Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is an advanced imaging method that has become an attractive alternative to computed tomography.


The examination  is seemingly similar to computed tomography. The patient lies on a pad and enters a tunnel with the scanning apparatus. The device scans the targeted tissue for a certain time period and the obtained data are used to create an image visible on the computer screen. However, the principle of creating the image is completely different. Magnetic resonance imaging does not work with X-rays, but with a very strong magnetic field, which allows us to distinguish and display various tissues according to the amount of present hydrogen molecules. Although this is a very primitive description, I think it is fully sufficient for basic understanding.


The procedure does not require any special preparation. However, it is necessary to know that the patient has no magnetic material in the body and especially that he or she does not have a pacemaker. In addition, the examined person should not suffer from claustrophobia as in such case, the examination may become unbearable.


Magnetic resonance imaging may examine practically all tissues and organs and the indications are similar to computed tomography. However, while computed tomography is usually used to examine a whole part of the body (chest, abdomen, etc.), the MRI is rather used to investigated a particular organ (brain, heart, pancreas, spinal segment, etc.).The larger is the area we wanted to examine, the longer time the examination takes.


The patient should not have any magnetic objects in the body - pacemakers, artificial joints, etc. Modern materials do not respond to magnetic field, but older devices may be affected by the strong magnet of the MRI machine. Deaths of patients with pacemakers have been reported during MRI examination.


The procedure lasts much longer than conventional CT examination and the time frequently exceeds 30 minutes. During the time, the patient must lie in the tunnel within the device, which is very loud. This is very unpleasant for claustrophobic people. Severe form of claustrophobia is therefore a clear contraindication to MRI.


The main advantage of MRI is zero exposure to radiation and high-quality images of soft tissues that are beyond the capability of standard computed tomography.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources