3.2.3. Magnetic Resonance Imaging (1980’s). This technique relies on the relaxation
properties of magnetically-excited hydrogen nuclei of water molecules in the
body. The patient under study is briefly exposed to a burst of radio-frequency
energy, which, in the presence of a magnetic field, puts the nuclei in an elevated
energy state. As the molecules undergo their normal, microscopic tumbling, they
shed this energy into their surroundings, in a process referred to as relaxation. Images
are created from the difference in relaxation rates in different tissues. This
technique was initially known as nuclear magnetic resonance (NMR) but the term
“nuclear” was removed to avoid any association with nuclear radiation