Is it Safe to Get an MRI?

To clarify the the "nuclear" part, magnetic resonance technology does not in any way involve nuclear reactions or the ensuing radiation from such, so you can rest easy on that one.

Additionally, MRI also doesn't utilize any ionizing radiation in the scanning process. This is one of the major advantages of imaging via MRI technology as opposed to using x-rays in traditional radiography or newer CT technologies.

What happens in NMR is that certain atomic nuclei like to align themselves with the magnetic field that they happen to find themselves in, much in the same way that you might see iron filings on a piece of paper aligning themselves with the magnetic field lines created by a toy magnet. This is where we get the M, or magnetic, part of MRI.

When these aligned nuclei are then exposed to radio waves, they will absorb and slightly later, re-emit the signal at specific resonance frequencies. This is where the R in MRI comes from. Now the trick is that the exact frequency where this happens depends on how the electrons surrounding that nucleus are arranged (which is mainly a function of what other atoms might be bonded to the one yu're looking at).

The timing and frequency at which this radio re-emission occurs allows chemists and radiologists to determine various bits of information about the different environments that these particular atoms have found themselves in, making it a very useful tool for determining chemical properties or non-invasively taking pictures of the interior of people's bodies.

Around very high-field magnets (particularly the superconducting types used in research NMR spectrometers and high-resolution closed tube MRI scanners), however, you do need to be careful about the magnets--and what ferromagnetic objects you may be bringing near or into them and how the field may affect them.

I trust most MRI techs and spectroscopists understand the proper safety procedures around their machines well enough to not allow themselves or their patients to create hazardous situations involving the magnets. These are some delicate and very expensive machines. That being said, failures can be quite spectacular--imagine Magneto and Iceman having a battle royale in your lab.

I think this is quite enough for one post, I'll leave the medical risks involving contrast dyes and incidentalomas to those more knowledgeable than myself.

This is not something to do for fun.