The purpose of this study is to evaluate contrast media volume, safety and 30-day outcome of patients after a computed tomography (CT) scan. The results of this study will help to determine the minimum volume of contrast material that can be used to ensure patient safety while not compromising diagnostic image quality in high-risk patients.

The scholarly rationale for the study is to determine the feasibility of restricting the contrast media volume to 60ml of 270mg Iodine (mgI)/ml iodixanol or less to accomplish sufficient intravascular attenuation for comprehensive CT assessment prior to TAVR. The study will also evaluate the effects of contrast media administration on our subjects' kidney function by performing serum creatinine measurements at baseline, as well as at three days and thirty days after contrast media administration.

Inclusion Criteria:

1. Subject must be 18-90 years of age.
2. Subject must have been referred for a clinically indicated CT prior to TAVR.
3. Subject must provide written informed consent prior to any study-related procedures being performed.
4. Subject must be willing to comply with all clinical study procedures.

Exclusion Criteria:

1. Subject is a pregnant or nursing female. Exclude the possibility of pregnancy:

   • By testing (serum or urine βHCG) within 24 hours before contrast agent administration, or
   • By surgical sterilization, or
   • Post menopausal, with minimum one (1) year history without menses.

2. Subject has an acute psychiatric disorder or is cognitively impaired.

3. Subject is using or is dependent on substances of abuse.

4. Subject is unwilling to comply with the requirements of the protocol.

5. Subject has previously entered this study.

6. Subject has an allergy against iodinated contrast agents.

7. Subject is in acute unstable condition.