Abstract
Marfan syndrome (MFS) is a disorder of connective tissue structure caused by a mutation in the fibrillin 1 (FBN1) gene. Aortic root dilatation, aneurysms and subsequent dissection occurring in the aorta are considered to be the risk of sudden death for patients. Increased helical flow in the aorta will result in abnormal cardiac functions. The aim of this study were to visualize and quantify helical flow in aortic flow for MFS patients compared with normal subjects. Flow patterns and hemodynamic parameters in the thoracic aorta were visualized and quantified based on time-resolved 3D phase contrast MRI with three-directional velocity encoding (4D flow MRI, temporal resolution ~40 ms, spatial resolution ~1.17 mm) in 18 patients with confirmed MFS (age = 25.0 ± 7.1 years) and in 15 age-matched normal subjects (age = 29.0 ± 10.6 years). Aortic root diameter and Z score for MFS patients (38.9 ± 8.9 mm; 3.4 ± 3.1) were significant larger than that for normal subjects (25.9 ± 4.5 mm; -0.9 ± 1.2). Visualization of aortic flow were evaluated in commercial software. The grading of aortic flow and larger rotational angles in ascending aorta and aortic arch showed that MFS patients had smaller velocity and less bifurcation characteristics for blood flow propagation. The hemodynamic parameters, including velocity, helicity density, relative helicity and axial wall shear stress, had distinguished MFS patients to normal subjects mostly in ascending aorta. Spatiotemporal distribution of relative helicity clearly showed the difference of core center between MFS patients and normal subjects, which provided promising approaches for patient managements in the future.