New preprint out: Brain solute transport is more rapid in periarterial than perivenous spaces

Our new preprint on Brain solute transport is more rapid in periarterial than perivenous spaces, joint with Vegard Vinje and Erik N. T. P. Bakker, is now out on biorXiv!

Perivascular fluid flow, of cerebrospinal or interstitial fluid in spaces surrounding brain blood vessels, is recognized as a key component underlying brain transport and clearance. An important open question is how and to what extent differences in vessel type or geometry affect perivascular fluid flow and transport. Using computational modelling in both idealized and image-based geometries, we study and compare fluid flow and solute transport in pial (surface) periarterial and perivenous spaces. Our findings demonstrate that differences in geometry between arterial and venous pial perivascular spaces (PVSs) lead to higher net CSF flow, more rapid tracer transport and earlier arrival times of injected tracers in periarterial spaces compared to perivenous spaces. These findings can explain the experimentally observed rapid appearance of tracers around arteries, and the delayed appearance around veins without the need of a circulation through the parenchyma, but rather by direct transport along the PVSs.

We created computational geometries of spaces around arteries (A0, A1) and around veins (V0, V1) along the brain’s surface, and computed the flow along the length of these spaces driven by a pressure difference. The wider spaces around arteries allowed for higher flow velocities. Transport of medium-to-large tracer molecules in these spaces is mainly driven by convection (due to the relatively high Peclet numbers), and thus the higher flow velocities would also induce much more rapid tracer transport.