能谱成像技术在减除脊柱金属植入物伪影方面的临床应用价值
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摘要
目的：探讨宝石CT能谱成像技术在去除脊柱金属植入物放射状伪影方面的最佳的成像的单能量点，并评价其临床应用价值。
方法：对20例在我院行脊柱外科手术，并植入金属固定物的患者行宝石CT能谱扫描，扫描后获得（120Kvp）混合能量图像及70Kev单能量图像。用能谱分析软件（GSI viewer）进行分析，在40-140Kev（间距10Kev）重建11种单能量图像，然后选取最佳单能量图像行金属伪影消除重建（Metal-Artifacts Reduction System，MARs），获得MARs能谱图像(110Kev单能量+MARs图像）。由本科室3名高年资放射科诊断医师参照使用4分量表[1]，来对采集的图像质量高低进行主观目测评分；测量的放射状伪影为植入椎弓根螺钉前端伪影长度以评价其伪影轻重程度；于每组图像中选取伪影最重层面(A)行两次SD值测定记录为SD1、SD2，同时选择无或少伪影层面（B）行SD值测定记录为SD0，作为正常对照。对所获得数据采用spps17.0统计学软件包，进行配对t检验数据分析。
结果：在11种单能量图像组中，随着Kev的增加，伪影长度将逐渐缩短，在110-140Kev区间伪影长度接近于零，且在此区间各组间伪影长度无明显差异；110Kev单能量图像组的伪影指数和噪声值最小，主观评分最高，因此所有20例患者的图像均于110Kev行MARs重建。MARs能谱图像组（110Kev单能量+MARS图像）与混合能量图像组的主观评分及伪影长度之间均存在显著性差异（P=0.000<0.05），即MARs单能量图像组的脊柱金属植入物放射状伪影与混合能量组相比，伪影程度明显降低，图像质量较混合能量图像组显著提高。MARs能谱图像组与最佳单能量图像组的伪影长度及噪声值之间存在差异，即MARs能谱图像组较单能量图像组的图像质量有所提高。
结论：在钛合金材质的脊柱金属植入物患者的单能量图像组中，110Kev为图像质量最佳的单能量成像点。在减除钛合金材质的脊柱金属植入物伪影时应联合应用单能量技术和MARs技术。宝石CT能谱成像技术能够显著减少脊柱金属植入物的伪影，使CT图像的质量明显提高，具有较高的临床应用价值。
Objective:To evaluate the practical value of gemstone spectral imaging(GSI)in reducing the metal artifacts of spine,and to find the best monochromatic imaging of image quality.
Methods:GSI examination were performed to twenty patients with metal implants of spine,70Kev set of monochromatic images and blend energy images were acquired at the same time. Gemstone spectral imaging (GSI) viewer was used to obtain11sets of monochromatic imagings(40—140keV with interval of10keV) and110keV+MARs images.Three radiologists reviewed all images respectively and assessed the image quality visually using4-point scale.The lengths of the artifacts emanating from the anterior tips of the screw were used to evaluate the degree of artifact.Images with heaviest artifacts level (A) and less or no artifacts level (B) were selected SD value of ROI were measured and the artifact index (AI) was calculated. Statistical analysis was accomplished with SPSS17.0soft package.
Results:In Of the11sets of monochromatic images,110keV set had the highest score of image quality,the lengths of artifacts were lowest.There were significant statistical differences between energy spectral images and blend energy images(P<0.05), that is to say, the image quality of energy spectral were significantly better than those of blend energy images.
Conclusion:Patients with metal implants of spine,110keV was the best point for quality of monochromatic imaging.Gemstone spectral CT can effectively reduce artifacts of spine metal implants and will provide high image quality in the area with metal implants.
方法：对20例在我院行脊柱外科手术，并植入金属固定物的患者行宝石CT能谱扫描，扫描后获得（120Kvp）混合能量图像及70Kev单能量图像。用能谱分析软件（GSI viewer）进行分析，在40-140Kev（间距10Kev）重建11种单能量图像，然后选取最佳单能量图像行金属伪影消除重建（Metal-Artifacts Reduction System，MARs），获得MARs能谱图像(110Kev单能量+MARs图像）。由本科室3名高年资放射科诊断医师参照使用4分量表[1]，来对采集的图像质量高低进行主观目测评分；测量的放射状伪影为植入椎弓根螺钉前端伪影长度以评价其伪影轻重程度；于每组图像中选取伪影最重层面(A)行两次SD值测定记录为SD1、SD2，同时选择无或少伪影层面（B）行SD值测定记录为SD0，作为正常对照。对所获得数据采用spps17.0统计学软件包，进行配对t检验数据分析。
结果：在11种单能量图像组中，随着Kev的增加，伪影长度将逐渐缩短，在110-140Kev区间伪影长度接近于零，且在此区间各组间伪影长度无明显差异；110Kev单能量图像组的伪影指数和噪声值最小，主观评分最高，因此所有20例患者的图像均于110Kev行MARs重建。MARs能谱图像组（110Kev单能量+MARS图像）与混合能量图像组的主观评分及伪影长度之间均存在显著性差异（P=0.000<0.05），即MARs单能量图像组的脊柱金属植入物放射状伪影与混合能量组相比，伪影程度明显降低，图像质量较混合能量图像组显著提高。MARs能谱图像组与最佳单能量图像组的伪影长度及噪声值之间存在差异，即MARs能谱图像组较单能量图像组的图像质量有所提高。
结论：在钛合金材质的脊柱金属植入物患者的单能量图像组中，110Kev为图像质量最佳的单能量成像点。在减除钛合金材质的脊柱金属植入物伪影时应联合应用单能量技术和MARs技术。宝石CT能谱成像技术能够显著减少脊柱金属植入物的伪影，使CT图像的质量明显提高，具有较高的临床应用价值。
Objective:To evaluate the practical value of gemstone spectral imaging(GSI)in reducing the metal artifacts of spine,and to find the best monochromatic imaging of image quality.
Methods:GSI examination were performed to twenty patients with metal implants of spine,70Kev set of monochromatic images and blend energy images were acquired at the same time. Gemstone spectral imaging (GSI) viewer was used to obtain11sets of monochromatic imagings(40—140keV with interval of10keV) and110keV+MARs images.Three radiologists reviewed all images respectively and assessed the image quality visually using4-point scale.The lengths of the artifacts emanating from the anterior tips of the screw were used to evaluate the degree of artifact.Images with heaviest artifacts level (A) and less or no artifacts level (B) were selected SD value of ROI were measured and the artifact index (AI) was calculated. Statistical analysis was accomplished with SPSS17.0soft package.
Results:In Of the11sets of monochromatic images,110keV set had the highest score of image quality,the lengths of artifacts were lowest.There were significant statistical differences between energy spectral images and blend energy images(P<0.05), that is to say, the image quality of energy spectral were significantly better than those of blend energy images.
Conclusion:Patients with metal implants of spine,110keV was the best point for quality of monochromatic imaging.Gemstone spectral CT can effectively reduce artifacts of spine metal implants and will provide high image quality in the area with metal implants.
引文
[1]宁国庆.能谱成像技术去除金属伪影的临床价值.医学影像学杂志,2011,29(9)：1425-1428.[2]Blum A.Volumic and multislice CT:principles,applications and future prospects.[J].JBR-BTR,2002,85(2):82-99.[3]Ohashi KE,Khoury GY,Bennett DL,Restrepo JM,Berbaum KS.Orthopedic hardw are complications diagnosed with multi-detector row CT.[J].Radiology,2005,237(2):570-577.[4]Dalal T, Kalra MK, Rizzo SM, Schmidt B, Suess C, Flohr T,et al. Metallic prosthes is technique to avoid increase in CT radiation dose with automatic tube current modulation in a phantom and patients.[J]. Radiology,2005,236(2):671-675.[5]王万勤.能谱CT最佳单能量成像去除体模对比剂硬化伪影及图像噪声.中国医学影像技术,2011,27(11)：2349-2352.[6]王健.宝石CT的技术突破和临床应用.国际放射医学核医学杂志,2009,33(2)：127.[7]徐树山,王秀珍编.热力学及统计物理.北京师范大学出版社,1987.363.[8]汪家旺,李宝春,张廉良.矩阵曝光量对CT图像噪声的影响.中华放射学杂志,1996,30(6)：276.[9]Barrett JF,Keat. Artifacts in CT:recognition and avoidance.[J]. Radiographics,2004,24(6):1679-1691.[10]赖胜圣,杨蕊梦.CT图像伪影及处理方法.数理医药学杂志,2009,2(9)：206-210.[11]周泽俊,胡永胜,高斌,等.多层螺旋CT图像伪影的分析.中国CT和MRI杂志.2008,4(7)：72-73.[12]谷建伟,张丽,陈志强,等.工业CT图像的伪影成因和校正方法综述.CT理论与应用研究,2005,03(14)：108-111.[13]Bal M,Spies L.Metal artifact reduction in CT using tissue-class modeling and adaptive prefiltering.[J].Medical Physics,2006,33(8):2852-2859.[14]Yu H, Zeng K,Bharkhada DK,et al.Asegmentation-based method for metal artifact reduction.[J].Acad Radiol,2007,14(4):495-504.[15]Xia D,Roeske JC,Yu L,et al.Ahybrid approach to reducing computed tomography metal artifacts in intracavitary brachytherapy.[J].Brachytherapy,2005,4(1):18-23.[16]黄桂玲,孙戈新,刘剑平,等.心脏CT成像低辐射剂量技术的进展.中国老年医学杂志,2010,14(30)：2081-2083.[17]lin XZ,Miao F,Li JY,etal.High-definition CT gemstone spectral imaging of the brain:initila results of selecting optimal mono-chromatic image for beam-hardening artifacts and image noise reduction.[J].Comput Assist Tomogr,2011,35(2):294-297.
[18]白玫,郑钧正.多排(层)螺旋CT的辐射剂量表达及影响因素探讨.辐射防护,2008,28(1):2.
[19]路鹤晴,朱国英,卓维海,等.医用X射线CT辐射剂量影响因素研究.上海医学影像,2008,17(2):94.[1]Blum A.Volumic and multislice CT:principles,applications and future prospects.[J].JBR-BTR,2002,85(2):82-99.[2]Ohashi KE,Khoury GY,Bennett DL,Restrepo JM,Berbaum KS.Orthopedic hardw are complications diagnosed with multi-detector row CT.[J].Radiology,2005;237(2):570-577.[3]Dalal T, Kalra MK, Rizzo SM, Schmidt B, Suess C, Flohr T,et al. Metallic prosthes is technique to avoid increase in CT radiation dose with automatic tube current modulation in a phantom and patients.[J].Radiology,2005,236(2):671-675.[4]王健.宝石CT的技术突破和临床应用.国际放射医学核医学杂志,2009,33(2)：127.[5]黄大同.CT影像噪声的检测与评价.中国医学影像技术,1994,10(1)：57-58.[6]沈天真.中枢神经系统计算机体层摄影(CT)和磁共振成像(MRI).上海医科大学出版社,1991,5-7.[7]Barrett JF,Keat N. Artifacts in CT:recognition and avoidance.[J]. Radiographics,2004,24(6):1679-1691.[8]赖胜圣,杨蕊梦.CT图像伪影及处理方法.数理医药学杂志,2009,2：206-210.[9]谷建伟,张丽,陈志强,等.工业CT图像的伪影成因和校正方法综述.CT理论与应用研究,2005,03(14)：108-111.[10]Bal M,Spies L.Metal artifact reduction in CT using tissue-class modeling and adaptive prefiltering.[J].Medical Physics,2006,33(8):2852-2859.[11]Yu H,Zeng K,Bharkhada DK,et al.Asegmentation-based method for metal artifact reduction.[J].Acad Radiol,2007,14(4):495-504.[12]Xia D,Roeske JC,Yu L,et al.Ahybrid approach to reducing computed tomography metal artifacts in intracavitary brachytherapy.[J].Brachytherapy,2005,4(l):18-23.[13]黄桂玲,孙戈新,刘剑平,等.心脏CT成像低辐射剂量技术的进展.中国老年医学杂志,2010,14(30)：2081-2083.[14]lin XZ,Miao F,Li JY,etal.High-definition CT gemstone spectral imaging of the brain:initila results of selecting optimal mono-chromatic image for beam-hardening artifacts and image noise reduction.[J].Comput Assist Tomogr,2011,35(2):294-297.[15]徐树山,王秀珍编.热力学及统计物理.北京师范大学出版社,1987.363.[16]汪家旺,李宝春,张廉良.矩阵曝光量对CT图像噪声的影响.中华放射学杂志,1996,30(7)：276.[17]刘占存,王立军,吴继光.CT技术发明的历史回顾.首都师范大学学报(自然科学版),2008,43(3)：31-36.[18]郑国祥.浅谈CT技术的发展与应用.医药世界,2007,12(1)：94.[19]童双立.多层螺旋CT的新进展.CT理论与应用研究,2005,31(4)：52-55.[20]陈群英,吕玉玲,张西亚.CT探测器技术特性与新材质的临床应用.生物医学工程与临床,2010,19(1)：81-84.[21]王革,俞恒永,勃鲁努,德曼,等.X线CT研究与发展之展望.中国医疗器具杂志,2008,32(3)：157-167.[22]Kanamaru H,Sato Y,Takayama T,et al. Assessment of coronary artery abnormalities by multislice spiral computed tomography in adolescents and young adults with Kawsaki disease.[J].AmJ Cardiol,2005,95(4):522.[23]Hoffmann MH,Shi H,Schmitz BL.Noninvasive coronary angiography with multislice computed tomography.[J]JAMA,2005,29(3):2471.[24]Scheffel H,Alkadhi H,Plass A,et al. Accuracy of dual source CT coronary angiography;first experience in high pretest probability population without heart rate control.[J].Eur Radiol,2006,16(12):2739-2747.
[18]白玫,郑钧正.多排(层)螺旋CT的辐射剂量表达及影响因素探讨.辐射防护,2008,28(1):2.
[19]路鹤晴,朱国英,卓维海,等.医用X射线CT辐射剂量影响因素研究.上海医学影像,2008,17(2):94.[1]Blum A.Volumic and multislice CT:principles,applications and future prospects.[J].JBR-BTR,2002,85(2):82-99.[2]Ohashi KE,Khoury GY,Bennett DL,Restrepo JM,Berbaum KS.Orthopedic hardw are complications diagnosed with multi-detector row CT.[J].Radiology,2005;237(2):570-577.[3]Dalal T, Kalra MK, Rizzo SM, Schmidt B, Suess C, Flohr T,et al. Metallic prosthes is technique to avoid increase in CT radiation dose with automatic tube current modulation in a phantom and patients.[J].Radiology,2005,236(2):671-675.[4]王健.宝石CT的技术突破和临床应用.国际放射医学核医学杂志,2009,33(2)：127.[5]黄大同.CT影像噪声的检测与评价.中国医学影像技术,1994,10(1)：57-58.[6]沈天真.中枢神经系统计算机体层摄影(CT)和磁共振成像(MRI).上海医科大学出版社,1991,5-7.[7]Barrett JF,Keat N. Artifacts in CT:recognition and avoidance.[J]. Radiographics,2004,24(6):1679-1691.[8]赖胜圣,杨蕊梦.CT图像伪影及处理方法.数理医药学杂志,2009,2：206-210.[9]谷建伟,张丽,陈志强,等.工业CT图像的伪影成因和校正方法综述.CT理论与应用研究,2005,03(14)：108-111.[10]Bal M,Spies L.Metal artifact reduction in CT using tissue-class modeling and adaptive prefiltering.[J].Medical Physics,2006,33(8):2852-2859.[11]Yu H,Zeng K,Bharkhada DK,et al.Asegmentation-based method for metal artifact reduction.[J].Acad Radiol,2007,14(4):495-504.[12]Xia D,Roeske JC,Yu L,et al.Ahybrid approach to reducing computed tomography metal artifacts in intracavitary brachytherapy.[J].Brachytherapy,2005,4(l):18-23.[13]黄桂玲,孙戈新,刘剑平,等.心脏CT成像低辐射剂量技术的进展.中国老年医学杂志,2010,14(30)：2081-2083.[14]lin XZ,Miao F,Li JY,etal.High-definition CT gemstone spectral imaging of the brain:initila results of selecting optimal mono-chromatic image for beam-hardening artifacts and image noise reduction.[J].Comput Assist Tomogr,2011,35(2):294-297.[15]徐树山,王秀珍编.热力学及统计物理.北京师范大学出版社,1987.363.[16]汪家旺,李宝春,张廉良.矩阵曝光量对CT图像噪声的影响.中华放射学杂志,1996,30(7)：276.[17]刘占存,王立军,吴继光.CT技术发明的历史回顾.首都师范大学学报(自然科学版),2008,43(3)：31-36.[18]郑国祥.浅谈CT技术的发展与应用.医药世界,2007,12(1)：94.[19]童双立.多层螺旋CT的新进展.CT理论与应用研究,2005,31(4)：52-55.[20]陈群英,吕玉玲,张西亚.CT探测器技术特性与新材质的临床应用.生物医学工程与临床,2010,19(1)：81-84.[21]王革,俞恒永,勃鲁努,德曼,等.X线CT研究与发展之展望.中国医疗器具杂志,2008,32(3)：157-167.[22]Kanamaru H,Sato Y,Takayama T,et al. Assessment of coronary artery abnormalities by multislice spiral computed tomography in adolescents and young adults with Kawsaki disease.[J].AmJ Cardiol,2005,95(4):522.[23]Hoffmann MH,Shi H,Schmitz BL.Noninvasive coronary angiography with multislice computed tomography.[J]JAMA,2005,29(3):2471.[24]Scheffel H,Alkadhi H,Plass A,et al. Accuracy of dual source CT coronary angiography;first experience in high pretest probability population without heart rate control.[J].Eur Radiol,2006,16(12):2739-2747.