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 ( 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.