摘要
目的：探讨自适应统计迭代重建（ASIR）技术对泌尿系统结石CT图像噪声和质量的影响。方法应用宝石能谱CT （Discovery CT 750 HD）对20例尿路结石患者进行CT螺旋扫描。分别采用传统滤过反投影法（FBP组）和ASIR算法对原始投影数据进行重建，后者以20％为间隔在20％～100％间重建5组图像（ASIR组）。比较不同重建图像在同一层面的图像标准差（SD值）及平均CT值，并计算信噪比和对比噪声比（CNR），采用Likert 5分制评估图像质量，通过Kappa方法评价观察者间的一致性。对FBP图像和5组ASIR图像测量结果进行方差分析，对图像噪声和ASIR取值进行相关分析。结果客观分析：①20％～100％ASIR图像的SD值小于FBP组（P＜0.05），而图像CT值差异无统计学意义；②40％～100％ASIR各组图像SNR、CNR值高于FBP组（P均＜0.05）；③图像噪声与ASIR百分比呈负相关（r=-0.529）。主观分析：①图像评定结果的观察者间一致性中等（Kappa=0.412）；②40％～100％ASIR图像评分值高于FBP组（P＜0.05）。其中60％～100％ASIR图像评分较高。结论与FBP相比，ASIR技术可降低肾结石CT噪声，有效改善图像质量；ASIR取值为60％～100％时可获得最佳图像质量。
Objective To investigate the impact of adaptive statistical iterative reconstruction（ASIR） technique on image quality and image noise of urinary calculi. Methods Twenty patients with urinary calculi underwent CT scan using Gemstone spectral CT （Discovery CT 750 HD）. The raw data were reconstructed with filtered back projection （FBP） and ASIR （20%-100% ASIR, step 20%）, respectively. The standard deviation （SD value） and average CT value were measured on the same level of different reconstructed images, then the SNR and contrast to noise ratio （CNR） were calculated. Image quality was evaluated using a 5-point scale. Kappa method was used to evaluate the consistency between the assessment results of two observers. The results of FBP and ASIR were analyzed by variance analysis,and correlation analysis was made between image noise and ASIR. Results Objective analysis： ① SD values on 20%-100% ASIR images were smaller than on FBP images （P〈0.05） without difference of CT value. In comparison with FBP, SD values reduced ASIR images,respectively. ② SNR and CNR values on 40%-100%ASIR images were larger than those on FBP images（all P〈0.05）. ③ Negative correlation was found between image noise and ASIR percentage （r=-0.529）.Subjective analysis： ① The assessment scores between two observers obtained medium consistency in subjective image evaluation （Kappa=0.412）.②There were significant differences in assessment scores between 40%-100%ASIR and FBP, while 60%-100% ASIR images had higher scores. Conclusion Compared with FBP, ASIR technique can result in noise reduction and image quality improvement of urinary calculi. Reconstruction using 60%-100% ASIR values can significantly improve image quality.
出处
《实用医技杂志》
2015年第6期581-583,共3页
Journal of Practical Medical Techniques
关键词
体层摄影术
螺旋计算机
尿路结石
噪声
图像质量
迭代重建
Tomography,spiral computed
Urinary calculi
Noise
Image quality
Herative reconstruction
