Validation of Patient-Specific Cerebral Blood Flow Simulation Using Transcranial Doppler Measurements

Abstract

We present a validation study comparing results from a patient-specific lattice-Boltzmann simulation to transcranial Doppler (TCD) velocity measurements in four different planes of the middle cerebral artery (MCA). As part of the study, we compared simulations using a Newtonian and a Carreau-Yasuda rheology model. We also investigated the viability of using downscaled velocities to reduce the required resolution. Simulations with unscaled velocities predict the maximum flow velocity with an error of less than 9%, independent of the rheology model chosen. The accuracy of the simulation predictions worsens considerably when simulations are run at reduced velocity, as is for example the case when inflow velocities from healthy individuals are used on a vascular model of a stroke patient. Our results demonstrate the importance of using directly measured and patient-specific inflow velocities when simulating blood flow in MCAs. We conclude that localized TCD measurements together with predictive simulations can be used to obtain flow estimates with high fidelity over a larger region, and reduce the need for more invasive flow measurement procedures.

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“…We use a 3D lattice-Boltzmann solver, HemeLB [27], to simulate the continuum dynamics of bloodflow through large and highly sparse vascular systems efficiently [28]. A recent validation study focused on HemeLB simulations of a real patient Middle Cerebral Artery (MCA), using transcranial Doppler measurements of the blood velocity profile for comparison, as well as exploring the effects of a change in rheology model or inlet flow rate on the results [29]. We are now running full 3D simulations of the entire human arterial tree, with an aim of also integrating the venous tree and a cyclic coupling to state-of-the-art heart models.…”

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“…HemeLB (Hemodynamic lattice-Boltzmann) is a massively parallel LBM fluid solver developed to simulate fluid flows in sparse and complex systems on large supercomputing resources [7], [9], [10]. The aim of designing HemeLB was to provide neurosurgeons with timely and clinically relevant assistance [11]. HemeLB blood flow simulations have been deployed on High Performance Computing (HPC) platforms including HECToR, Blue Waters, SuperMUC and ARCHER [9], [10], [11].…”