Duration | MRT for a torn meniscus

Duration

The examination takes a maximum of 20 minutes. There is also time for clarification and preparation and possibly waiting time on site.

The use of contrast media

The MRI examination does not necessarily involve the use of contrast agents. The use of certain contrast agents (KM) depends entirely on the problem at hand. The reason behind this is that some structures are displayed in similar gray levels without contrast media, which can be a hindrance to the diagnosis.

The administration of a contrast agent can improve the color gradation, since different tissue structures absorb and accumulate the CM to a different extent, thus increasing the contrast. Tissue areas that absorb the KM particularly well are thus brighter. There is also a further difference between “whitening/lightening” and “darking/blackening” contrast agents.

However, if an area does not become lighter than expected despite the administration of KM, this may be an indication that the corresponding structure is not well supplied with blood. The KM is injected via an arm vein and should be distributed throughout the body via the bloodstream. The menisci are subdivided into 3 zones depending on the blood flow so that a changed blood flow can be detected in the MRI.

A very frequently used contrast medium is gadolinium. Without an additive, gadolinium is toxic and can accumulate in organs such as the liver, bones or spleen. It is therefore essential to add an acid called DTPA.

The elimination of the contrast medium is then carried out via the kidney. Occasionally there may be incompatibilities with the contrast medium. Patients who are prone to allergies should inform their attending physician about this in any case.

Contraindications

The general contraindications apply as for any MRI. Implants such as pacemakers or cochlear implants are considered contraindications. Endoprostheses such as hip TEPs (total replacement of the hip joint) and screw or plate material are usually made of titanium, which is compatible with the MRI, but may heat up during a long examination and lead to artifacts, i.e. disturbances on the image.

Pregnant women should not have an MRI during early pregnancy, as it is not clear whether this can cause damage to the fetus. Other metal parts, such as metal splinters after accidents, are also considered a contraindication for the examination. For patients with fear of confined spaces (claustrophobia), the MRI examination of the knee should be bearable, since the head and most of the body are not in the MRI tube. When contrast medium is administered, allergic reactions can occur very rarely and contrast medium should not be given if the kidney and liver values are poor.