultrasound followed by CEUS can provide a rapid assessment of the pancreatic lesion's pattern and can charac‐ terize the vascularization, thus making possible a differential diagnosis immediately after detection.

CEUS has the advantage of being a real‐time imaging method that allows continuous visual‐ ization of vascular enhancement pattern, as opposed to contrast‐enhanced (CE) computer tomography (CT) or magnetic resonance imaging (MRI), which only take snapshots at preset time moments. Due to lack of side effects and irradiation, CEUS can be repeated immediately if inconclusive.

The most frequently used ultrasound contrast agent for pancreas examination is SonoVue (Bracco SpA, Milan, Italy), a second generation, strictly intravascular contrast agent, containing sulfur hexafluoride–filled microbubbles encapsulated in a phospholipid shell. US contrast agents have no influence on micro‐vascularity and can be also used in patients with renal failure, and also allergic reactions are exceptionally rare [2, 3], as opposed to contrast‐enhanced CT/MRI [4–7].
