目的探讨对比去金属伪影高带宽(high bandwidth,HBW)序列与层面编码金属伪影矫正(slice-encoding for metal artifact correction,SEMAC)序列的成像效果,分析SEMAC序列在全膝关节置换术后减低金属伪影的临床应用价值。方法选取24例(30...目的探讨对比去金属伪影高带宽(high bandwidth,HBW)序列与层面编码金属伪影矫正(slice-encoding for metal artifact correction,SEMAC)序列的成像效果,分析SEMAC序列在全膝关节置换术后减低金属伪影的临床应用价值。方法选取24例(30侧膝关节)全膝关节置换术后患者行膝关节MRI扫描,扫描序列包括矢状面HBW序列和SEMAC序列。定量测量两序列金属伪影高信号显著区图像的信噪比(SNR)及对比噪声比(CNR),由2位医师对假体不同部位图像质量进行主观对比评分(5级评分法)。采用配对t检验比较两序列图像SNR及CNR的差异,采用Kappa检验评价2位医师之间图像质量评分的一致性,采用Wilcoxon符号秩和检验比较假体不同部位图像质量的差异。结果24例患者SEMAC序列伪影的SNR及CNR低于HBW序列,差异有统计学意义(P<0.01);2位医师之间图像质量评分的一致性良好,差异有统计学意义(P<0.01);SEMAC序列胫骨平台假体、垫片和股骨髁假体三部分图像质量评分均明显高于HBW序列,差异有统计学意义(P<0.01);SEMAC序列中垫片部评分高于其余两部,差异有统计学意义(P<0.01)。SEMAC序列检查时间(15 min 9 s)较HBW(6 min 47 s)增加8 min 22 s。结论与HBW序列相比,SEMAC序列显示假体三部分图像质量均明显高于HBW序列。SEMAC序列能够很好显示膝关节人工假体,假体金属伪影高信号值明显降低,周围骨质、软组织解剖结构显示清晰,图像变形及模糊情况得到很好改善。使用SEMAC序列能提高假体周围软组织的图像质量,但扫描时间有一定延长。展开更多
Background Magnetic resonance imaging (MRI) is prone to be deformed by artifacts caused by the presence of metallic materials. The aim of this study was to evaluate the artifacts from galvano-ceramic and metal-ceram...Background Magnetic resonance imaging (MRI) is prone to be deformed by artifacts caused by the presence of metallic materials. The aim of this study was to evaluate the artifacts from galvano-ceramic and metal-ceramic crowns in MRI, in order to analyze their influences on diagnostic interpretation of MRI. Methods Galvano-ceramic and metal-ceramic crowns (Bio98, Wiron99, SP-78, BioKC97) were fabricated with the same model. All materials were imaged by means of 1.5T MRI apparatus with three different sequences, T1-weighted spin-echo (T1-weighted SE), T2-weighted spin-echo (T2-weighted SE) and Gradient echo (GE). Mean and standard deviation of distilled water signal intensity (St) around the sample in the region of interest (500 mm^2) enclosing the whole artifacts were determined, and compared for evaluation of the homogeneity of signal intensity. Images around the sample were acquired and evaluated. Results There were statistically significant differences in the values of signal intensity between acrylic resin control and BioKC97, Wiron99 in the three sequences (P〈0.001). The mean values of signal intensity for Bio98, SP-78 were significantly different from that of acrylic resin control (RE) in GE sequence (P〈0.001). No difference was showed between acrylic resin control and galvano-ceramic crown (P 〉0.05). Images showed that the greatest artifact was a 25 mm ring with distortion in Wiron99 in GE sequence. Conclusions This in vitro study suggested that galvano-ceramic crown had no influence on the MRI, while metal-ceramic crowns caused moderate artifacts in the MRI. Therefore, galvano-ceramic restoration is a valuable alternative in dentistry.展开更多
目的:观察4种金属铸造冠磁共振成像(MRI)检查时所产生金属伪影。方法:给实验犬依次佩戴钴铬合金、低钛合金、镍铬合金、纯钛4种试验铸造冠(右上第二前磨牙),分别进行常规3.0 T 6个序列及1.5 T 4个序列磁共振头部扫描,测量4种铸造冠所产...目的:观察4种金属铸造冠磁共振成像(MRI)检查时所产生金属伪影。方法:给实验犬依次佩戴钴铬合金、低钛合金、镍铬合金、纯钛4种试验铸造冠(右上第二前磨牙),分别进行常规3.0 T 6个序列及1.5 T 4个序列磁共振头部扫描,测量4种铸造冠所产生的伪影的最大面积和伪影涉及图像的层数。结果:2种场强下钴铬合金铸造冠所产生的伪影面积最大(P<0.01);1.5 T场强下其他3种合金冠之间差异均无显著性(P>0.05);3.0 T场强下镍铬合金冠伪影大于低钛合金冠和纯钛冠(P<0.05);低钛合金冠与纯钛冠差异无显著性(P>0.05)。在2种场强下和全部扫描序列中,伪影涉及的图像层数均以钴铬合金冠的最多,纯钛金属冠最少,其余2种合金冠相同。结论:钴铬合金伪影程度最大,镍铬合金和低钛合金次之,纯钛在4种金属中伪影程度最小。展开更多
目的比较不同场强不同序列伪影的差异。方法制作钛合金水模,分别在1.5 T和3.0 T MRI扫描仪上采用矢状位快速自旋回波(TSE)-T1、TSE-T2、TSE的短反转时间的反转恢复(STIR)的脂肪抑制、TSE的频率选择饱和法(FS)抑制、梯度回波序列(GRE)/...目的比较不同场强不同序列伪影的差异。方法制作钛合金水模,分别在1.5 T和3.0 T MRI扫描仪上采用矢状位快速自旋回波(TSE)-T1、TSE-T2、TSE的短反转时间的反转恢复(STIR)的脂肪抑制、TSE的频率选择饱和法(FS)抑制、梯度回波序列(GRE)/快速小角度激发(FLASH)、扩散加权成像(DWI)等常用序列扫描。分析扫描得到图像伪影特点及进行伪影大小测量。结果GRE/FLASH序列图像和DWI图像伪影最大,FS抑制序列得到图像伪影比STIR序列图像伪影大,各序列伪影形状也有差别。在不同场强下相同类型序列扫描伪影也不同,高场强伪影明显大于低场强伪影。同一场强不同序列伪影大小不同,同一类型序列3.0 T MRI图像伪影比1.5 T MRI图像伪影要大,差异有统计学意义(P<0.05)。结论可以通过场强选择、序列的选择来减少金属植入物磁共振扫描带来的伪影。展开更多
文摘目的探讨对比去金属伪影高带宽(high bandwidth,HBW)序列与层面编码金属伪影矫正(slice-encoding for metal artifact correction,SEMAC)序列的成像效果,分析SEMAC序列在全膝关节置换术后减低金属伪影的临床应用价值。方法选取24例(30侧膝关节)全膝关节置换术后患者行膝关节MRI扫描,扫描序列包括矢状面HBW序列和SEMAC序列。定量测量两序列金属伪影高信号显著区图像的信噪比(SNR)及对比噪声比(CNR),由2位医师对假体不同部位图像质量进行主观对比评分(5级评分法)。采用配对t检验比较两序列图像SNR及CNR的差异,采用Kappa检验评价2位医师之间图像质量评分的一致性,采用Wilcoxon符号秩和检验比较假体不同部位图像质量的差异。结果24例患者SEMAC序列伪影的SNR及CNR低于HBW序列,差异有统计学意义(P<0.01);2位医师之间图像质量评分的一致性良好,差异有统计学意义(P<0.01);SEMAC序列胫骨平台假体、垫片和股骨髁假体三部分图像质量评分均明显高于HBW序列,差异有统计学意义(P<0.01);SEMAC序列中垫片部评分高于其余两部,差异有统计学意义(P<0.01)。SEMAC序列检查时间(15 min 9 s)较HBW(6 min 47 s)增加8 min 22 s。结论与HBW序列相比,SEMAC序列显示假体三部分图像质量均明显高于HBW序列。SEMAC序列能够很好显示膝关节人工假体,假体金属伪影高信号值明显降低,周围骨质、软组织解剖结构显示清晰,图像变形及模糊情况得到很好改善。使用SEMAC序列能提高假体周围软组织的图像质量,但扫描时间有一定延长。
文摘Background Magnetic resonance imaging (MRI) is prone to be deformed by artifacts caused by the presence of metallic materials. The aim of this study was to evaluate the artifacts from galvano-ceramic and metal-ceramic crowns in MRI, in order to analyze their influences on diagnostic interpretation of MRI. Methods Galvano-ceramic and metal-ceramic crowns (Bio98, Wiron99, SP-78, BioKC97) were fabricated with the same model. All materials were imaged by means of 1.5T MRI apparatus with three different sequences, T1-weighted spin-echo (T1-weighted SE), T2-weighted spin-echo (T2-weighted SE) and Gradient echo (GE). Mean and standard deviation of distilled water signal intensity (St) around the sample in the region of interest (500 mm^2) enclosing the whole artifacts were determined, and compared for evaluation of the homogeneity of signal intensity. Images around the sample were acquired and evaluated. Results There were statistically significant differences in the values of signal intensity between acrylic resin control and BioKC97, Wiron99 in the three sequences (P〈0.001). The mean values of signal intensity for Bio98, SP-78 were significantly different from that of acrylic resin control (RE) in GE sequence (P〈0.001). No difference was showed between acrylic resin control and galvano-ceramic crown (P 〉0.05). Images showed that the greatest artifact was a 25 mm ring with distortion in Wiron99 in GE sequence. Conclusions This in vitro study suggested that galvano-ceramic crown had no influence on the MRI, while metal-ceramic crowns caused moderate artifacts in the MRI. Therefore, galvano-ceramic restoration is a valuable alternative in dentistry.
文摘目的:观察4种金属铸造冠磁共振成像(MRI)检查时所产生金属伪影。方法:给实验犬依次佩戴钴铬合金、低钛合金、镍铬合金、纯钛4种试验铸造冠(右上第二前磨牙),分别进行常规3.0 T 6个序列及1.5 T 4个序列磁共振头部扫描,测量4种铸造冠所产生的伪影的最大面积和伪影涉及图像的层数。结果:2种场强下钴铬合金铸造冠所产生的伪影面积最大(P<0.01);1.5 T场强下其他3种合金冠之间差异均无显著性(P>0.05);3.0 T场强下镍铬合金冠伪影大于低钛合金冠和纯钛冠(P<0.05);低钛合金冠与纯钛冠差异无显著性(P>0.05)。在2种场强下和全部扫描序列中,伪影涉及的图像层数均以钴铬合金冠的最多,纯钛金属冠最少,其余2种合金冠相同。结论:钴铬合金伪影程度最大,镍铬合金和低钛合金次之,纯钛在4种金属中伪影程度最小。
文摘目的比较不同场强不同序列伪影的差异。方法制作钛合金水模,分别在1.5 T和3.0 T MRI扫描仪上采用矢状位快速自旋回波(TSE)-T1、TSE-T2、TSE的短反转时间的反转恢复(STIR)的脂肪抑制、TSE的频率选择饱和法(FS)抑制、梯度回波序列(GRE)/快速小角度激发(FLASH)、扩散加权成像(DWI)等常用序列扫描。分析扫描得到图像伪影特点及进行伪影大小测量。结果GRE/FLASH序列图像和DWI图像伪影最大,FS抑制序列得到图像伪影比STIR序列图像伪影大,各序列伪影形状也有差别。在不同场强下相同类型序列扫描伪影也不同,高场强伪影明显大于低场强伪影。同一场强不同序列伪影大小不同,同一类型序列3.0 T MRI图像伪影比1.5 T MRI图像伪影要大,差异有统计学意义(P<0.05)。结论可以通过场强选择、序列的选择来减少金属植入物磁共振扫描带来的伪影。