This study utilized multidimensional dynamic computed tomography angiography (MD-CTA) to analyze the biomechanical characteristics of ascending thoracic aortic aneurysms (ATAA) in 30 subjects:​ 20 ATAA patients (12 with Marfan syndrome and 8 without) and 10 healthy individuals without ascending aortic disease. Aortic models were reconstructed from CTA images, and multi-phase displacement data were obtained via image registration. The inverse finite element method (iFEM) was applied to calculate wall tension, and displacement data was used to calculate wall strain, from which strain–tension curves were fitted. Based on these curves, we calculated the previously proposed mechanical parameters SSI and dSSI to assess wall mechanics. Given the considerable deformation of the ascending aorta, two additional parameters—potential energy reserve index (PERI) and strain resistance (Rs)—were used to evaluate energy storage. Mann–Whitney U tests revealed that both SSI and dSSI were significantly higher in the non-Marfan ATAA group compared to the Marfan and control groups, but showed no significant difference between the latter two groups. PERI and Rs were higher in the non-Marfan group compared to two other groups, reaching significance only between the non-Marfan and control groups, while the Marfan and control groups showed no significance. With further validation, these in vivo biomechanical markers may be used as complementary metrics for assessing patient-specific risk of aneurysm rupture.