Diffusion imaging is not limited to basic measures like FA (fractional anisotropy), or even fiber tractography; other microstructure elements can be of major interest. Free-water is a telling example.
Imeka’s diffusion imaging tools are able to measure extracellular water fraction (free-water), which in turn serves to measure neuroinflammation.
There is currently no way to measure inflammation in the brain’s white matter. Certain PET markers are in development, but they are not considered as usable options in the near future. Furthermore, PET imaging is a highly invasive and expensive way of measuring markers in the body.
Neuro-inflammation measured by free-water imaging based on MRI is a fast and cost-effective method to assess neuroinflammation, and it is available today.
Imeka’s infrastructure is already used in a clinical trial setting. For example, our team has worked on existing databases (ADNI, ADNI+, ADNI2) and significant differences between study groups were observed based on this measure.
Imeka’s expertise with free-water imaging lead to a collaboration with Pfizer, a project that became the subject of an abstract at the 2018 ISMRM conference.
On top of free-water, Imeka can measure intracellular, hindered and extra-cellular water. We assign a constant to CSF (cortico-spinal fluid), to make sure it does not affect our free-water signal.
It’s a simple, yet powerful way of assessing extra-cellular water which can be associated with inflammation.
The acquisition time necessary for us to get proper data to perform processing is quite short, in the 5-7 minutes range, for a subject in the MRI.
Legacy dataWe are also able to work with data that was acquired in the past. With a limited amount of directions of acquisition, we can extract significant information from legacy data.
Free-water imaging can also be used to remove free-water from the signal. This is particularly useful in cases of brain lesions in order to discern what’s hidden within.
The best example? Multiple Sclerosis. We have been able to “track” through lesions by removing the free-water component of the signal.
Differentiating edema from tumour
Another very important aspect of the free-water component for neurosurgeons is that we can help differentiate edema from tumor and from sane tissue in the brain.