Quantification of abdominal aortic aneurysm stiffness using magnetic resonance elastography and its comparison to aneurysm diameter

Abstract

<div class="section"> <a class="named-anchor" id="S1"> <!-- named anchor --> </a> <h5 class="section-title" id="d5040207e210">Objective</h5> <p id="P1">Abdominal aortic aneurysm (AAA) wall stiffness has been suggested to be an important factor in the overall rupture risk assessment compared to anatomical measure; we hypothesize that AAA diameter will have no correlation to AAA wall stiffness. The aim of this study is to 1) determine MRE-derived aortic wall stiffness in AAA patients and its correlation to AAA diameter; 2) determine correlation between AAA stiffness and amount of thrombus and calcium; and 3) compare the AAA stiffness measurements against age matched healthy subjects. </p> </div><div class="section"> <a class="named-anchor" id="S2"> <!-- named anchor --> </a> <h5 class="section-title" id="d5040207e215">Methods</h5> <p id="P2">In-vivo abdominal aortic MRE was performed on 36 subjects (24 patients with AAA measuring 3-10 cm and 12 healthy volunteers) aged 36-78 years old after obtaining written informed consent under the approval of the institutional review board. MRE images were processed to obtain spatial stiffness maps of the aorta. AAA diameter, amount of thrombus and calcium score were reported by experienced interventional radiologists. Spearman correlation, Wilcoxon signed rank test and Mann-Whitney test were performed to determine the correlation between AAA stiffness and diameter, and also to determine significant difference in stiffness measurements between AAA patients and healthy subjects. </p> </div><div class="section"> <a class="named-anchor" id="S3"> <!-- named anchor --> </a> <h5 class="section-title" id="d5040207e220">Results</h5> <p id="P3">No significant correlation (P&gt;.1) was found between AAA stiffness and diameter or amount of thrombus or calcium score. AAA stiffness (mean:13.97±4.2kPa) is significantly (P≤.02) higher than remote normal aorta in AAA (mean:8.87±2.2kPa) patients and in normal subjects (mean:7.1±1.9kPa). </p> </div><div class="section"> <a class="named-anchor" id="S4"> <!-- named anchor --> </a> <h5 class="section-title" id="d5040207e225">Conclusion</h5> <p id="P4">Our results suggest that AAA wall stiffness may provide additional information independent of AAA diameter, which may contribute to our understanding of AAA pathophysiology, biomechanics, and risk for rupture. </p> </div>