双层探测器光谱CT使用单能量成像结合金属伪影减少算法去除骨搬移金属伪影的价值  

Value of virtual monoenergetic image from dual-layer spectral detector CT combined with metal artifact reduction algorithm in removal of metal artifacts from bone transport

作　　者：高思齐 赵卫东[2] 张永红[3] 李海涛 刘少皇 高萍 苏琳[1] 薛莉雅 GAO Siqi;ZHAO Weidong;ZHANG Yonghong;LI Haitao;LIU Shaohuang;GAO Ping;SU Lin;XUE Liya(Department of Medical Imaging,Shanxi Medical University,Taiyuan 030001,China;Department of Imaging,Second Hospital of Shanxi Medical University;Department of Orthopedics,Second Hospital of Shanxi Medical University;Second Clinical Medicine College,Shanxi Medical University)

机构地区：[1]山西医科大学医学影像学院,太原030001 [2]山西医科大学第二医院影像科 [3]山西医科大学第二医院骨科 [4]山西医科大学第二临床医学院

出　　处：《山西医科大学学报》2022年第2期244-250,共7页Journal of Shanxi Medical University

摘　　要：目的评价双层探测器光谱CT(dual-layer spectral detector CT,SDCT)使用单能量成像(virtual monoenergetic image,VMI)结合金属伪影减少算法(metal artifact reduction algorithms,MAR)去除骨搬移外固定架伪影的效果,寻找最佳成像点。方法对12例骨搬移术安置环形外固定架患者进行双层探测器光谱CT扫描。扫描图像重建为常规CT图像(conventional image,CI)、VMI图像、MAR图像及VMI+MAR图像,其中VMI、VMI+MAR单能量范围为40~140 keV(每间隔10 keV为一组,共11组)。选定骨搬移牵拉区伪影最重层面及无伪影层面勾画感兴趣区,记录各组CT值、标准差(standard deviation,SD),计算出ΔCT值、伪影指数(artifact index,AI)、伪影移除率(hardening artifact removal rate,BAR),比较各参数在不同图像上的差异。两位放射科医师对各组图像质量采用5分度法主观评分,并对评分结果进行一致性分析。结果与CI相比,110~140 keV VMI、MAR及40~140 keV VMI+MAR图像的ΔCT值显著增加(P<0.05)。MAR、50~140 keV VMI+MAR图像的AI显著减低(P<0.05)。各能级VMI及VMI+MAR图像BAR随能量级增加而增加,且40~140 keV VMI+MAR的BAR高于40~140 keV VMI图像,最高达88.48%。在相同能量级的VMI与VMI+MAR图像之间,VMI+MAR图像的ΔCT值更高、AI更低,差异有统计学意义(P<0.05)。主观评分4分及以上图像为MAR及110~140 keV VMI+MAR图像,两位医师主观评分结果一致性良好。结论使用VMI+MAR可以有效减少骨搬移外固定架产生的金属伪影,且110~140 keV VMI+MAR图像的金属伪影明显减小,140 keV VMI+MAR主客观图像质量最佳。Objective To evaluate the efficacy of virtual monoenergetic images(VMIs)from dual-layer spectral detector CT(SDCT)combined with metal artifact reduction algorithm(MAR)for metal artifact reduction caused by orthogonal circular external fixator of bone transport,and to screen the best imaging point.Methods SDCT scanning was performed in 12 patients undergoing bone transport treatment.Conventional image(CI)and VMI(40-140 keV with 10 keV intervals),MAR and VMI+MAR images were reconstructed.The region of interests was delineated on the images with severe artifacts in the bone extension area and without artifact area.CT value and standard deviation(SD)were recorded,theΔCT,artifact index(AI),hardening artifact removal rate(BAR)were calculated,and the difference between reconstructed setting images was compared.Two radiologists subjectively scored the quality using 5-point Likert scale,and the score consistency was analyzed.Results Compared with CI,theΔCT of 110-140 keV VMI images,MAR image and 40-140 keV VMI+MAR images were significantly increased(P<0.05),and the AI of MAR image and 50-140 keV VMI+MAR images were significantly reduced(P<0.05).The BAR of 40-140 keV VMI+MAR images were higher than that of 40-140 keV VMI images,and the highest removal rate was 88.48%.In the same energy level,ΔCT of VMI+MAR images was higher than that of VMI images,and the AI values of VMI+MAR images were lower(P<0.05).The subjective score of MAR and 110-140 keV VMI+MAR images was 4 points and above.The subjective scores of the two doctors were in good agreement.Conclusion VMI+MAR can effectively reduce the metal artifacts caused by orthogonal circular external fixator of bone transport.In addition,the metal artifacts of 110-140 keV VMI+MAR images are significantly reduced,and 140 keV VMI+MAR image shows the best subjective and objective image quality.

关 键 词：双层探测器光谱CT 单能量成像 金属伪影减少算法 骨搬移 金属伪影 

分 类 号：R445[医药卫生—影像医学与核医学]