Contraindications
Since metal objects are a danger because they are strongly attracted by the magnetic field, patients with a pacemaker must not normally have an MRI examination. An implanted defibrillator (ICD), an artificial inner ear (cochlea implant) or metallic artificial heart valves are also contraindications for performing an MRI, as is an insulin pump. Certain factors, such as an intolerance or a restriction of renal function, speak against performing an MRI with contrast medium. During pregnancy, due to possible complications, an MRI examination should only be performed in an emergency during the first 3 months.
Complications
Since the patient is not exposed to radiation during an MRI examination of the lungs, unlike X-rays or computer tomography, complications are very rare. Tattoos (when colors contain metal parts) or make-up may cause local heating of the skin, which may show a reddening after the examination. Due to possible complications, an MRI should only be performed in the first three months of pregnancy in emergencies.
Contrast medium
In an MRI of the lung, different contrast agent options can be used depending on which structures are to be displayed. By administering contrast medium, certain structures in the body can be better visualized. MRI only provides black-and-white images, which is why different tissues are often difficult to distinguish.
A contrast medium that is injected into the vein and distributed in the bloodstream allows better imaging of blood vessels. In addition, the contrast agent accumulates to a greater or lesser extent in the various tissues, so that tumors and metastases in particular can be detected. The contrast medium that is used is generally very well tolerated and can also be used in the case of an existing allergy to X-ray contrast medium, as it does not contain iodine.
The contrast medium is excreted via the kidneys and urine. Patients with a kidney dysfunction are often not allowed to receive a contrast medium. However, the contrast medium can also be inhaled during a lung MRI. This shows very precisely how the inhaled air is distributed in the lungs, i.e. how well the lungs are ventilated. Helium is particularly suitable for this purpose.
