Gadolinium retention in the brain
53 yr old female diagnosed with neurosarcoid in 2009.
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T1 imaging before and after multiple GBCA administration
Received wisdom until recently was that gadolinium contrast agents were excreted by first pass through the kidneys. Gadolinium is toxic but is considered safe as it is chelated to molecules such as DTPA. A study published recently compared post mortem specimens in 13 patients who had undergone multiple MRI studies with gadolinium contrast agents and 10 patients who had undergone multiple MRI scans without contrast administration. All patients had normal renal function. The dentate nucleui, pons, globes plaids and thalami were studied. The study group had tissue gadolinium concentrations which were dose related to the number of contrast administrations. The control group had no gadolinium within the neural tissue.
The molecular structure of the contrast agent plays a role in gadolinium retention. There are two structurally distinct classes of gadolinium based contrast agents (GBCA) - linear and macrocyclic. With the macrocyclic structure gadolinium is bound more tightly to the chelating agent and is less likely to be released as free gadolinium. Gadolinium is more 'exposed' in the linear structure.
A study comparing dentate nucleus signal intensity after previous GBCA administration in patients who had received linear GBCAs compared with patients who had received macrocyclic GBCAs show no association between dentate signal hyper intensity and macrocyclic GBCA, but a highly significant association in patients who had received linear GBCAs.
The most commonly used linear GBCA is Magnevist.
An example of a macrocyclic GBCA is Gadovist.
- McDonald RJ, McDonald JS, Kallmes DF et-al. Intracranial Gadolinium Deposition after Contrast-enhanced MR Imaging. Radiology. 2015;275 (3): 772-82. doi:10.1148/radiol.15150025 - Pubmed citation
- Kanda T, Osawa M, Oba H et-al. High Signal Intensity in Dentate Nucleus on Unenhanced T1-weighted MR Images: Association with Linear versus Macrocyclic Gadolinium Chelate Administration. Radiology. 2014; 140364. doi:10.1148/radiol.14140364 - Pubmed citation