Diffusion tensor imaging

What is diffusion tensor imaging (DTI) in PTSD?

DTI is a specialised imaging technique that uses MRI technology to investigate the movement of water within tissues of interest. By applying a magnetic field, the movement (“diffusivity”) of water molecules can be visualised in vivo. The diffusion of water is influenced by the cellular structure of the surrounding tissues, and measures such as fractional anisotropy (FA) were derived as an approximate measurement for the freedom of movement. In areas of high structural coherence such as white matter, FA is highest, indicating that water is moving in relatively fixed directions. It is lower in grey matter, and close to zero in cerebrospinal fluid, indicating that water is moving freely. Consequently, changes in FA values are interpreted to be representing alterations in the structural integrity of the regional white matter. Alterations in white matter have been found in schizophrenia and bipolar disorder, and has been investigated in PTSD.

What is the evidence for changes in white matter in people with PTSD?

Moderate to high quality evidence found both region of interest and whole brain meta-analyses showed that patients with PTSD have significantly higher FA in the inferior fronto-occipital fasciculus and lower FA in the genu of the corpus callosum. Whole brain meta-analyses also identified higher FA in the left inferior temporal gyrus and lower FA in the anterior cingulum and left corticospinal tract.

August 2021

Image: ©Michael Braham – shutterstock.com

Last updated at: 3:07 am, 11th October 2021
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Fact Sheet Technical Commentary

NeuRA Libraries

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