Magnetic resonance imaging (MRI) is the newest, and perhaps most versatile, medical imaging technology available. Doctors can get highly refined images of the body's interior without surgery, using MRI. By using strong magnets and pulses of radio waves to manipulate the natural magnetic properties in the body, this technique makes better images of organs and soft tissues than those of other scanning technologies. MRI is particularly useful for imaging the brain and spine, as well as the soft tissues of joints and the interior structure of bones. The entire body is visible to the technique, which poses few known health risks. 
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Diffusion Tensor Imaging is a building block of the fiber-tracking images. The images are presented as a set of slices, in some ways similar to traditional MRI. But in DTI, the information is presented in colors that represent the predominant direction of movement, or diffusion, of hydrogen atoms within water molecules.
     Though water appears move around freely, individual water molecules are constantly in motion, colliding with each other and encountering other cellular structures from time to time at high speeds. These high-speed collisions cause the water molecules to diffuse. In this case diffusion causes a drop of a dye which is placed at the center of a beaker of water to slowly spread apart in a spherical pattern. Water in tissues containing a large number of fibers such as skeletal muscle, and brain white matter diffuse fastest along the direction that the fibers are pointing in, and slowest at right angles to it. DT-MRI renders all the complex information about how water diffuses in tissues into intricate three-dimensional representational maps of the tissues. 
     Such data can, for example, be used to visualize and study the connectivity and continuity of neural pathways in the central and peripheral nervous systems.
     Diffusion Tensor Imaging (DTI) is becoming a routine magnetic resonance technique to study white matter properties and alterations of fiber integrity due to pathology.

Fiber tracking images are the result of data processing algorithms that are applied to DTI data.  Data points with comparable characteristics are linked to one another. The resulting information is presented as 3-D bands, strings, or tubes that use color to reinforce the information about direction.
       MRI Fiber Tracking (MR-FT) images are being used to evaluate patients with white matter disease such as multiple sclerosis.