Feasibility of ultra-low contrast 64-slice computed tomography angiography before transcatheter aortic valve implantation: a real-world experience

Aims To investigate the feasibility, image quality, and clinical implications of an ultra-low-dose contrast injection computed tomography angiography (CTA) protocol in patients scheduled for transcatheter aortic valve implantation (TAVI). Methods and results Images obtained with 64-slice CT were retrospectively evaluated in 162 TAVI candidates with a body mass index (BMI) of <= 29 kg/m(2). A multiphasic, low iodine dose and BMI-adapted CM protocol was administered in all patients (BMI <22 kg/m(2): 40 mL; BMI 22-29 kg/m(2): 55 mL). All images were evaluated for image quality, vessel attenuation, and estimated radiation dose. The anatomy, diameters, perimeter, and area of the aortic annulus were assessed. Anatomy and diameters of peripheral vessels were also evaluated. Image quality of the aortic root and ilio-femoral vessels was diagnostic in all patients. Vascular attenuation was >200 HU at any vessel level. The mean diameters of the aortic annulus were 22 +/- 3 mm (range: 16-28 mm) x 26 +/- 3 mm (range: 20-33 mm); the mean perimeter was 77.0 +/- 7.1 mm. After CTA, a total of 137 patients (84.6%) underwent TAVI. Mean estimated radiation dose was 20.2 +/- 4.6 mSv. Conclusion With our protocol, we achieved images of the aortic annulus and aorto-iliac anatomy of sufficient quality to allow patient selection and procedural planning for TAVI, with a substantial reduction of the amount of injected CM.