Diffusion weighted imaging (DWI) capitalises on the random motion of water molecules in the body, and in particular the brain. Using specific magnetic sequencing early changes in the diffusion of water molecules can be captured on an image. There is a myriad of current and evolving applications of this imaging technique including:
Acute stroke: By far the widest application of this technique is in the early detection of stroke. The diffusion coefficient is reduced in areas of acute restricted diffusion thus confirming an acute infarction in the right clinical context. This revelation has a significant impact on acute patient care.
Brain inflammation and infection: The same principles apply in early detection of inflammatory conditions including the assessment of Multiple Sclerosis. In the latter condition, diffusion changes in normal appearing white matter have shown great promise in evaluating patients for early intervention and potentially better outcomes.
Brain tumours: Diffusion imaging helps to characterise different tumour types, especially benign from malignant lesions, and is also vital in the follow up of tumours treated with radiotherapy or chemotherapy, as well as those under surveillance after primary surgical resection.
Tractography (Diffusion tensor imaging -DTI): DTI as an off shoot of DWI is a means to more accurately represent the diffusion properties of tissues by measuring the direction of diffusion change, thus estimating entities like Fractional Anisotropy and Mean Diffusivity. These estimations can create maps of fibre tracks within the brain. Tractography images make it possible to analyse the relationship of lesions and masses in the brain to the important white matter tracts, and the surgeons use this information to plan safer surgery and minimise the damage to the surrounding normal tissues.
Paediatric applications: Using a combination of all above principles, diffusion imaging has proven to be extremely vital in the comprehensive assessment of paediatric conditions like suspect neurogenetic or neurometabolic conditions, hypoxic ischaemic insult in the newborn, brain infections and inflammation in children, as well as in the wider realm of paediatric neuro-oncology.