However, MRI (magnetic resonance imaging) is the preferable term; the process has nothing to do with nuclear reactions or nuclear energy or nuclear material or nuclear bombs. The fact that the thing that is resonating with EM radiation are nucleic magnetic moments does not make the process nuclear in the usual sense of the word.
CT (computer tomography), on the other hand, is slightly deceptive term; it actually gives you a dose of X-rays. It should be called X-ray Computer Tomography (XRCT).
When nuclear-magnetic resonance is used in a scientific or industrial setting for analyzing the chemical content of a sample, it is properly called NMR.
[Source: organic chemistry prof pointed this out, almost 30 years ago.]