Diffusion MRI & Tractography DTI
Diffusion MRI (dMRI) measures the mobility of water molecules in the brain.
As water molecules tend to diffuse along, rather than across, brain white matter fibres, it is possible to map the structure and integrity of major water matter tracts in 3 dimensions, DTI (Tractography). Mapping the structure of white matter tracts, effectively the brain's wiring, in vivo allows an understanding of how different brain regions are connected and how diseases such as stroke, intracranial tumours and schizophrenia affect white matter and cause neurological problems.
The above are standard axial diffusion tensor MRI (DT-MRI) parametric maps obtained from a healthy volunteer.
(a) T2-weighted image showing brain (grey) and cerebrospinal fluid (white). (b) The magnitude of water molecule diffusion or mean diffusivity (MD). (c) A scalar measure of diffusion anisotropy (FA), i.e. the deviation from pure isotropic diffusion of water mobility in vivo. This diffusion anisotropy arises due to the presence of axonal membranes and myelin which causes water molecules to diffuse preferentially along the long axes of ordered axonal fibres rather than across them. These diffusion tensor parameters are therefore thought to provide useful biomarkers of white matter fibre tract integrity, with low values of (grey) and high values of FA (white) indicating intact healthy coherent axons. (d) Simple colour composite map showing the principal direction of water mobility (red = left/right, green = anterior/posterior, blue = superior/inferior).
The above video clip shows a three dimensional rotating colour coded map showing the white matter tracts produced from DT-MRI data acquired at BRIC, Edinburgh
If you wish further information on any of the above activities, then please contact Dr Mark Bastin: