Department of Radiology, Institute of Radiation Medicine, Seoul National University Hospital, 28 Yongon-Dong, Chongno-Gu, Seoul 110-744, Korea.
Int J Cardiovasc Imaging. 2013 Mar;29(3):669-76. doi: 10.1007/s10554-012-0113-6. Epub 2012 Aug 26.
To assess the image quality of coronary CT angiography (CCTA) of 640-slice CT reconstructed by Adaptive Iterative Dose Reduction (AIDR) three-dimensional (3D) in comparison with the conventional filtered back-projection (FBP). CCTA images of 51 patients were scanned at the lowest tube voltage possible on condition that the built-in automatic exposure control system could suggest the optimal tube current. They were, then, reconstructed with FBP and AIDR 3D (standard). Objective measurements including CT density, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were performed. Subjective assessment was done by two radiologists, using a 5-point scale (0:nondiagnostic-4:excellent) based on the 15-coronary segment model which was grouped into three parts as the proximal, mid, and distal segmental classes. Radiation dose was also measured. AIDR images showed lower noise than FBP images (45.0 ± 9.4 vs. 73.4 ± 14.6 HU, p < 0.001) without any significant difference in CT density (665.5 ± 131.7 vs. 668 ± 136.3 HU, p = 0.8). Both SNR (15.0 ± 2.1 vs. 9.2 ± 1.7) and CNR (16.8 ± 2.3 vs. 10.4 ± 1.8) were significantly higher for AIDR than FBP (p < 0.001). Total subjective image quality score was also significantly improved in AIDR compared with FBP (3.1 ± 0.6 vs. 1.6 ± 0.4, p < 0.001), with better interpretability of the mid and distal segmental classes (100 vs. 95 % for the mid, p < 0.001; 100 vs. 90 % for the distal, p < 0.001). Mean effective radiation dose was 2.0 ± 1.0 mSv. The AIDR 3D reconstruction algorithm reduced image noise by 39 % compared with the FBP without affecting CT density, thus improving SNR and CNR for CCTA. Its advantages in interpretability were also confirmed by subjective evaluation by experts.
为了评估 640 层 CT 自适应迭代剂量降低（AIDR）三维（3D）重建冠状动脉 CT 血管造影（CCTA）的图像质量，并与常规滤波反投影（FBP）进行比较。对 51 例患者在能建议最佳管电流的内置自动曝光控制系统条件下以最低管电压进行 CCTA 扫描。然后，使用 FBP 和 AIDR 3D（标准）进行重建。进行客观测量，包括 CT 密度、噪声、信噪比（SNR）和对比噪声比（CNR）。两位放射科医生使用基于 15 节段模型的 5 分制（0：无法诊断-4：优秀）进行主观评估，该模型分为近端、中段和远端节段组。还测量了辐射剂量。AIDR 图像的噪声低于 FBP 图像（45.0 ± 9.4 比 73.4 ± 14.6 HU，p < 0.001），而 CT 密度无明显差异（665.5 ± 131.7 比 668 ± 136.3 HU，p = 0.8）。SNR（15.0 ± 2.1 比 9.2 ± 1.7）和 CNR（16.8 ± 2.3 比 10.4 ± 1.8）均显著高于 FBP（p < 0.001）。与 FBP 相比，AIDR 的总主观图像质量评分也显著提高（3.1 ± 0.6 比 1.6 ± 0.4，p < 0.001），并且中段和远端节段的可解释性更好（中段为 100 比 95%，p < 0.001；远端为 100 比 90%，p < 0.001）。平均有效辐射剂量为 2.0 ± 1.0 mSv。与 FBP 相比，AIDR 3D 重建算法将图像噪声降低了 39%，而不影响 CT 密度，从而提高了 CCTA 的 SNR 和 CNR。专家的主观评估也证实了其在可解释性方面的优势。
