Tracking of virtual particles from volumetric velocity measurements: applications to physiological flows

Continuous advancements in medical imaging are allowing the study of physiological flows with increasing accuracy and resolution, both in vitro and in vivo. In several biomedical settings, the transport of particles is an important aspect of the fluid dynamic problem, for example in the delivery of inhaled or injected drugs, and the fate of harmful agents through vessels and airways where such particles have often significant inertia. Here we utilize volumetric (three-dimensional, three-component) velocity fields obtained by Magnetic Resonance Velocimetry (MRV) to study the transport of inertial particles in cardiovascular and respiratory flows. We apply a well-established form of the particle equation of motion to track particles of given inertia that are virtually released in the flow which allows to calculate Lagrangian trajectories. The method is applied to a range of cases, including: blood clots from left ventricle assist device, thrombi in brain aneurysms, embolizing particles for tumor targeting, and inhaled aerosols in the bronchial tree.