Indication
The administration of contrast medium during an MRI serves to improve the representation of structures such as arteries and veins. It helps to assess the function of an organ and supports the search for spatial demands such as tumors. There are different types of contrast media that can be used in magnetic resonance imaging (MRI). There are contrast agents that are injected and contrast agents that can be swallowed or introduced via a probe to provide a better picture of the gastrointestinal tract. You can find a lot of general information about magnetic resonance imaging under our topic: MRI
Is that dangerous?
The most common contrast media that are injected contain gadolinium (chemical element), which belongs to the so-called “rare earths”. It leads to a brighter contrast of, for example, blood vessels, tumors or the kidneys and urinary tract, since it is excreted via the kidneys. Gadolinium is actually poisonous, but for the examination it is bound to carrier substances that render it harmless.
Less frequently, iron oxide nanoparticles are used in MRIs of the liver, for a darker contrast in the liver, making metastases, tumors or other structures appear lighter, or manganese compounds for questions related to the liver or pancreas. Contrast media that are swallowed often also contain gadolinium or iron oxide nanoparticles. But pineapple or berry juices with high iron/manganese content can also be responsible for a brighter contrast in the gastrointestinal tract.
In rare cases – as with all drugs or medical interventions – side effects of contrast medium administration can occur. These mainly include allergic reactions to the contrast medium or its components. In patients with impaired kidney or liver function, serious complications can occur (see below), which is why the administration of contrast medium is generally ruled out in these patients.
Risks
Although MRI is considered a low-radiation alternative to CT (tomography), the latest findings show that gadolinium may be deposited and accumulated in the brain after four doses. It is not yet known whether this is harmful or leads to long-term damage. It cannot be excluded that the deposits could lead to neurodegenerative diseases such as dementia.
For this reason, the indication for an MRI examination with contrast medium should be very narrowly defined. Extremely rarely, gadolinium can lead to a serious, untreatable connective tissue disease, the so-called nephrogenic systemic fibrosis (NSF), due to a disturbed kidney or liver function or after a liver/kidney transplantation. This is a pathological proliferation of the connective tissue of the skin, the internal organs and the musculature.
Joints can lose their mobility and in the worst case the disease can lead to death. Men and women are equally affected. So far, only 315 cases are known worldwide.
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