Learning objectives
The purpose of this article is to review the basic physical principles of Contrast-enhanced ultrasound,
the technical requirements to perform it and its applications on evaluation of focal liver lesions (FLLs),
illustrated by didactic schemes and clinical cases from our practice.
Note: some of the images are displayed in a Graphics Interchange Format (GIF) - online visualization is recommended.
Background
The technique: contrast agents and physical principles
Contrast-enhanced ultrasound (CEUS) involves the use of a microbubble contrast agent during an ultrasound exam.
These microbubbles contain low soluble gases encapsulated by a shell of phospholipids,
albumin or biopolymers.
They are designed to be smaller than 7 µm (the average size of a red blood cell) and exclusively intravascular.
The gas is eliminated through the airways 10-15 minutes after administration,
without renal or hepatic metabolism.
The key property of these microbubbles is their reaction when exposed to...
Findings and procedure details
Theoretically,
CEUS can be used to evaluate any tissue studied by conventional ultrasonography.
The characterization of FLLs is CEUS’ most established indication.
Unlike convencional ultrasonography,
CEUS characterizes patterns of enhancement on arterial,
portal and late phases analogous to those shown on contrast-enhanced CT and MRI,
allowing dynamic evaluation of FLLs vascular behaviour.
As microbubbles are purely intravascular,
there is no equilibrium phase.
This explains why there are somedifferences between late enhancement patterns of CEUS and contrast-enhanced CTor MRI.
On CEUS the only determinant for the...
Conclusion
CEUS is a safe,
low-cost and readily available technique that can be performed at the bedside with no requirement for ionizing radiation and no risk of nephrotoxicity.
Although not yet a widespread technique,
evidence shows that it is cost-effective and can provide accurate diagnostic information whencharacterizing focal liver lesions.
References
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Contrast-enhanced ultrasound: what is the evidence and what are the obstacles? AJR Am J Roentgenol.
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The safety of SonoVue in abdominal applications: retrospective analysis of 23,188 investigations.
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European Medicines Agency.
European public assessment report: product information on SonoVue®.
[Last updated 20/07/2015].
Ding H,
Wang WP,
Huang BJ.
Imaging of focal liver lesions low-mechanical-index real-time ultrasonography with SonoVue.
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Wilson SR,
Burns PN.
An algorithm for the diagnosis...