Abstract 18304: Assessment of Age-Related Aortic Stiffness With Magnetic Resonance Imaging
Background: Several methods have emerged to assess aortic stiffness with magnetic resonance imaging (MRI). We aimed to compare 3 MRI methods to assess thoracic aortic stiffness as an index of arterial aging.[[Unable to Display Character:
Methods: We studied 97 patients referred for a clinically-indicated cardiac MRI at 1.5 T. We assessed aortic stiffness via the following
Methods: (1) Pulse wave velocity (PWV) measurements from the foot-to-foot transit-time (PWV-TT) of flow between the ascending and distal thoracic descending aorta, measured via in-plane MRI phase-contrast imaging; (2) PWV estimations via the flow-area method (PWV-QA), where local PWV is computed as the ratio between ascending aortic pulsate flow (assessed with through-plane phase-contrast imaging) and change in cross-sectional area (assessed with steady-state free precession cine imaging) during the reflection-free period of the cardiac cycle (early systole); (3) Ascending aortic distensibility, measured as the fractional aortic lumen area change (assessed with steady-state free precession imaging) divided by central pulse pressure (measured with carotid applanation tonometry).[[Unable to Display Character:
Results: Semi-automated segmentation of aortic steady-state free precession cine images using active contour methods was feasible in 72.2% of cases, whereas transit-time estimations were feasible in all cases studied. Among cases with complete data,[[Unable to Display Character:
]]coefficients of correlation (R) with age were as follows: 0.49 for PWV-TT, 0.43 for PWV-QA and 0.62 for aortic distensibility (all P<0.0001). However, after adjustment for distending pressure (mean arterial pressure), partial coefficients of correlation (R) with age were as follows: 0.39 for PWV-TT (P=0.001), 0.61 for PWV-QA (P<0.0001) and 0.56 for aortic distensibility (P<0.0001).
Conclusion: Local ascending aortic distensibility or PWV assessments using the area-flow method appear to be more robust indicators of age-related large artery stiffening than the transit-time method based on in-plane phase-contrast aortic imaging. However, semi-automated aortic segmentation is not feasible in a significant proportion of cases, underscoring the need to develop more robust MRI methods to quantify aortic distension.
- © 2013 by American Heart Association, Inc.