This is a magnetic resonance imaging (MRI) technique that allows one to measure restricted diffusion of water through tissue. .
The main area in which diffusion tensor imaging (DTI) is used is when imaging white matter of the brain. The way in which axon bundles are oriented determines how water flows: i.e. parallel bundles of axons and their associated myelin sheaths make diffusion of H2O molecules easier along the main direction. This property can be imaged and measured with diffusion tensor imaging, and the technique is an extension of diffusion MRI.
Basically, magnetic field variations of the MRI magnet are applied in at least six different directions, which makes it possible to calculate a tensor for each voxel that shows the three dimensional shape of the diffusion pattern. With DTI white matter lesions can be found that do not show up on other MRI/imaging techniques, and can also be used to localize tumors. To do this, the brightness and mean diffusivity are measures used in a clinical setting.
Diffusion tensor imaging data can also be used to track a fiber, or path, through which information travels in our brain. As such, DTI can perform a tractography within white matter and track the path of our neural impulses from the brain, down to the spinal cord and into the peripheral nerves. Saying that this is exciting is an understatement considering the possibilities it opens up for the study of our brain. Not only can it be used to find tumors, but also to study how we process information, control our muscles and develop during childhood.
