“How to perform contrast-enhanced ultrasound (CEUS)” provides general advice on the use of ultrasound contrast agents (UCAs) for clinical decision-making and reviews technical parameters for optimal CEUS performance. CEUS techniques vary between centers, therefore, experts from EFSUMB, WFUMB and from the CEUS LI-RADS working group created a discussion forum to standardize the CEUS examination technique according to published evidence and best personal experience. The goal is to standardise the use and administration of UCAs to facilitate correct diagnoses and ultimately to improve the management and outcomes of patients.

Moderately differentiated HCC generally shows classic enhancement features, while well- and poorly differentiated tumors account for most atypical variations. Extended observation in the portal phase is important as late washout occurs with slightly more frequency than washout in the conventionally defined portal venous phase.

Contrast-enhanced ultrasound (CEUS) is a specialized form of ultrasound (US) performed with an intravenous injection of microbubble contrast agents. It has been successfully used for a variety of applications including characterization of liver tumors. In April 2014, the American College of Radiology (ACR) convened a working group of international experts to develop ACR CEUS Liver Imaging Reporting and Data System (CEUS LI-RADS). An initial version of CEUS LI-RADS was published in August 2016. Although the CEUS LI-RADS concept and principles for liver lesion characterization, using dynamic contrast enhancement features, are similar to those for CT or MRI, there are significant differences between CT/MRI and CEUS LI-RADS. Therefore, CEUS LI-RADS has different diagnostic features and a unique characterization algorithm. The size of a lesion, the type and degree of arterial phase enhancement, the presence of washout, and the timing and degree of washout are the major features used for categorization. This paper describes key differences between CT/MRI and CEUS, and provides a diagnostic algorithm of CEUS LI-RADS with detailed, step-by-step instructions and imaging examples of CEUS LI-RADS categories.

Follow-up multiphase helical CT of HCCs treated with percutaneous RF ablation showed variable findings in the treated lesions and surrounding liver parenchyma.

Autoimmune pancreatitis is the pancreatic manifestation of IgG4-related sclerosing disease, which recently was recognized as a distinct disease entity. Numerous extrapancreatic organs, such as the bile ducts, gallbladder, kidneys, retroperitoneum, thyroid, salivary glands, lung, mediastinum, lymph nodes, and prostate may be involved, either synchronously or metachronously. Most cases of autoimmune pancreatitis are associated with elevated serum IgG4 levels; extensive IgG4-positive plasma cells; and infiltration of lymphocytes into various organs, which leads to fibrosis. There are several established diagnostic criteria systems that are used to diagnose autoimmune pancreatitis and that rely on a combination of imaging findings of the pancreas and other organs, serologic findings, pancreatic histologic findings, and response to corticosteroid therapy. It is important to recognize multiorgan involvement of IgG4-related sclerosing disease and be familiar with its clinical and imaging features because it demonstrates a favorable response to treatment.

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Medical imaging plays an important role in the diagnosis and management of hepatocellular carcinoma (HCC). The Liver Imaging Reporting and Data System (LI-RADS) was initially created to standardize the reporting and data collection of CT and MR imaging for patients at risk for HCC. As contrast-enhanced ultrasound (CEUS) has been widely used in clinical practice, it has recently been added to the LI-RADS. While CEUS LI-RADS shares fundamental concepts with CT/MRI LI-RADS, there are key differences between the modalities reflecting dissimilarities in the underlying methods of image acquisition and types of contrast material. This review introduces a recent update of CEUS LI-RADS and explains the key differences from CT/MRI LI-RADS.

Four categories of discordance were identified, one of which is unexplained. Contrast agent diffusion caused portal venous phase discordance in malignant tumors (n = 6) whereby CT and MRI contrast material diffused through the vascular endothelium into the tumor interstitium, concealing washout. Sonographic microbubbles were purely intravascular and showed washout. Arterial phase timing discordance occurred in metastatic lesions (n = 10) with hypervascularity and rapid washout on contrast-enhanced sonography. CT arterial imaging performed later showed hypovascularity. Rapidly enhancing hemangiomas (n = 7) exhibited hypervascularity on CT when contrast-enhanced sonography also showed peripheral nodules and fast centripetal progression. Discordance caused by fat in lesions (n = 4) or liver (n = 10) reflected the inherent echogenicity of fat on sonography compared with its low attenuation on CT and low signal intensity on MRI. Infrequent cases of discordance remain unexplained. Recognition of the cause of the infrequent disagreement in enhancement patterns on contrast-enhanced sonography with those on CT and MRI improves diagnostic interpretation.