迭代重建在膝关节置换术后X线数字化断层融合检查中的应用价值

目的：探讨 X 线数字化断层融合（DTS）运用迭代重建技术（IR），降低膝关节图像金属植入物伪影的可行性和临床应用价值。方法：79例人工膝关节置换术后患者行 DTS 扫描，分别采用滤波反投影重建（FBP）技术和迭代重建（IR）技术对原始图像进行重建。从图像清晰度、假体金属植入物与周围骨相连结构的显示度、金属伪影的多少等方面对两组图像进行分析并评价。根据骨科临床对人工膝关节的分区，在后处理工作站上测量 A1～A7区域内假体与骨之间硬化束金属伪影的长度。结果：对两种重建技术所得到的图像进行主观评价，IR 组优片率为88．6％，FBP 组优片率为62％， IR 组优片率高于 FBP 组，差异有统计学意义（P ＜0．05）。IR 组重建图像在 A1、A3～A7区域无金属伪影，仅3例图像 A2区域见少许金属伪影，A7区域关节间隙内聚氨酸脂软垫显示清晰；FBP 组人工假体在 A1～A7区域均见金属伪影，伪影长度为0．5～2．6 mm。FBP 组图像伪影明显多于 IR 组。结论：有金属植入物的人工膝关节置换术后患者行 DTS 检查，运用 IR 技术可明显减少金属植入物伪影，图像质量明显改善，在术后随访中具有较高的临床应用价值。

Application of the Iterative reconstruction technique in digital tomosynthesis examination after knee joint replacement

Objective:To study the feasibility and clinical application of using iterative reconstruction technique (IR) in the digital radiographic tomosynthesis (DTS)to reduce the artifact by metallic implant in the knee-joint images.Methods:79 patients received knee joint replacement were recruited and underwent DTS scan.The original data were reconstructed by filtered back-projection and iterative reconstruction (IR)technique respectively.These two groups of images were analyzed and scored according to the distinctness of image,the visibility of the connection structure between metallic implants and the surrounding bones and metallic artifacts.The length of beam hardening artifacts between the metallic prosthesis and bones was measured in the fields of A1~A7 at the post processing workstation according to the zoning of the artificial knee joint by orthopedics clinical application.Results:The images obtained by the two reconstruction techniques were subjectively eval-uated.The satisfactory rate of IR group images was 88.6 %,which was higher than that of FBP group (62%),with signifi-cant statistic difference (P <0.05).There was no metallic artifacts in the image of IR group in the field of A1,A3~A7,on-ly few metallic artifacts in the field of A2 were showed in 3 cases.In the field of A7,images of polyurethane resin soft pad could be revealed clearly in the joint space.The metallic artifacts of artificial prosthesis of FBP group were found in the field of A1~A7,the length of the artifacts were 0.5~2.6mm.The metallic artifacts in the images of FBP group were obviously more than that of IR group.Conclusion:The artifacts of metallic implant could be reduced by IR technique in patients with artificial knee joint replacement examined by DTS.The image quality was obviously improved,which was of great clinical value in the follow up after knee joint replacement.