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


METHODS
Renal 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 70 Hz 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.


RESULTS
Significant 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 65.24 ± 9.42 mm Hg at baseline and 92.57 ± 11.80 mm Hg 2 months postsurgery with P < 0.0001. Moderate linear correlation was observed between MAP and effective aortic stiffness (ρ = 0.52; P = 0.046).


CONCLUSIONS
This study demonstrated that, in a SAH porcine model, MRE-derived aortic stiffness increased with increase in MAP. Magn Reson Med 78:2315-2321, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.|Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.
Huiming
H
Dong
Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.|Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio, USA.|Department of Biomedical Engineering, Widener University, Chester, Pennsylvania, USA.
Ria
R
Mazumder
Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.|Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.
Venkata Sita Priyanka
VSP
Illapani
Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, USA.
Xiaokui
X
Mo
Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.|Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.
Richard D
RD
White
Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.|Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.|Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.
Arunark
A
Kolipaka
D000818:Animals; D001011:Aorta / Q000000981:diagnostic imaging*; D001012:Aorta, Abdominal; D062186:Arterial Pressure; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques; D006973:Hypertension / Q000000981:diagnostic imaging*; D007090:Image Interpretation, Computer-Assisted; D007091:Image Processing, Computer-Assisted; D007668:Kidney / Q000601:surgery; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D015203:Reproducibility of Results; D013314:Stress, Mechanical; D013552:Swine; D059289:Vascular Stiffness
MR elastography; aortic stiffness; central aortic pressure; mean arterial pressure; systemic arterial hypertension