Regional Mapping of Flow and Wall Characteristics of Intracranial Aneurysms

Abstract

The evolution of intracranial aneurysms (IAs) is thought to be driven by progressive wall degradation in response to abnormal hemodynamics. Previous studies focused on the relationship between global hemodynamics and wall properties. However, hemodynamics, wall structure and mechanical properties of cerebral aneurysms can be non-uniform across the aneurysm wall. Therefore, the aim of this work is to introduce a methodology for mapping local hemodynamics to local wall structure in resected aneurysm specimens. This methodology combines image-based computational fluid dynamics, tissue resection, micro-CT imaging of resected specimens mounted on 3D-printed aneurysm models, alignment to 3D vascular models, multi-photon microscopy of the wall, and regional mapping of hemodynamics and wall properties. This approach employs a new 3D virtual marking tool for surgeons to delineate the location of the resected specimen directly on the 3D model, while in the surgical suite. The case of a middle cerebral artery aneurysm is used to illustrate the application of this methodology to the assessment of the relationship between local wall shear stress and local wall properties including collagen fiber organization and wall geometry. This methodology can similarly be used to study the relationship between local intramural stresses and local wall structure.

Flow Conditions in the Intracranial Aneurysm Lumen Are Associated with Inflammation and Degenerative Changes of the Aneurysm Wall

“…Exact mathematical definitions of these quantities are given in 26 . Our choice of mesh resolution and time-step size have been shown to be adequate for accurate quantification of the spatial and time-averaged quantities considered in this work 27 .…”

Hemodynamic Characteristics of Ruptured and Unruptured Multiple Aneurysms at Mirror and Ipsilateral Locations

“…The adverse flow conditions described above have been previously shown to be associated with aneurysm wall inflammation which itself is associated with aneurysm rupture 27 , wall weakening and stiffening characteristic of vulnerable walls 28, 29 , and damaged collagen architectures 30 . Additionally, these flow conditions have been associated with aneurysm rupture 31 .…”

Combining data from multiple sources to study mechanisms of aneurysm disease: Tools and techniques

“…Samples from HUH are transported to PITT after fixation in 10% formalin. The tissue samples are then imaged with high‐resolution micro‐CT, which produces a 3D stack of images with a 3‐μm isotropic resolution using previously described techniques . Prior to imaging, small ink markings are placed on the tissue sample, which can be viewed during subsequent MPM and histological analysis.…”