Diagnostic procedure based on the nuclear magnetic resonance of atoms, which is used in medicine primarily for imaging organ/enorgans and tissues. With very strong magnetic fields (mostly) hydrogen nuclei are excited and their resonance is measured.
Compared to computer tomography, MRI is less invasive because it works without X-rays. However, the resolution is lower and the MRT is mainly used for soft tissue imaging.
https://de.wikipedia.org/wiki/Magnetresonanztomographie (Wikipedia CC-by-sa-3.0)