摘要
目的:通过体模实验,探讨能谱CT单能量成像结合降低金属植入物伪影(MAR)技术的应用价值。方法和材料:利用环氧树脂制成的定量标准体模,在其周围8个标准圆柱形筒内注入不同浓度的碘溶液各20mL,分别模拟金属植入物周围人体不同组织器官的密度。中间圆筒内注入氯化钠溶液,内置弹簧圈。将标准体模行能谱CT扫描,根据扫描模式不同,分A和B两组,A组采用常规CT扫描模式获得常规混合能量CT图像;B组采用能谱扫描模式,扫描后数据采用能谱分析软件获得3组图像,分别为单纯MAR图像(68keV单能量)、40~140keV单能量图像(MonoE)、MAR+(40~140keV)MonoE图像。四组图像中,弹簧圈周围均可见到条形高密度伪影和低密度伪影,分别测量记录伪影区的CT值和SD值,计算伪影指数、硬化伪影去除率;采用ANOVA检验及配对t检验统计方法对A和B组图像的伪影指数、硬化伪影去除率进行统计分析。结果:与常规混合能量CT图像比较,对于高密度伪影,MAR、MonoE、MAR+MonoE图像伪影指数均减小,差异有统计学意义;对于低密度伪影,MAR、MonoE、MAR+MonoE图像伪影指数均减小,差异有统计学意义。MAR图像高低密度伪影的硬化伪影去除率分别为82%和92%;MonoE和MAR+MonoE图像的高低密度伪影的硬化伪影去除率随着单能量级别的递增,硬化伪影去除率逐级增大,其中MAR+140keV MonoE图像高低密度伪影的硬化伪影去除率最高。结论:能谱CT使用MAR、MonoE和MAR+MonoE重建方法均可不同程度的减少金属植入物伪影。三种方法中使用MAR+MonoE重建方法降低金属伪影效果最好。
Purpose:To evaluate the utility of monochromatic imaging combined with metal artifacts reduction(MAR)for metal artifacts reduction of embolization coil implants using Quantitative Standard Pulsating Phantom with spectral computed tomography.Method and materials:Iodine solutions with eight different concentrations were prepared with different mix ratios of iohexol and sodium chloride.20mL of these concentrations of iodine solutions were contained in eight tubes and inserted into the Quantitative Standard Pulsating Phantom to simulate different degrees of enhancement in organs of human anatomy.The embolization coil with a diameter of 8mm was placed in an intermediate cylinder of the QSP that contains sodium chloride solution.Two scan protocols were performed using spectral CT:Group A(conventional CT scan mode);Group B adopts Gemstone Spectral Imaging mode and after a post-processing workstation to obtain one set of 120kVp images,MAR images(68keV),11 sets of monochromatic images(40-140keV,interval of 10keV),11 sets of MonoE+MAR images.The CT values and SD values of artifacts areas are measured respectively.Calculation the artifact index of the region of interest and beam hardening artifact reduction rate.The ANOVA test and Paired T test was used to compare the artifact index and beam hardening artifact reduction rate of the group A and B of images.The difference was statistically significant at P<0.05.Results:Compared with conventional CT images,the high and low density artifacts artifact index of MAR image,MonoE images,MonoE+MAR images were all reduced,P<0.05,and the differences were statistically significant.The high and low density artifacts beam hardening artifact reduction rate of MAR images were 82%,92%;High and low density artifact beam hardening artifact reduction rate of MonoE,MAR+MonoE images increases with single energy enhanced,while MAR+140keV MonoE image were highest.Conclusion:Spectral CT using the MAR,MonoE,and MAR+MonoE reconstruction methods can reduce metal implant artifacts to varying degrees.The MAR+MonoE reconstruction method in the three methods is the best way to reduce metal artifacts.
作者
赵晴晴
孙小丽
李希
王燕文
柳维娜
段永利
王仁贵
ZHAO Qingqing;SUN Xiaoli;LI Xi;WANG Yanwen;LIU Weina;DUAN Yongli;WANG Rengui(Department of Radiology,Beijing Shijitan Hospital,Capital Medical University,Beijing 100038,China)
出处
《CT理论与应用研究(中英文)》
2019年第5期529-539,共11页
Computerized Tomography Theory and Applications
基金
国家自然科学基金(61876216)
首都医科大学附属北京世纪坛医院课题(2018-q01)
关键词
能谱CT
单能量成像
金属植入物伪影
spectral CT
monochromatic imaging
metal artifacts reduction(MAR)