Exploring the Biological and Mechanical Properties of Abdominal Aortic Aneurysms Using USPIO MRI and Peak Tissue Stress: A Combined Clinical and Finite Element Study

Figures

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  Fig. 1. Flowcharts detailing (a) patient inclusion/exclusion criteria and (b) the patient selection algorithm

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  Fig. 2. (a) The slice with the largest mural USPIO enhancement (most diseased segment) is selected from MRI. The corresponding slice is then extracted from the CT-based FE model using relevant anatomical landmarks (e.g. Z-distance from the iliac bifurcation). The contours are then visually compared to determine if co-location occurs. Examples of aneurysms with no co-location, some periluminal co-location (which does not represent inflammation), and true co-location of elevated stress with significant mural USPIO enhancement can be seen in panels (b), (c), and (d), respectively. Note: black arrows point to approximate regions of co-location

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  Fig. 3. Global comparisons (n = 50) of aneurysm diameter, peak stress predicted by finite element analysis, and % ∆T2* USPIO, using data from the entire aneurysm. There are no significant correlations between any of the measured parameters

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  Fig. 4. Comparisons of diameter, peak stress, and % ∆T2* USPIO uptake per group; USPIO-negative (n = 29) vs USPIO-positive (n = 21), using data from the entire aneurysm. No significant correlations demonstrated

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  Fig. 5. Mural USPIO enhancement analysis. Correlation between peak stress (derived from the entire aneurysm) with mean and peak USPIO uptake on the most diseased segment (n = 21). No significant correlations identified

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  Fig. 6. Mural USPIO enhancement analysis. Correlation between aneurysm diameter with mean and peak USPIO uptake in the identified areas of significant mural USPIO enhancement on the most diseased segment (n = 21)