According the Loyola UMC, "Diffusion tensor imaging tractography, or DTI tractography, is an MRI (magnetic resonance imaging) technique that measures the rate of water diffusion between cells to understand and create a map of the body’s internal structures; it is most commonly used to provide imaging of the brain. This advanced imaging technique, which provides much more detailed images of the brain than a conventional MRI, may also be used in the diagnosis of stroke, acute ischemia, brain tumors and multiple sclerosis, as well as pre-operative planning. 

Using MRI technology, DTI tractography is non-invasive and uses radio waves and a magnetic field to produce images of the brain, tissues and skull. MRI technology provides detailed images showing small changes in body tissue and blood flow, which makes it an extremely reliable tool for the detection of disease, injury, bleeding and swelling." 

To ready more please visit https://www.loyolamedicine.org/imaging-radiology/diffusion-tensor-imaging-dti-tractography