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Evaluation of Radiation Dose in Computed Tomography Angiography before Transcatheter Aortic Valve Implantation

Objective: To investigate the effective radiation dose and image quality of computed tomography angiography (CTA) before transcatheter aortic valve implantation (TAVI). Material and Methods: This study involved 65 participants, diagnosed with aortic valve stenosis and examined with CTA before TAVI. The total mAs, kVp, volume CT dose index (CTDIvol), and dose–length product (DLP) in each scanning phase were recorded. The effective dose was calculated by multiplying the DLP by the conversion coefficient (k=0.015 mSv/[mGy.cm]). For quantitative image analysis, circular regions of interest were placed on six levels of the aorta in the axial images. The CT attenuation value, image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured. For qualitative analysis, two radiologists rated the image quality of the aortic root and aortoiliac pathway. Results: The mean CTDIvol and DLP were 23.59±5.19 mGy and 881.01±193.41 mGy.cm., respectively. The mean effective dose was 13.22±2.90 mSv; the whole-aorta CTA phase received the highest dose, followed by the coronary CTA and coronary artery calcium scoring phases (9.62±2.60, 2.44±1.13, and 1.16±0.55 mSv, respectively). Image quality ranged from good to excellent in all segments of the aorta. Conclusion: The mean effective radiation dose of the pre-TAVI CT examination using 256-multidetector CT was 22.91± 5.03 mSv. The image quality in the aorta was good to excellent. The main factors that affected the radiation dose were: body mass index, total mAs, and kVp.