Atlas-Based Evaluation of Hemodynamic in Ascending Thoracic Aortic Aneurysms

Abstract

Atlas-based analyses of patients with cardiovascular diseases have recently been explored to understand the mechanistic link between shape and pathophysiology. The construction of probabilistic atlases is based on statistical shape modeling (SSM) to assess key anatomic features for a given patient population. Such an approach is relevant to study the complex nature of the ascending thoracic aortic aneurysm (ATAA) as characterized by different patterns of aortic shapes and valve phenotypes. This study was carried out to develop an SSM of the dilated aorta with both bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV), and then assess the computational hemodynamic of virtual models obtained by the deformation of the mean template for specific shape boundaries (i.e., ±1.5 standard deviation, σ). Simulations demonstrated remarkable changes in the velocity streamlines, blood pressure, and fluid shear stress with the principal shape modes such as the aortic size (Mode 1), vessel tortuosity (Mode 2), and aortic valve morphologies (Mode 3). The atlas-based disease assessment can represent a powerful tool to reveal important insights on ATAA-derived hemodynamic, especially for aneurysms which are considered to have borderline anatomies, and thus challenging decision-making. The utilization of SSMs for creating probabilistic patient cohorts can facilitate the understanding of the heterogenous nature of the dilated ascending aorta.

The Use of Digital Coronary Phantoms for the Validation of Arterial Geometry Reconstruction and Computation of Virtual FFR

“…As we state from the outset, the objective of our DP is to create geometries that are mathematically defined and realistic, but computationally tractable with the minimum number of parameters that would allow reasonable customisation, without adding unnecessary complexity that would hinder the identifiability of error sources and modes of error propagation. However, their use is a possible research direction for our work, following the workflow of Catalano et al in [27], for example. In the above, a statistical shape model of the aortic arch is constructed from a library of n = 106 patients, an average "template" shape is identified, and principal component analysis is performed to identify modes of variation of the geometry across the population.…”

Analysing functional implications of differences in left ventricular morphology using statistical shape modelling

“…patient grouping/categorization) we could then unpack the relationship between morphological and functional element and risk-stratify the groups. Also, future studies can take advantage of such a powerful tool as the atlas-based disease assessment to reveal haemodynamic insights 32 . Changes in myocardial thickness were beyond the scope of this study but could be included in future investigations.…”

Existing and Emerging Approaches to Risk Assessment in Patients with Ascending Thoracic Aortic Dilatation

“…The authors created the ascending thoracic aortic aneurysm template, which may be modelled to see the differences that it produces in the flow patterns, blood pressure, and fluid shear forces when they are deformed. The authors performed the exquisite atlas-based analyses to understand the mechanistic link between the shape and the pathophysiology [ 42 ].…”