This educational talk provides a broad overview of gadolinium based contrast agents (GBCA) for MRI with a focus on the types of gadolinium chelators, toxicity concerns with a focus on nephrogenic systemic fibrosis (NSF), as well as potential applications for specific GBCA. Although numerous MRI contrast agents have been developed, this talk will focus on those that are clinically available to inform radiologists of potential clinical applications for GBCA.
Joseph Ippolito, M.D., Ph.D.
ippolitoj@wustl.edu
Session: Body MRI: Optimize Your Clinical Practice
Highlights:
1. Gadolinium-based contrast agents (GBCA) are grouped into pharmacologic classes by the chelation agent that binds the gadolinium ion.
2. Adverse events have been associated with GBCA, namely nephrogenic systemic fibrosis (NSF).
3. GBCA are contraindicated for end stage renal disease, and renal screening is necessary for patients.
4. Two classes of clinically-available GBCA include extracellular and hepatobiliary contrast agents and can be used for a variety of applications.
Talk Title: MR Contrast Agents and their Applications
Target Audience: This syllabus is aimed at radiologists in training as well as radiologists in clinical practice who perform contrast-enhanced MRI studies. Objectives:
1. Understand the classification of chelation agents used gadolinium-based contrast agents (GBCA).
2. Understand basic concepts of gadolinium toxicity and nephrogenic systemic fibrosis.
3. To identify specific clinical applications for different GBCA.
Purpose:
To provide a basic overview of the types of GBCA and guide the appropriate selection of GBCA’s to answer specific clinical questions.
Methods:
A literature review was conducted to identify key concepts of GBCA that are relevant to the clinical radiology field, focusing on mechanisms of action, toxicity, and clinical applications.
Results:
1. Cyclic chelates are generally more stable than linear chelates and ionic chelates are generally more stable than non-ionic chelates.
2. Less stable GBCA chelators (i.e. linear and non-ionic) are more likely to result in gadolinium deposition in tissues.
3. Although potentially multifactorial, nephrogenic systemic fibrosis (NSF) has been linked to GBCA administration in patients with renal failure. Thus, renal screening is necessary for patients and multiple guidelines exist to manage these patients.
4. The majority of clinically-available GBCA are grouped into extracellular agents (e.g. gadoterate meglumine and gadoversetamide) and hepatobiliary agents (e.g. gadoxetate disodium and gadobenate dimeglumine).
5. Extracellular GBCA are used for most applications requiring contrast agents including angiography and tumor imaging. Hepatobiliary GBCA can be used for liver lesion characterization and detection as well as evaluation of the biliary system.
Discussion:
Contrast agents are necessary for a variety of MRI studies. Of the many types of MRI contrast agents, GBCA represent the vast majority of clinically available contrast agents. Therefore, it is essential that clinical radiologists know the fundamentals underlying the mechanism of action of GBCA as well as potential toxicity concerns and adverse events associated with these agents. Knowing the different types of GBCA and their applications will inform the radiologist to select the most appropriate agent for a given examination.
Conclusion:
GBCA are an essential component of many MRI examinations. Each GBCA has a unique chemical structure and associated toxicity profile. Understanding the advantages and disadvantages of each GBCA will allow the radiologist to make informed decisions as to the selection of the most appropriate contrast agent for the patient examination.
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