Magnetic resonance imaging Procedure and contraindications for MRI
Procedure for an MRI examination What do I need to bear in mind?
Please remember to bring your referral form and, if possible, any previous findings and recordings, as well as your current blood values (creatinine) if applicable.
Before the examination begins, you must remove all metal objects. This includes smartphones, watches, hearing aids, and check and credit cards. Metal parts in the body, such as fixed dentures, joint prostheses, or metal plates following surgery, do not generally constitute contraindications. If you have a metal IUD, a gynecological check-up to check its position is recommended after the examination. Please note the contraindications listed below!
During the examination, you will lie on a table that will initially move slowly into the opening of the device, i.e., toward the magnet. You will then be either completely or partially inside the device, for example, during an examination of the knee joint.
Magnetic fields that switch on and off generate relatively loud, knocking noises that are harmless but which some patients find disturbing. You will therefore be given earplugs or closed ear protection. Depending on the area of the body being examined and the issue being investigated, the examination takes between a few minutes and half an hour. In some cases, the administration of a sedative—not a sleeping pill—can help. You should have this prescribed in advance and bring it with you to the examination. This makes MR examinations possible for almost all patients without any problems. In such cases, please remember to bring someone with you, as you will not be allowed to drive yourself after the examination.
Compared to CT, MRI is a "slow" examination. It is therefore important not to move during the examination and to follow the breathing instructions strictly. Otherwise, the images will be blurred and difficult to evaluate in some cases.
During an MRI examination, it may be necessary to inject a special contrast agent. The injection is administered into a vein. The access is established before the examination. The administration of the contrast agent is generally safe. We only use ring-shaped MR contrast agents, for which side effects have only been reported in isolated cases to date. Since the contrast agent is largely excreted by the kidneys, we need to know the creatinine level of all patients with kidney disease. The literature describes gadolinium deposits in the brain, the significance of which has not yet been fully clarified. These deposits mainly concerned linear contrast agents. We would like to emphasize that, despite millions of applications, no clinical side effects due to deposits in the brain or similar have been reported with the ring-shaped MR contrast agents we use. Skin and tissue changes, in particular NSF (nephrogenic systemic fibrosis), have been described in patients with impaired kidney function. These changes are not known to occur in patients with normal kidney function. The contrast agents we use are the latest generation of contrast agents – side effects of contrast agents are rare overall.
When is an examination problematic or not possible? Contraindications
Contraindications for an MRI examination are:
- Pacemakers, except for MR-compatible pacemakers in consultation with your cardiologist. In this case, you must make an appointment with your cardiologist shortly before the MR examination to have the pacemaker set to an MR-compatible mode, and again immediately after the MR examination.
- Cardiac implantable cardioverter defibrillator (ICD)
- Permanently implanted neurostimulators, insulin pumps, etc.
- Metal splinters in the eye
- Metal fragments in the body near organs, vessels, or nerves
- Dental prosthesis with magnetic attachment (these are usually non-magnetic and therefore not a problem)
- Bypass vessels with magnetic holders (these are usually non-magnetic and therefore not a problem)
Please discuss the above contraindications with your doctor and bring the relevant documentation with you to the examination appointment. Ideally, you should also discuss these points with us before the examination appointment so that you do not have to come to our practice unnecessarily on the day of the examination.
If you are undergoing a heart examination (cardiac MRI), you should not drink coffee on the day of the examination. Potency-enhancing drugs (e.g., Viagra) must be discontinued at least 24 hours before a cardiac MRI!
When performing a breast examination (breast MRI), the examination should only be carried out between the 6th and 12th day after the first day of your period. In the second half of the cycle, the mammary gland tissue changes due to the increasing influence of progesterone. As a result, healthy glandular tissue also absorbs contrast medium and can no longer be reliably distinguished from diseased tissue.
It may be necessary to consult the surgeon in the following cases, among others:
- cochlear implants
- Aneurysm clips in the head The examination may be problematic in the following cases:
- Large tattoos containing colors with metal particles that can heat up during MRI scans.
- Pregnancy in the first trimester. Although no harmful effects of MRI on the fetus have been proven to date, examinations should only be performed in exceptional cases and for important reasons. The administration of contrast agents is avoided during pregnancy, except in life-threatening situations and when absolutely necessary.
- Patients who suffer from claustrophobia (fear of enclosed spaces). As a rule, however, this can be treated with medication (please bring sedatives with you) to make the examination possible. Afterwards, however, you will not be able to drive a motor vehicle or actively participate in road traffic. You must therefore be accompanied to the examination.
- When using an intrauterine device (IUD, "coil") with metal components, displacement has been described in the literature, potentially leading to insufficient contraceptive effectiveness. If in doubt, you should consult your gynecologist before and after an MRI examination to check that the device is in the correct position.
The following are not considered obstacles:
- joint prostheses
- Vascular stents
- artificial heart valves
- Wire cerclage (e.g., after heart surgery)
If there are contraindications to MRI, computed tomography, X-ray examination, or sonography may be used as alternatives.