MRI hemodynamic markers of progressive bicuspid aortic valve-related aortic disease.

PURPOSE: To determine the reproducibility of MRI aortic hemodynamic markers and to assess their relationship to aortic growth in a cohort of patients with bicuspid aortic valves (BAV).
MATERIALS AND METHODS: Twenty-five patients previously studied with four-dimensional (4D) Flow imaging who had at least two separate cross-sectional imaging studies to assess for aortic growth were included: tricuspid aortic valve (TAV) controls without valvular disease (n = 12) and patients with BAV (n = 13). Flow data from the ascending aorta was used for calculation of peak velocity, normalized flow displacement, maximum wall shear stress (WSS), mean WSS, and minimal WSS. Pearson's correlation was used to evaluate interobserver agreement, and linear regression to evaluate the correlation between the different hemodynamic markers and growth. Patient informed consent was waived by the institutional review board that approved the study.
RESULTS: Peak velocity and flow displacement were very reproducible (r = 0.90-1.0 and r = 0.91-0.98, respectively). The range of WSS parameters was largely reproducible (0.47 < r < 0.96) with the greatest variability at the data extraction stage of analysis (0.47 < r < 0.85). Flow displacement best correlated with interval aortic growth (r = 0.65), peak velocity was moderately correlated (r = 0.35), but the WSS parameters did not correlate well with growth (r < 0.17).
CONCLUSION: Flow displacement is a simple and reproducible hemodynamic marker that shows good correlation with aortic growth in patients with bicuspid aortic valves.