We see something because photons bounce off a surface and enter our eyes, interacting with the rods and cones to generate the image. We perceive the object in different colors because different surfaces absorb different frequencies of light. In Magnetic Resonance Imaging (MRI), the imaging sensors perceive the nuclear magnetic resonance from certain types of atoms, specifically, those with an imbalance between neutrons and protons in their nucleus. This idea was behind nuclear magnetic resonance (NMR) spectroscopy. Still, it is one thing to detect the presence or absence of certain isotopes and another to map their positions within a living body. The living qualifier is crucial because it substantially reduces the strength of the magnetic field that can be used; NMR spectroscopy typically uses field strengths an order of magnitude greater than those used for MRI, which would cook the human flesh. MRI should be called (and was for a while) NMRI, but the word “nuclear” was dropped from the name of this modality because manufacturers thought patients might be squeamish about being put in a machine with the word “nuclear” in its name.