Gadolinium-Based Contrast Agents

Background

NoteInto what three categories can gadolinium-based contrast agents be divided?

Gadolinium-based contrast agents (GBCAs) are divided into three categories based on their stability and carrier molecule (also called chelating agent): ionic linear, nonionic linear, and nonionic macrocyclic.

GBCAs consist of the combination of the gadolinium ion to its carrier molecule.

The carrier molecule serves to minimize the toxicity of gadolinium in its free form while preserving its contrast properties.

NoteWhen comparing macrocyclic and linear GBCAs, which takes a shorter amount of time for dissociation of “free” gadolinium?

When compared to macrocyclic GBCAs, linear GBCAs have a lower kinetic stability rate, meaning they take a shorter amount for the dissociation of “free” gadolinium.

This is because the macrocyclic form cages the gadolinium ion leading to better protection while the linear form is an open flexible chain with weaker protection.

However, despite their lower stability, linear GBCAs seem to cause less adverse reactions than macrocyclic GBCAs.

NoteBetween linear and macrocylclic GBCAs, which seem to cause less adverse reactions?

Despite their lower stability, linear GBCAs seem to cause less adverse reactions than macrocyclic GBCAs.

NoteWhere is gadolinium found in nature?

Gadolinium is a rare earth element—that does not exist in nature in its pure form due to its high reactivity—and can be extracted from minerals such as monazite and bastnaesite.

NoteWhich GBCAs are used when imaging of the hepatobiliary tree is needed? (e.g. MRCP) and why?

When imaging of the hepatobiliary tree is needed, tissue-specific GBCAs (e.g. gadoxetate disodium and gadobenate dimeglumine) are used because they are taken up by hepatocytes and later excreted into the biliary system.

Class	Generic Name (Brand Name)	Immediate Reactions per 10,000 Administrations
Linear, nonionic	Gadodiamide (Omniscan)	1.5
Linear, ionic	Gadopentetate (Magnevist), Gadoxetate (Eovist), Gadobenate (MultiHance), Gadofosveset (Ablavar)	8.3
Macrocyclic	Gadobutrol (Gadovist), Gadoterate (Dotarem), Gadoteridol (ProHance)	16

References

(Chehabeddine et al. 2019; Behzadi et al. 2018)

Behzadi, Ashkan Heshmatzadeh, Yize Zhao, Zerwa Farooq, and Martin R. Prince. 2018. “Immediate Allergic Reactions to Gadolinium-Based Contrast Agents: A Systematic Review and Meta-Analysis.” Radiology 286 (2): 471–82. https://doi.org/10.1148/radiol.2017162740.

Chehabeddine, Lara, Tala Al Saleh, Marwa Baalbaki, Eman Saleh, Samia J. Khoury, and Salem Hannoun. 2019. “Cumulative Administrations of Gadolinium-Based Contrast Agents: Risks of Accumulation and Toxicity of Linear Vs Macrocyclic Agents.” Critical Reviews in Toxicology 49 (3): 262–79. https://doi.org/10.1080/10408444.2019.1592109.