Magnetic resonance imaging (MRI):

It is in use as a clinical diagnostic tool since 1980. The distribution of hydrogen nuclei (protons), present in cellular water, depends on the tissue type and whether or not the tissue is healthy or diseased. The MRI machine produces images by creating resonance (vibrations) in the water found in the body. The MRI uses radio waves and strong magnetic fields to create images. The radio signals emitted from the water in the body are captured by receptors, called a coil. The coil produces a cross sectional image of body water content found in the tissues. This tool can differentiate very minute differences in water density in the cellular or tissue level.