diffusion tensor image of the brainAren’t these amazingly beautiful images of the brain? This is what we call a diffusion tensor image (DTI).  You’d think that the colours were added by a creative artist, but actually they are a code that tells us about the direction of fluid flow in the fibre tracts of the brain.  A DTI scan can therefore be used to map the brain’s fibre tracts.

That’s very useful with traumatic brain injuries (TBI) because the most common damage in TBI is diffuse axonal injury (DAI).  An axon is the longest process of a nerve, and when bundled together with other axons, forms a tract.  So DAI is injury to the fibre tracts of the brain, which we can visualise using diffusion tensor technology.  (I could say, “DTI shows DAI in TBI,” but I’ll control my acronymphilia.)

I recently saw a young man who had suffered a brain injury in a motor vehicle accident.  He had a puzzling neuropsychological profile and I couldn’t understand why he presented with organic amnesia.  I commissioned a DTI scan and it showed that the body of the corpus callosum had been destroyed, including pathways critical to memory functioning.  (The corpus callosum is the fibre tract that connects the two hemispheres of the brain.)  Suddenly all the pieces fell into place and I could provide a coherent explanation of his memory impairment and other symptoms.  Interestingly, a standard MRI brain scan did not identify the corpus callosum neuropathology.

DTI is now available in Johannesburg and can provide very useful information about the integrity of cerebral fibre tracts.  Of course, this assumes a suitably skilled radiologist to do the basic interpretation, and an appropriately knowledgeable neuropsychologist to connect the anatomical findings to the real world functioning of the patient’s brain.  This is not for sissies, so be careful who you use.  Of course, I might just know a neuropsychologist at Ormond Neuroscience who could help!!


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