Peeking Inside the Human Body
Magnetic Resonance Imaging (MRI) is used by doctors to create more detailed images of the human body than are possible with X-rays.
Body tissues vary in their concentration of hydrogen atoms. Fat has a high concentration, as do tissues containing water, because of the hydrogen in H2O. The concentration of hydrogen atoms in bone is very low. MRI reveals these differences in great detail, with fat and fluids (including blood) showing up as bright areas and bone as dark areas. MRI scans can even depict the brain. It produces images of such detail that they are used by researchers studying how the brain works, as well as by doctors investigating diseases.