In Vitro Study of Particle Transport in Successively Bifurcating Vessels
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Annals of Biomedical Engineering ( 2019) https://doi.org/10.1007/s10439-019-02293-2
In Vitro Study of Particle Transport in Successively Bifurcating Vessels OMID AMILI ,1 JAFAR GOLZARIAN,2 and FILIPPO COLETTI1,3 1
Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, MN, USA; 2Department of Radiology, University of Minnesota, Minneapolis, MN, USA; and 3St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN, USA (Received 7 February 2019; accepted 20 May 2019) Associate Editor Umberto Morbiducci oversaw the review of this article.
Abstract—To reach a predictive understanding of how particles travel through bifurcating vessels is of paramount importance in many biomedical settings, including embolization, thromboembolism, and drug delivery. Here we utilize an in vitro model in which solid particles are injected through a rigid vessel that symmetrically bifurcates in successive branching generations. The geometric proportion and fluid dynamics parameters are relevant to the liver embolization. The volumetric flow field is reconstructed via phase-contrast magnetic resonance imaging, from which the particle trajectories are calculated for a range of size and density using the particle equation of motion. The method is validated by directly tracking the injected particles via optical imaging. The results indicate that, opposite to the common assumption, the particles distribution is fundamentally different from the volumetric flow partition. In fact, the amount of delivered particles vary substantially between adjacent branches even when the flow is uniformly distributed. This is not due to the inertia of the particles, nor to gravity. The particle distribution is rather rooted in their different pathways, which in turn are linked to their release origin along the main vessel cross-section. Therefore, the tree geometry and the associated flow streamlines are the prime determinant of the particle fate, while local changes of volumetric flow rate to selected branches do not generally produce proportional changes of particle delivery. Keywords—Particle embolization, Bifurcating PC-MRI, Lagrangian particle tracking.
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INTRODUCTION Biological fluids characteristically flow through successive generations of bifurcating branches in highly ramified systems. The velocity pattern at and past the branching points can already be fairly complex, especially if inertial effects are at play. When the Address correspondence to Filippo Coletti, St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN, USA. Electronic mail: [email protected]
fluid carries discrete solid particles, predicting their transport becomes a very challenging problem. Specifically, we ask: how do particles, initially traveling in a parent vessel, distribute among the distal branches a number of generations downstream? This question is highly relevant to a wide array of physiological and biomedical settings. Examples include: the transport of cardiogenic thrombi42; the inhalation of airborne particulat
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