— | Albert Einstein, July 2, 1945 |

Diffusion Tensor Imaging(DTI): a magnetic resonance imaging technique that uses single-shot echo-planarMRIpulse sequences which have been optimized to detect the diffusivity ofwater moleculesin tissue. By inducingmagnetic gradientsin differentnon-colinear directionswhile a subject is in the scanner, a series ofdiffusion weighted images(DWIs) can be acquired. For each given gradient, the echo attenuation values (ie “intensities”) at each voxel can then be used to calculate theapparent diffusion coefficient(ADC). The set of ADCs for each voxel can be used in turn to calculate the diffusion tensor for that voxel, an ellipsoid which models the diffusion profile of water within that voxel. Theeccentricityof the ellipsoid is known as theFractional Anisotropy(FA); the mean of the three principleeigenvectorsis known asthe mean diffusivity(MD).Source&Credit: DTI Notes, Jesse Brown, UCLA