Quantification of near‐wall hemodynamic risk factors in large‐scale cerebral arterial trees

Abstract

Detailed hemodynamic analysis of blood flow in pathological segments close to aneurysm and stenosis has provided physicians with invaluable information about the local flow patterns leading to vascular disease. However, these diseases have both local and global effects on the circulation of the blood within the cerebral tree. The aim of this paper is to demonstrate the importance of extending subject-specific hemodynamic simulations to the entire cerebral arterial tree with hundreds of bifurcations and vessels, as well as evaluate hemodynamic risk factors and waveform shape characteristics throughout the cerebral arterial trees. Angioarchitecture and in vivo blood flow measurement were acquired from healthy subjects and in cases with symptomatic intracranial aneurysm and stenosis. A global map of cerebral arterial blood flow distribution revealed regions of low to high hemodynamic risk that may significantly contribute to the development of intracranial aneurysms or atherosclerosis. Comparison of pre-intervention and post-intervention of pathological cases further shows large angular phase shift (~33.8°), and an augmentation of the peak-diastolic velocity. Hemodynamic indexes of waveform analysis revealed on average a 16.35% reduction in the pulsatility index after treatment from lesion site to downstream distal vessels. The lesion regions not only affect blood flow streamlines of the proximal sites but also generate pulse wave shift and disturbed flow in downstream vessels. This network effect necessitates the use of large-scale simulation to visualize both local and global effects of pathological lesions.

Quantification of blood flow patterns in the cerebral arterial circulation of individual (human) subjects

“…An efficient optimization approach was demonstrated to determine dynamic boundary pressure waveforms when dynamic flow measurements were available. The inferred pressure waveform can be compared to 3D DFD results reported previously . Without small perforator compensation, pressure drop predictions from the carotid to the pial network reached as high as ~90mmHg, a value that is certainly too large.…”

“…The four outflow splitting methods presented here were needed for flow hemodynamic flow reconstruction in the full cerebral arterial networks. Similar closures were previously considered for 3D CFD problems and dynamic blood flow networks . Splitting assumptions were not needed in the reduced network modeling, because in vivo flow measurements at all inlet and outlet vessels in the reduced arterial networks were available.…”

Validation of parametric mesh generation for subject-specific cerebroarterial trees using modified Hausdorff distance metrics

“…Hemodynamic analysis with the elevated RRT region in the basilar artery is shown in Figure 9. Detailed hemodynamic risk factor analysis in large-scale human arterial trees is discussed elsewhere 19 .…”

Voxelized simulation of cerebral oxygen perfusion elucidates hypoxia in aged mouse cortex

“…These methods are discussed in more detail in the discussion section. Other groups performed dynamic 3D hemodynamic simulations effectively solving blood flow in the visible portion of the main cerebral arteries using parametric structured body fitted meshes [48][49][50]. The Sarntinoranont group introduced an elegant voxel-based method for predicting drug dispersion in spinal tissue; her method had the advantage that it seamlessly integrated the information flow between image data and simulations by aligning simulation results with image data at the same Cartesian "voxel" grid [51].…”