Quantification of Aortic Stiffness Using Magnetic Resonance Elastography: Measurement Reproducibility, Pulse Wave Velocity Comparison, Changes over Cardiac Cycle, and Relationship with Age

Purpose: To assess MR elastography (MRE)-derived aortic shear stiffness (mu(MRE)) measurements for: 1) reproducibility, 2) comparison to pulse wave velocity, 3) changes over the cardiac cycle, and 4) relationship with age. Methods: Cardiac-gated aortic MRE was performed on 20 healthy volunteers (aged 20-73 years). For assessing reproducibility of stiffness measurements, scans were repeated per volunteer. MRE wave images were analyzed to obtain stiffness of the abdominal aorta across the cardiac cycle, and comparisons were made with subject age. Results: Analysis of concordance correlation coefficient between scans 1 and 2 showed that r(c) = 0.86 (95% confidence interval, 0.77, 0.94) with P < 0.0001. Significantly higher mMRE was observed for all volunteers during end-systole when compared to end-diastole (P < 0.0001). mMRE increased with age; end-systolic stiffness demonstrated a relatively stronger correlation with age (r = 0.62, P = 0.003) when compared to end-diastolic stiffness (r = 0.51, P = 0.023); and the slopes of end-systole and end-diastole were found to be significantly different (P = 0.011). root mu(MRE) at end-systole and end-diastole correlated linearly with pulse wave velocity, with an r = 0.54 (P = 0.013) and r = 0.58 (P = 0.008), respectively. Conclusion: The results of this study indicate that MRE-derived aortic shear stiffness measurements are robust (reproducible and comparable to similar techniques). Mean mMRE was higher during end-systole when compared to end-diastole. mMRE was found to increase with age and showed a stronger correlation with end-systolic stiffness than with end-diastolic stiffness. (C) 2015 Wiley Periodicals, Inc.