Diffusion MRI (also known as DWI, DTI) non-invasively probes the microscopic structure of healthy and pathological tissues by monitoring the thermal motion of water in the body. It is most commonly applied in the brain, with high sensitivity to pathological processes. The presence of highly ordered cellular structures, principally in the white matter, also allows extraction of anatomical connection information.
Diffusion MRI is also increasingly seen as an important tool in the understanding of cell packing density in cancer. This can be used to asses changes in cellularity due to tumour cell death or proliferation.
Diffusion MRI in the brain
White matter axons are coherently aligned within fibre bundles. This alignment of tissue microstructure leads to an orientational preference for water diffusion, as cell membranes preferentially hinder diffusion perpendicular to the axis of the fibres. Diffusion MRI is highly sensitive to pathological effects that lead to cell damage, allowing a number of imaging biomarkers to be defined that characterise changes in water diffusion and tissue distruption.
Anatomical Connectivity Mapping (ACM)
White matter axons connect the various regions of the brain with one another in order to mediate medium-range and long-range information exchange. Bioxydyn have implemented the patented Anatomical Connectivity Mapping (ACM) technqiue to provide an index of the degree of connection from each part of the brain to the rest of the brain (for example, regions with strong anatomical connectivity demonstrate high ACM values). This measurement has been shown to be able to locate the effects of a range of neurological conditions on connections within the brain and to be sensitive to disease altering therapy.
Diffusion MRI in cancer
As in the brain, cellular microstrucure affects water diffusion in tumours. Effective cancer therapies lead to tumour cell death, which alters water diffusion and is non-invasively monitored using diffusion MRI. These changes are typically associated with the earliest stages of biological response to treatment and so can act as early markers of the influence of intervention.