Side effects | Examination of the skull and brain using MRI

Side effects

After removing all metallic objects and clothing, there is usually no risk to the patient from the magnetic field and radio waves. The studies conducted so far have not been able to prove any side effects for humans. Any side effects that occur during or after an examination are due to the administration of contrast medium. Even though the occurrence of side effects is rare, temperature sensation disorders, tingling on the skin, headaches, nausea and general discomfort are possible. However, these symptoms do not last longer than a few hours, as the contrast medium is quickly excreted via the kidneys.

MRI with contrast medium

Since the MRI images are only displayed in black and white, many tissues look quite similar and are difficult to distinguish from each other. Here, a contrast agent helps to increase the contrast between different tissues. For example, muscles and blood vessels can be better distinguished from each other.

As a rule, the contrast medium is injected into the vein. This allows the contrast medium to be distributed in the blood and ensures that the blood vessels stand out from the rest on the MRI images. The contrast medium also accumulates in tumors and their metastases.

Therefore, in addition to tumor diagnosis, a contrast medium MRI of the head also allows the detection of brain aneurysms, brain infarcts and bleeding in the head area. MRI contrast media are very well tolerated and can also be used in the case of an allergy to X-ray contrast media, as they do not contain iodine. Gadolinium-GTPA is often used as a contrast medium.

This is a metal in combination with an acid. The contrast medium is completely excreted in the urine within 24 hours. Therefore, caution is advised in patients with severe kidney disease (renal insufficiency) as they cannot excrete the contrast medium optimally.

In very rare cases, the contrast medium can cause a change in connective tissue, a so-called nephrogenic systemic fibrosis, which affects not only the skin but also the connective tissue of the internal organs. Initially, imaging is performed without the administration of contrast agent. If the examining physician determines during these images that administration of contrast medium is necessary or helpful, the examination is briefly interrupted and the contrast medium is injected into the patient.

The contrast medium is mainly used to improve the imaging of structures with a high blood supply and metabolic activity. These are mainly centres of inflammation and some tumours. Due to the enrichment of the contrast medium, these structures appear white in the MRI image and are thus clearly distinguishable from their surroundings.

An MRI examination of the head without the use of a contraceptive agent results in almost no side effects. It can also be performed in patients with a kidney disorder or in patients with an allergy to MRI contrast medium. For some applications, MRI images without contrast agents are already very informative, but for diagnoses that require more detailed images of the blood vessels, they are often not sufficient. In tumor diagnostics, too, an MRI with contrast medium is usually performed.