Does altered aortic flow in marfan syndrome relate to aortic root dilatation?

Purpose: To examine possible hemodynamic alterations in adolescent to adult Marfan syndrome (MFS) patients with aortic root dilatation. Materials and Methods: Four-dimensional flow MRI was performed in 20 MFS patients and 12 age-matched normal subjects with a 3T system. The cross-sectional areas of 10 planes along the aorta were segmented for calculating the axial and circumferential wall shear stress (WSS_axial, WSS_circ), oscillatory shear index (OSI_axial, OSI_circ), and the nonroundness (NR), presenting the asymmetry of segmental WSS. Pearson's correlation analysis was performed to present the correlations between the quantified indices and the body surface area (BSA), aortic root diameter (ARD), and Z score of the ARD. P < 0.05 indicated statistical significance. Results: Patients exhibited lower WSS_axial in the aortic root and the WSS_circ in the arch (P < 0.05–0.001). MFS patients exhibited higher OSI_axial and OSI_circ in the sinotubular junction and arch, but lower OSI_circ in the descending aorta (all P < 0.05). The NR values were lower in patients (P < 0.05). The WSS_axial or WSS_circ exhibited moderate to strong correlations with BSA, ARD, or Z score (R² = 0.50–0.72) in MFS patients. Conclusion: The significant differences in the quantified indices, which were associated with BSA, ARD, or Z score, in MFS were opposite to previous reports for younger MFS patients, indicating that altered flows in MFS patients may depend on the disease progress. The possible time dependency of hemodynamic alterations in MFS patients strongly suggests that longitudinal follow-up of 4D Flow is needed to comprehend disease progress. J. Magn. Reson. Imaging 2016;44:500–508.