Aortic flow patterns in patients with Marfan syndrome assessed by flow-sensitive four-dimensional MRI

To apply time-resolved three-dimensional (3D) phase contrast MRI with three-directional velocity encoding (flow-sensitive 4D MRI) for the characterization of flow pattern changes in patients with Marfan syndrome (MFS) compared with normal controls.

Flow-sensitive 4D MRI of the thoracic aorta (temporal resolution ∼45 ms, spatial resolution ∼2.4 × 2.1 × 2.8 mm(3) ) was performed in 24 MFS patients and 10 volunteers. Aortic flow patterns were visualized by 3D particle traces and streamlines. Global (affecting the complete lumen) and local (parts of the vessel lumen) helix and vortex flow in the ascending aorta (AAo), aortic arch, and descending aorta (DAo) were graded in 3 categories (blinded reading, two observers): none = 0, moderate = 1, pronounced = 2.

Flow grading revealed similar global helix and vortex flow in the AAo and arch for MFS patients and controls. Local helix flow in the AAo was significantly (P = 0.011) increased in patients and was associated with aortic sinus dilatation. The incidence of global helix and vortex flow in the DAo was increased in patients (77% and 50% of subjects) compared with controls (none and 10%).

The 4D flow analysis revealed marked differences of the aortic flow patterns between Marfan patients and controls: Local helix flow in the patients' AAo may be associated with the increased incidence of aortic root dilatation. The flow alterations in the proximal DAo could explain the occurrence of Type-B dissection originating from this site.