Based on the variable absorption of x-rays by different tissues, a computed tomography(CT) imaging, also known as "CAT scanning" (Computerized Axial Tomography) is a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce a different form of imaging known as cross-sectional images (often called slices), both horizontally and vertically, of the body. The origin of the word "tomography" is from the Greek word "tomos" meaning "slice" or "section" and "graphy" meaning "drawing". A CT imaging system produces cross-sectional images or "slices" of anatomy, like the slices in a loaf of bread. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. Spatial and contrast resolution are dependent on the energy of the x-ray source, slice thickness, field of view, and scanning matrix. High resolution CT provides excellent delineation of osseous structures.

Magnetic resonance imaging (MRI) is an imaging technique used primarily in medical settings to produce high quality images of the inside of the human body. MRI is based on the principles of nuclear magnetic resonance (NMR), a spectroscopic technique used by scientists to obtain microscopic chemical and physical information about molecules. The technique was called magnetic resonance imaging rather than nuclear magnetic resonance imaging (NMRI) because of the negative connotations associated with the word nuclear in the late 1970's. MRI started out as a tomographic imaging technique, that it produced an image of the NMR signal in a thin slice through the human body. MRIs are based on totally different physical properties. An MRI is created when pulsed radio waves of a specific frequency induce the transition of a fraction of the spinning protons in the body into a higher energy state. With the termination of the radio-frequency pulse, the excited