自适应性统计迭代重建在颈动脉CTA中的应用研究

夏伟委　薛蕴菁　刘元芬　江少凡　段青

[摘要] 目的 探讨自适应统计迭代重建算法在颈动脉CTA的可行性，比较权重50% ASIR重建算法相对于常规滤波反投影重建算法对图像质量的影响。 方法 随机选取64例受检者在能谱CT上行颈动脉CTA检查。采用管电压120kVp，管电流480mA，320mgI/mL碘佛醇5mL/s团注。将所得原始数据传输至GE AW4.5工作站，行影像重建分析。每组原始数据运用两类重建方法重建，分别获得对应两组数据，A组采用常规FBP重建算法对原始数据重建分析；B组运用权重50% ASIR重建算法对原始数据进行影像重建分析。分别记录两组影像颈部血管各分支CT值，噪声值及背景CT值，计算和比较图像对比噪声比（CNR），信噪比（SNR），行统计学分析。 结果 B组血管噪声值（11.5±2.38）低于A组（16.70±2.98）（P<0.01）；B组CNR（61.14±22.38）高于A组（38.19±11.57）（P<0.01）；B组SNR（48.16±18.26）也高于A组（30.03±9.49）（P<0.01）。两组血管CT值和背景CT值均无统计学意义。 结论 颈动脉CTA结合权重50% ASIR重建算法不仅可以很好保证影像质量，还能有效降低影像噪声，提高影像信噪比和对比噪声比。

[关键词] 体层摄影术；X线计算机；颈动脉CTA；自适应性统计迭代重建；信噪比

[中图分类号] R816.1 [文献标识码] B [文章编号] 2095-0616（2016）09-151-04

[Abstract] Objective To explore and discuss the feasibility of adaptive statistical iterative reconstruction algorithm in the carotid artery CTA.To compare the image quality effectS between weight 50% ASIR reconstruction algorithm and conventional filter back projection reconstruction algorithm. Methods 64 patients were randomly selected for carotid artery CTA examination in the CT spectrum，which utilized 120kVp tube voltage，480mA tube current and 320mgI/mL ioversol in 5mL/s bolus injection.The original data were transferred to the GE AW4.5 workstation for image reconstruction analysis. The original data of each group utilized two reconstruction algorithms to obtain two sets of data correspondingly.The group A adopted routine FBP reconstruction algorithm for reconstruction analysis of the original data，while the group B utilized weight 50% ASIR reconstruction algorithm for image reconstruction analysis of the original data.The CT value of image neck vessels branches，noise value and background CT value of the two groups were recorded respectively，the image contrast noise ratio （CNR） and signal to noise ratio （SNR） were calculated and compared，which had statistical analysis. Results The vascular noise value of the group B was （11.5±2.38），which was lower than the （16.70±2.98） of the group A （P<0.01）.The CNR of the group B was （61.14±22.38），which was higher than the （38.19±11.57） of the group A （P<0.01）.The SNR of the group B was （48.16±18.26），which was also higher than the （30.03±9.49） of the group A （P<0.01）.There were no statistical differences between two groups vascular CT value and background CT value. Conclusion The carotid artery CTA combined weight 50% ASIR reconstruction algorithm could not only ensure the image quality，but also effectively reduce the image noise and improve the image signal to noise ratio and contrast to noise ratio.

[Key words] Tomography；X-ray computer；Carotid artery CTA；Adaptive statistical iterative reconstruction；Signal-to-noise ratio

随着物质水平的提高和精神压力的增加，心脑血管疾病已成为常见病，多发病，越来越为人类所关注[1-2]。CT技术迅猛发展，颈动脉CTA也以其强大优势获得广泛认可。为获得较好影像质量，颈动脉CTA往往需要较大的辐射剂量[3]。因此，在降低辐射剂量的同时，如何保证图像质量，这是放射医学工作者一直关注的问题[4-5]。常规降低辐射剂量的方法有降低管电流，管电压，这些处理方式往往伴随影像噪声的提高。较少有运用影像重建技术降低辐射剂量的报道。随着能谱CT的应用和普及，自适应性统计迭代重建算法（adaptive statistical iterative reconstruction，ASiR）逐渐被人们认识。通过同组原始数据运用两种不同影像学方法重建分析，进而探讨权重50%ASIR重建相对于常规FBP重建算法的优势是此次研究的目的。……