Back to the topic! MR is awesome!
MRI is nice, but I really really love NMR spectrography!
It's so incredibly elegant. See, organic compounds are bound together by fused/shared orbitals. These "bonds" affect the nuclear magnetic resonances, both those of the primary nucleus (the one originating the resonance) but also of the neighboring nuclei, and of their neighbors. It's a bit like one of those mobiles you can hang from the ceiling, the shared hybridized orbitals serve to transfer part of the tug on one nucleus to the next one, and from there again to the next.
What this means for spectrography is that each organic compound will give a unique spectrum, one which can be analyzed to show which substance is in question.
It's very powerful, and it can be fun too. Puzzling out which interferences are the cause of the intricate patterns appearing is better than Sudoku
