What is MRI and how does it work?

Please have a look at the dedicated information page on this topic.

What has to be considered regarding an MRI scan?

The general rule is: No ferromagnetic materials should be taken into the scanner or even the vicinity. The magnetic field of an MR scanner is so strong that even heavy ferrous objects will be pulled towards it, which can be quite dangerous. Any sort of card with a magnetic strip should not come close to the magnet since they could get deleted. Also phones, watches or hearing aids can take irreparable damage. But don't be scared: Before you get anywhere near an MR scanner, you will be informed about possible dangers and asked to take off any potentially harmful objects or clothes, like watches, belts and also piercings. As a volunteer, you will be provided safe clothing, thus it won't be possible to forget something critical on your body.

Under which conditions is one not allowed to receive an MRI scan?

Implants or other materials in the volunteer's body could be influenced by the magnetic and radio-frequency fields in the MRI scanner which could lead to impairment of functionality and severe injuries. Therefore, people with any sort of implants or unnatural material in their bodies will be checked in-depth whether they can safely take part in such an examination. Since we care for your safety, we will personally inform you and provide a questionnaire upfront, to make sure that you are allowed to participate in an MRI scan.

In addition, one has to consider that an examination in an MR scanner may take a long time. To obtain images with best quality, the volunteer must stay calm and should not move throughout the entire examination. If this is not possible, e.g. because of pain or other restrictions, one should reconsider to participate in an MR scan. Additionally, for people with claustrophobia it can be very difficult to lie inside an MR scanner.

What is contrast agent?

Contrast agents contain certain paramagnetic substances that locally interact with the magnetic field which in return influences the received MR signal. There is no radiation involved and it is safe. Under normal conditions the human body already contains such substances (e.g. decomposition products from haemoglobin). In MRI usually gadolinium is used, which is a ductile rare-earth metal. Contrast agents help to distinguish pathological tissue from normal tissue.

Why is MRI so loud?

An MR scan can reach the volume of a starting jumbo jet during a measurement. These loud knocking sounds are generated by the so-called gradient coils which are used to encode the origin of the received MR signals to subsequently form an image. However, the necessary electrical currents that flow through the gradient coils are switched very quickly. The resulting (quickly changing) magnetic fields interact with the main magnetic field which cause the coils vibrate. To be protected from this noise, the volunteers are provided with earplugs before each measurement.

How long does an MRI scan take?

The duration of a MR examination depends on the examined body part, the particular interest of the study and the desired image quality. For regular examinations the estimated amount of time is 25-40 minutes. However, the individual scan duration can be significantly shorter or longer, depending on the study layout. If you are interested in signing up as a study subject, however, you will be supplied with all necessary information beforehand.