Three-dimensional assessment of ascending aortic stiffness, motion, and growth in ascending thoracic aortic aneurysm.

Aims: Aortic wall stiffening in ascending thoracic aortic aneurysm (aTAA) is common. However, the spatial and temporal relationships between stiffness, aortic size, and growth in aTAA remain unclear.

Methods and results: In this single-centre retrospective study, we utilized vascular deformation mapping to extract multi-directional aortic motion, aortic distensibility, and aortic growth in a multi-planar fashion from multi-phasic ECG-gated computed tomography angiograms. Aortic displacement and stiffness metrics were compared between patients with sporadic ascending aortic dilation (Dilated), individuals without thoracic aortic dilation, and patients with Marfan syndrome. A total of 96 patients were included. Total and axial aortic root motion was significantly decreased in the Dilated group (n = 49) compared with the Non-dilated group (n = 38) and Marfan group (n = 16). Aortic distensibility was significantly lower in the Dilated group compared with the Non-dilated group and exhibited a more diffuse pattern of stiffening compared with the Marfan group in which stiffening was localized to the root. In Dilated group, aortic distensibility was moderately and positively associated with aortic growth rate (R = 0.34, P = 0.02). The moderate-to-strong association between age and aortic stiffness in non-dilated segments was either significantly blunted or absent in dilated segments.

Conclusion: Vascular deformation mapping provides multi-level stiffness assessments of the ascending aorta using multi-phasic computed tomography angiography. Ascending aortic stiffening is a spatially heterogeneous process with stiffening tending to increase with degree of regional dilation and age, whereas lower stiffness was associated with faster growth of the mid-ascending aorta in those with sporadic aTAA.