能谱成像技术减少口腔修复材料金属伪影的应用价值

The Value of Spectral Imaging in Reducing Dental Restoration Material Artifacts

目的探讨宝石CT能谱成像技术(GSI)在减少口腔修复材料金属伪影的临床价值。方法在相同CT剂量指数(CTDI)条件下,对35例牙齿植入口腔修复材料的患者进行GSI扫描并获得140 k Vp混合能量图像(QC)以及40~140 ke V重组的110个序列单能量图像。由三名高级职称的放射医师对QC图像及单能量图像两种不同成像方式的图像质量差异进行评价并量化分析:选择每例患者伪影较重的两个层面图像进行评价,并分别测量伪影最重层面图像的口腔修复材料周围和邻近无金属伪影层面图像的CT值及噪声值并计算对比噪声比(CNR)、伪影指数(AI);比较两种图像的噪声、AI和CNR值。结果 (1)不同ke V的单能量图像,口腔金属修复材料邻近组织的CNR最佳者为140 ke V图像,其中单能量图像的CNR明显高于QC图像(P<0.01);140 ke V下的单能量图像的噪声最小,并且单能量图像的噪声明显小于QC图像的噪声(P<0.05),同时,随着ke V增加,图像噪声逐渐降低。(2)在选定层面的单能量图像中,AI值随着ke V的升高而逐渐降低,并在140 ke V单能量图像时AI值最小,140 ke V单能量图像的AI值明显小于QC图像的AI值(P<0.01)。(3)单能量图像质量评分随着ke V升高而逐渐降低,也就表示GSI减少口腔修复材料金属伪影的效果越好;100 ke V以上单能量图像的质量优于QC图像的质量(P<0.05)。结论 GSI能明显减少在CT检查图像中口腔金属修复材料周围的金属伪影,提高图像质量并改善口腔金属修复材料邻近组织或病变的显示。

Objective To explore the value of Gemstone Spectral Imaging（ GSI） in reducing metal artifacts in dental restorative materials. Methods 35 patients with dental restoration material implanted into their teeth underwent GSI scan in order to obtain the polychromatic images（ 140 k Vp） and 11 sets of monochromatic images（ 40-140 ke V,interval of 10 ke V） in the same CT dose index（ CTDI）. Subjective image quality of three methods was assessed by 3 radiologists in consensus. CNR of the structure dental restorative materials and noise of background and artifact index（ AI） were calculated.All results were analyzed. Results（ 1） The optimal CNR and noise was acquired at the energy level of 140 ke V monochromatic images in the different ke V monochromatic images,and the CNR and noise at the 140 ke V monochromatic images was obviously better than QC imaging（ P〈0. 01）. Meanwhile,the noise of imaging was gradually reduced with the increase of ke V.（ 2） The value of AI in 140 ke V monochromatic images was the smallest,and reduced gradually with the increase of ke V. The value of AI at the 140 ke V was significantly less than that of QC（ P〈0. 01）.（ 3） The greater the increase of ke V,the lower the scores of imaging quality,the better effect of the spectral imaging in reducing artifacts. The quality of monochromatic images more than 100 ke V is better than polychromatic images（ P〈0. 05）. Conclusion GSI technique could reduce dental restoration material artifacts effectively in CT images,and improve the quality of images and improve the display of tissues adjacent to dental restoration material after implantation.