Black Blood MRI within Intracranial Aneurysms: Can Eulerian and Lagrangian Characteristics of the Flow Elucidate Signal Intensity?

Previous studies have shown that the signal intensity (SI) of black blood magnetic resonance imaging (BBMRI) in the lumen of intracranial aneurysms is influenced by fluid velocity. However, in-depth analysis of hemodynamic characteristics (WSS, etc.) in direct comparison to BBMRI SI has not been performed. To determine what further fluid mechanics variables can be linked to BBMRI SI, we employ computational fluid dynamics (CFD) simulations of 3 patient-specific aneurysms at a low and high pulsatile inlet flowrate, thereby providing a large range of hemodynamic and morphological parameters, for comparison to the in-vitro MRI experiments. Vorticity, circulation, and residence time are tracked in a Lagrangian-perspective. Point-to-point comparison of BBMRI SI and the computed hemodynamics show no correlation. However, when breaking down the signal into regions based on intensity, a correlation between both vorticity magnitude and vortex circulation is found. The analysis, thus, shows that BBMRI SI does relate to multiple Eulerian parameters.