diffusion tensor imaging

Syllable breakdown

Dictionary meaning

an advanced magnetic resonance imaging technique that measures the directional diffusion of water molecules through biological tissue to infer the structure and integrity of white matter tracts in the brain and spinal cord; water molecules diffuse freely in all directions (isotropically) in cerebrospinal fluid, but in the white matter of the brain they are constrained to diffuse preferentially along the axes of myelinated axon bundles rather than across them (anisotropic diffusion); by measuring the degree and direction of this directional restriction using MRI pulse sequences sensitive to molecular diffusion, DTI can map the architecture of white matter pathways — the structural connectivity of the brain — in three dimensions; fractional anisotropy (FA), mean diffusivity (MD), and tractography — the computational reconstruction of white matter tracts as streamlines — are the main outputs of DTI; DTI is used clinically to evaluate white matter diseases including multiple sclerosis, traumatic brain injury, and stroke, and in neurosurgical planning to identify critical white matter tracts adjacent to brain tumours

Examples

• Diffusion tensor imaging revealed disruption of the corticospinal tract adjacent to the glioma, guiding the neurosurgeon's resection strategy.
• DTI tractography demonstrated reduced fractional anisotropy in the corpus callosum of patients with mild traumatic brain injury.

Synonyms: DTI, diffusion tensor MRI, white matter tractography