MRT, as well as X-ray computed tomography, is a noninvasive technique of in vivo diagnostics. However, unlike X-ray tomography, MRT does not use high energy radiation. The method is based on measuring the response of hydrogen atom nuclei in an external magnetic field to the excitation of electromagnetic waves. The signals measured from the tissue depend on the local environment of hydrogen atoms and the saturation of tissue with such atoms (which is mainly defined by water distribution). Tissue differences in those parameters underlie visualisation.

There are several applications of nanotechnology for MRT development. One of them is a lymph node metastasis diagnostic based on the use of paramagnetic metal nanoparticles. Such particles accumulate in lymph nodes. MRT detection of nanoparticles makes it possible to visualise changes in the lymph node structure caused by a growing tumour.