In vivo quantification of aortic stiffness using MR elastography in hypertensive porcine model

PurposeAortic stiffness plays an important role in evaluating and predicting the progression of systemic arterial hypertension (SAH). The aim of this study is to determine the stiffness of aortic wall using MR elastography (MRE) in a hypertensive porcine model and compare it against invasive aortic pressure measurements. MethodsRenal wrapping surgery was performed on eight pigs to induce SAH. Aortic MRE was performed at baseline and 2 months postsurgery using a retrospectively pulse-gated gradient-echo MRE sequence on a 1.5 tesla scanner. Mechanical waves of 70Hz were introduced into the aorta. Invasive central aortic pressure measurements were obtained prior to each scan to calculate mean arterial pressure (MAP). MRE data were analyzed to obtain effective aortic stiffness. Spearman's rank correlation analysis was performed to assess the relationship between MAP and MRE-derived aortic stiffness. ResultsSignificant increase in effective aortic stiffness was observed between baseline and 2 months postsurgery measurements (paired t test; P=0.004). The average MAP, determined by pooling all animals, was 65.249.42mm Hg at baseline and 92.57 +/- 11.80mm Hg 2 months postsurgery with P<0.0001. Moderate linear correlation was observed between MAP and effective aortic stiffness (=0.52; P=0.046). ConclusionThis study demonstrated that, in a SAH porcine model, MRE-derived aortic stiffness increased with increase in MAP. Magn Reson Med 78:2315-2321, 2017. (c) 2017 International Society for Magnetic Resonance in Medicine.