High-strength deep learning image reconstruction in coronary CT angiography at 70-kVp tube voltage significantly improves image quality and reduces both radiation and contrast doses

Objectives To explore the use of 70-kVp tube voltage combined with high-strength deep learning image reconstruction (DLIR-H) in reducing radiation and contrast doses in coronary CT angiography (CCTA) in patients with body mass index (BMI) < 26 kg/m(2), in comparison with the conventional scan protocol using 120 kVp and adaptive statistical iterative reconstruction (ASIR-V). Methods A total of 100 patients referred to CCTA were prospectively enrolled and randomly divided into two groups: low-dose group (n = 50) with 70 kVp, Smart mA for noise index (NI) of 36HU, contrast dose rate of 16mgI/kg/s, and DLIR-H, and conventional group (n = 50) with 120 kV, Smart mA for NI of 25HU, contrast dose rate of 32mgI/kg/s, and 60%ASIR-V. Radiation and contrast dose, subjective image quality score, and objective image quality measurement (image noise, contrast-noise-ratio (CNR), and signal-noise-ratio (SNR) for vessel) were compared between the two groups. Results Low-dose group used significantly reduced contrast dose (23.82 +/- 3.69 mL, 50.6% reduction) and radiation dose (0.75 +/- 0.14 mSv, 54.5% reduction) compared to the conventional group (48.23 +/- 6.38 mL and 1.65 +/- 0.66 mSv, respectively) (all p < 0.001). Both groups had similar enhancement in vessels. However, the low-dose group had lower background noise (23.57 +/- 4.74 HU vs. 35.04 +/- 8.41 HU), higher CNR in RCA (48.63 +/- 10.76 vs. 29.32 +/- 5.52), LAD (47.33 +/- 10.20 vs. 29.27 +/- 5.12), and LCX (46.74 +/- 9.76 vs. 28.58 +/- 5.12) (all p < 0.001) compared to the conventional group. Conclusions The use of 70-kVp tube voltage combined with DLIR-H for CCTA in normal size patients significantly reduces radiation dose and contrast dose while further improving image quality compared with the conventional 120-kVp tube voltage with 60%ASIR-V.