  Brain-related experiments are limited by nature, and so biological insights
are often restricted or absent. This is particularly problematic in the context
of brain cancers, which have very poor survival rates. To generate and test new
biological hypotheses, researchers started using mathematical models that can
simulate tumour evolution. However, most of these models focus on single-scale
2D cell dynamics, and cannot capture the complex multi-scale tumour invasion
patterns in 3D brains. A particular role in these invasion patterns is likely
played by the distribution of micro-fibres. To investigate explicitly the role
of brain micro-fibres in the 3D invading tumours, in this study we extend a
previously-introduced 2D multi-scale moving-boundary framework to take into
account 3D multi-scale tumour dynamics. T1 weighted and DTI scans are used as
initial conditions for our model, and to parametrise the diffusion tensor.
Numerical results show that including an anisotropic diffusion term may lead in
some cases (for specific micro-fibre distributions) to significant changes in
tumour morphology, while in other cases it has no effect. This may be caused by
the underlying brain structure and its microscopic fibre representation, which
seems to influence cancer-invasion patterns through the underlying
cell-adhesion process that overshadows the diffusion process.
