MRI of the skull – when do I need contrast medium?
An MRI examination of the skull is initially always performed without the administration of contrast medium. During the examination, the examining radiologist decides whether an injection of contrast medium via an access placed in the crook of the arm is necessary or helpful, depending on the problem and the disease. A second imaging session is then performed.
The administration of contrast medium is particularly suitable for better imaging of metabolically active structures (e.g. inflammation) with a high blood supply. The comparison between images without and with contrast agent allows a distinction to be made between fresh and old lesions, for example in multiple sclerosis. In addition, the accumulation of contrast medium is characteristic for the individual brain tumors and metastases.
This makes it easier to distinguish between them. MR angiography is a separate imaging of the vessels in the area of the head using contrast medium. It is used to identify vascular changes (e.g. stenoses, aneurysms).
When can I do without contrast medium?
MRI imaging of the skull is initially always performed without the administration of contrast medium. In some cases, these images are already significant, depending on the problem at hand, which is why it is not necessary to administer a contrast medium and repeat the imaging procedure. In patients with an intolerance to the contrast medium or in whom the contrast medium cannot be excreted via the kidneys, such as in renal dysfunction, the administration of contrast medium is not permitted.
Risks
After removing all metallic objects and clothing, there is usually no risk to the patient from the magnetic field and radio waves. In studies conducted so far, no side effects for humans could be proven. A study can therefore be repeated as often as desired and can also be used in children and in exceptional cases during pregnancy.
If the patient cannot remove all metallic objects and clothing (e.g. implants or tattoos), the treating physician must weigh up the risks and benefits of the examination. There is a risk that the effect of implants may be cancelled out by the magnetic field, or that the tattoos may cause the skin to heat up and even cause burns. Further occurring side effects are caused by the administration of a contrast medium. Even though the occurrence of side effects caused by the contrast medium is rare, temperature sensation disorders, a tingling sensation on the skin, headaches, nausea and general discomfort are possible. However, these symptoms usually do not last longer than a few hours, as the contrast medium is quickly excreted via the kidneys.
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