Tang Hui, Yu Nan, Jia Yongjun, Yu Yong, Duan Haifeng, Han Dong, Ma Guangming, Ren Chenglong, He Taiping
1 College of Medical Technology, Shaanxi University of Chinese Medicine, Xianyang, China.
2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, China.
Br J Radiol. 2018 Jan;91(1081):20170521. doi: 10.1259/bjr.20170521. Epub 2017 Nov 16.
To evaluate the image quality improvement and noise reduction in routine dose, non-enhanced chest CT imaging by using a new generation adaptive statistical iterative reconstruction (ASIR-V) in comparison with ASIR algorithm.
30 patients who underwent routine dose, non-enhanced chest CT using GE Discovery CT750HU (GE Healthcare, Waukesha, WI) were included. The scan parameters included tube voltage of 120 kVp, automatic tube current modulation to obtain a noise index of 14HU, rotation speed of 0.6 s, pitch of 1.375:1 and slice thickness of 5 mm. After scanning, all scans were reconstructed with the recommended level of 40%ASIR for comparison purpose and different percentages of ASIR-V from 10% to 100% in a 10% increment. The CT attenuation values and SD of the subcutaneous fat, back muscle and descending aorta were measured at the level of tracheal carina of all reconstructed images. The signal-to-noise ratio (SNR) was calculated with SD representing image noise. The subjective image quality was independently evaluated by two experienced radiologists.
For all ASIR-V images, the objective image noise (SD) of fat, muscle and aorta decreased and SNR increased along with increasing ASIR-V percentage. The SD of 30% ASIR-V to 100% ASIR-V was significantly lower than that of 40% ASIR (p < 0.05). In terms of subjective image evaluation, all ASIR-V reconstructions had good diagnostic acceptability. However, the 50% ASIR-V to 70% ASIR-V series showed significantly superior visibility of small structures when compared with the 40% ASIR and ASIR-V of other percentages (p < 0.05), and 60% ASIR-V was the best series of all ASIR-V images, with a highest subjective image quality. The image sharpness was significantly decreased in images reconstructed by 80% ASIR-V and higher.
In routine dose, non-enhanced chest CT, ASIR-V shows greater potential in reducing image noise and artefacts and maintaining image sharpness when compared to the recommended level of 40%ASIR algorithm. Combining both the objective and subjective evaluation of images, non-enhanced chest CT images reconstructed with 60% ASIR-V have the highest image quality. Advances in knowledge: This is the first clinical study to evaluate the clinical value of ASIR-V in the same patients using the same CT scanner in the non-enhanced chest CT scans. It suggests that ASIR-V provides the better image quality and higher diagnostic confidence in comparison with ASIR algorithm.
通过使用新一代自适应统计迭代重建技术（ASIR-V）与ASIR算法相比较，评估常规剂量非增强胸部CT成像的图像质量改善和噪声降低情况。
纳入30例使用GE Discovery CT750HU（GE医疗，沃基沙，威斯康星州）进行常规剂量非增强胸部CT检查的患者。扫描参数包括管电压120 kVp、自动管电流调制以获得噪声指数14HU、旋转速度0.6秒、螺距1.375:1以及层厚5毫米。扫描后，所有扫描图像均采用推荐的40%ASIR水平进行重建用于比较，并以10%的增量重建不同百分比（10%至100%）的ASIR-V图像。在所有重建图像的气管隆突水平测量皮下脂肪、背部肌肉和降主动脉的CT衰减值及标准差。以标准差代表图像噪声计算信噪比（SNR）。由两名经验丰富的放射科医生独立评估主观图像质量。
对于所有ASIR-V图像，随着ASIR-V百分比的增加，脂肪、肌肉和主动脉的客观图像噪声（标准差）降低，SNR增加。30% ASIR-V至100% ASIR-V的标准差显著低于40% ASIR的标准差（p < 0.05）。在主观图像评估方面，所有ASIR-V重建图像均具有良好的诊断可接受性。然而，与40% ASIR和其他百分比的ASIR-V相比，50% ASIR-V至70% ASIR-V系列在小结构的可见性方面显著更优（p < 0.05），且60% ASIR-V是所有ASIR-V图像中最佳的系列，主观图像质量最高。80% ASIR-V及更高比例重建的图像清晰度显著降低。
在常规剂量非增强胸部CT中，与推荐的40%ASIR算法水平相比，ASIR-V在降低图像噪声和伪影以及保持图像清晰度方面显示出更大潜力。综合图像的客观和主观评估，60% ASIR-V重建的非增强胸部CT图像质量最高。知识进展：这是第一项在相同患者中使用同一台CT扫描仪对非增强胸部CT扫描中ASIR-V的临床价值进行评估的临床研究。结果表明，与ASIR算法相比，ASIR-V提供了更好的图像质量和更高的诊断置信度。
