目的 探讨CT能谱成像技术(GSI)去除眼眶金属植入物伪影的应用效果。方法 对32例眼眶外伤金属植入物修复术后患者进行CT能谱成像,获得140 kVp的混合能量图像;应用能谱分析软件,获得40～140 keV(以10 keV为间距)共11组单能量图像。由3名放射医师采用双盲法对2种图像的质量进行主观评价。选取每种图像中伪影最明显层面及无伪影层面,测量感兴趣区(ROI)的CT值和噪声值(SD),并计算对比噪声比(CNR)和伪影指数(AI)。比较单能量图像和混合能量图像的SD、CNR、AI值。结果 在11组单能量图像中,110 keV图像的噪声值(SD)和伪影指数(AI)最小,对比噪声比(CNR)最佳。相比混合能量图像,去除眼眶金属植入物伪影的效果明显,图像质量显著提高。结论CT能谱成像技术能明显减少金属伪影的干扰,显著提高眼眶术后结构的显示能力。110 keV是眼眶金属植入患者图像质量最佳的单能量成像点。

Objective To evaluate the practical value of gemstone spectral imaging(GSI)in reducing the metal artifacts of orbital implants.Methods GSI examination were performed in 32 patients with metal implants of orbit,and the polychromatic images(140 kVp)were obtained.Gemstone spectral imaging(GSI)viewer was used to obtain 11 sets of monochromatic images(40-140 keV with interval of 10 keV).Subjective image quality of two methods was assessed by 3 radiologists in consensus.CT value and noise value(SD)of ROI were measured at the most obvious and non-artifact level of each image,and contrast noise ratio(CNR)and artifact index(AI)were calculated.The SD,CNR and AI values were compared between polychromatic images and monochromatic images.Results Among the 11 sets of monochromatic images,the noise value(SD)and artifact index(AI)of 110 keV images were the smallest,and the contrast noise ratio(CNR)was the best.Compared with the polychromatic images,the artifacts of orbital metal implants were removed significantly,and the image quality was improved significantly.Conclusion Gemstone spectral CT can effectively reduce artifacts of orbital metal implants and will provide high image quality in the area of metal implants.110 keV is the best monochromatic imaging point for the image quality of patients with orbital metal implant.