During radiological imaging, the CT images were gated to the end-diastolic phase of the cardiac cycle; therefore, the patient-specific CT image-based models ($Sib$) correspond to a pressurized state where the intraluminal pressure is the patient-specific diastolic pressure. The algorithm starts by recording the nodal configuration [$Nk,ibS(X)$] of the initial CT image-based FEA mesh of the solid domain. In the first stage of the algorithm, uniform pressure is applied on the endoluminal surface through increments starting from 0 to the diastolic pressure in a quasi-static FE simulation. From the FEA results, the displacement of each node of the solid mesh [$Dk,ibS(X)$] is obtained. The displacement components in the three Cartesian coordinates ($Dx$, $Dy$, and $Dz$) are recorded at each node for the last three pressure increments and fitted separately to quadratic curves to form three displacement–pressure plots (i.e., $Dx\u2212p$, $Dy\u2212p$, and $Dz\u2212p$ plots). The displacement components corresponding to the unloaded configuration for each node are obtained by extrapolating the corresponding displacement–pressure plots to the zero pressure. Figure 2 shows the displacements of the last three increments for a random node in model AAA1. The displacements are extrapolated by second-order quadratic fitting (solid lines) and were found to be nonlinear. Linear extrapolation (dashed lines) is also shown for qualitative comparison with the quadratic fit. The calculated displacement components are then added to the initial spatial coordinates $Nk,ibS(X)$ to obtain the first approximation of the nodal coordinates $Nk,ugS(X)$ of the unloaded geometry ($Sug,1$). In the second step, the $Sug,1$ is subject to corrections using a fixed point iteration scheme to reconstruct the final unloaded geometry. $Sug,1$ is first subjected to the same diastolic pressure distribution and boundary conditions. Nodal displacements [$Dk,ugS(X)$] are then recorded from the FEA simulation results. According to our assumptions, the nodal configuration of the deformed unloaded geometry [$Nk,ugS(X)+Dk,ugS(X)$] should match the nodal configuration of the initial CT image-based geometry [$Nk,ibS(X)$] within a user specified tolerance. We characterized the mismatch between these two geometries by measuring the relative L^{2}-norm error of the nodal positions.