Effect of reduced x-ray tube voltage, low iodine concentration contrast medium, and sinogram-affirmed iterative reconstruction on image quality and radiation dose at coronary CT angiography: Results of the prospective multicenter REALISE trial

Background: Both low tube voltage and sinogram-affirmed iterative reconstruction (IR) techniques hold promise to decrease radiation dose at coronary CT angiography (CCTA). The increased iodine contrast at low tube voltage allows for minimizing iodine load. Objective: To assess the effect of reduced x-ray tube voltage, low iodine concentration contrast medium and IR on image quality and radiation dose at CCTA. Methods: Two hundred thirty-one consecutive patients with suspected coronary artery disease were enrolled in this prospective, multicenter trial and randomized to 1 of 2 dual-source CCTA protocols: 120-kVp with 370 mgI/mL iopromide or iopamidol (n = 116; 44 women; 55.3 +/- 9.8 years) or 100 kVp with 270 mgI/mL iodixanol (n = 115; 48 women; 54.2 +/- 10.4 years). Reconstruction was performed with filtered back projection and IR. Attenuation, image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured and image quality scored. Size-specific dose estimates and effective doses were calculated. Results: There were no significant differences in mean arterial attenuation (406.6 +/- 76.7 vs 409.7 +/- 65.2 Hounsfield units; P = .739), image noise (18.7 +/- 3.8 vs 17.9 +/- 3.4 Hounsfield units; P = .138), signal-to-noise ratio (22.5 +/- 5.4 vs 23.7 +/- 6.1; P = .126), contrast-to-noise ratio (17.5 +/- 5.5 vs 18.3 +/- 6.1; P = .286), or image qualitY scores (4.1 +/- 0.9 vs 4.0 +/- 0.9; P > .05) between 120-kVp filtered back projection-reconstructed and 100-kVp IR-reconstructed series. Mean iodine dose was 26.5% lower (18.3 +/- 0.5 vs 24.9 +/- 0.9 g; P < .0001), mean size-specific dose estimate was 35.1% lower (17.9 +/- 6.6 vs 27.5 +/- 8.2 mGy; P < .0001), and effective dose was 34.9% lower (2.3 +/- 1.0 vs 3.5 +/- 1.1 mSv; P < .0001) with the 100 kVp compared with the 120-kVp protocol, respectively. Conclusion: Using low x-ray tube voltage and IR allows for decreasing the iodine load and effective radiation dose it CCTA while maintaining image quality. (C) 2015 Society of Cardiovascular Computed Tomography. All rights reserved.