ABSTRACT
An imaging technique is one that allows the visualization of structural features of the nervous system or pharmacological processes resulting from the use of specially treated chemical substances. The urge to know what happens inside the brain when one thinks has captured the interest of many since the brain was first conceived as the site of thinking. Injecting opaque substances into the vascular system of cadavers, the visualization of blood vessels by X-ray gave rise to angiography. However, it was not until 1926 that Egas-Moniz, a Portugese neurosurgeon, performed an angiogram in a live patient for the first time. Pneumoencephalography involves the injection of air into the cavities of the nervous system for imaging purposes. The imaging principle of Magnetic resonance imaging (MRI) scanning is based on the magnetic properties of element nuclei containing an odd number of protons. MRI scanners generate a density map of hydrogen, contained in water, makes up 75% of the composition of the human body.
