The Bland and Altman plot ratios method comparison will be utilized and the graphs displaying a scatter diagram of the ratios plotted against the averages of the SNR of ascending aorta (SNR-AA) obtained with the two different acquisitions (comparing image quality) will be generated. A generalized propensity score (to adjust for pre-operative clinical and non-clinical factors) approach accounting for the matching will be used to account for possible confounding of the association between low and traditional dose groups and annulus area, annulus perimeter, and maximum and minimum annulus diameter measurements. Moreover, adjusted (by the propensity score) Kappa tests, specificity, and sensitivity will be used to assess agreement between low and traditional dose groups. The outcomes are: CT guided successful TAVR deployment; unsuccessful TAVR deployment (moderate-severe paravalvular leak, rupture, valve embolization, mortality); acute renal failure will be defined as a reduction (pre vs post procedure) in renal function as defined by the RIFLE criteria, occurring will be used to assess differences between the study groups.