Low-Volume Contrast CT Angiography Via Pulmonary Artery Injection for Measurement of Aortic Annulus in Patients Undergoing Transcatheter Aortic Valve Replacement.

OBJECTIVES: To investigate the feasibility and image quality of low-dose contrast computed tomography (CT) angiography with pulmonary artery (PA) protocol. BACKGROUND: Aortic stenosis is the most common valvular heart disease and transcatheter aortic valve replacement (TAVR) has evolved as an alternative method for surgical valve replacement in intermediate-risk and high-risk surgical patients. CT is essential for measurement of aortic annulus prior to TAVR. METHODS: Twenty patients underwent a low-dose contrast study with PA protocol and 20 patients underwent a traditional-dose study (traditional protocol). In PA protocol, the pigtail catheter was advanced in the main pulmonary artery under fluoroscopic guidance, with a second pigtail placed in the abdominal aorta. The pigtail catheter and sheath were secured in position and the patient was taken to the CT scan area for CT angiography of the chest (with injection from the PA catheter), abdomen, and pelvis (with injection from abdominal aortic catheter). RESULTS: The amount of contrast used was significantly lower in the PA protocol vs the traditional protocol (40 mL vs 99.50 ± 6.87 mL; P<.001) at the cost of reduced average signal (265 ± 60 HU vs 371 ± 70 HU; P<.001), but without affecting measurements of the aortic annulus. Furthermore, no statistically significant difference in serum creatinine concentration was observed before and 48 hours after contrast administration in the PA group. CONCLUSION: Our data provide evidence that the new PA technique can be performed safely with much lower volume of CT contrast without affecting assessment of aortic annulus size.