Metal artifact reduction using virtual monochromatic images for patients with pedicle screws implants on CT
Metal artifact reduction using virtual monochromatic images for patients with pedicle screws implants on CT
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DOI：
10.1007/s00586-015-4053-4
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发表时间：
2016-06-01
影响因子：
2.8
通讯作者：
Liu, Yi Jun
中科院分区：
文献类型：
--
作者：
Dong, Yue;Shi, Ai Jun;Liu, Yi Jun
为评价频谱CT在椎弓根螺钉金属伪影减少中的作用，对45例患者共119对椎弓根螺钉进行了频谱CT检查。获得了1组常规多色图像(140kVP)和9组虚拟单色图像(60-140keV)。测量种植体周围12个部位和匀质脂肪上1个部位CT数的标准差(SD)，生成伪影指数(AI)。目的采用独立t检验和配对样本t检验对AI、CT数和SD值进行评价。两位放射科医师独立评审图像质量，图像质量的主观评分采用Wilcoxon符号等级检验和Kappa分析，所有区域的伪影指数(AI)均随着Kev的增加而降低。100~140keV的AI低于140 KVP的AI。在120keV下，椎弓根水平与椎弓根水平对腰大肌和椎管的CT值无显著差异，但SD值在两者之间有显著差异。100keV~140keV图像的主观得分高于140keV的图像，其中120keV的两个观察者的主观得分最高，观察者间的一致性好(kappa=0.889)。高能水平的虚拟单色图像去除金属伪影的效果很好，120keV的单色图像提供了准确的CT数和良好的主观评分。
To evaluate the effect of spectral CT for metal artifact reduction in patients with pedicle screw.45 patients with 119 pairs of pedicle screws underwent spectral CT examination. One set of conventional (140 kVp) polychromatic image and nine sets of virtual monochromatic images (60-140 keV) were obtained. The standard deviation (SD) of CT number in 12 locations around the implant and 1 on homogenous fat was measured to generate artifact index (AI). Objective assessment including AI, CT number and SD value was performed with independent t test and paired sample t test. Two radiologists independently reviewed the image quality, and Wilcoxon signed-rank test and kappa analysis were used for the subjective scores of image quality.The artifact index (AI) of all the regions decreased as keV increased. AIs of 100-140 keV were lower than that of 140 kVp images. At 120 keV there was no significant difference in CT numbers of psoas major muscle and vertebral canal between pedicle screw level and pedicle level, but a significant difference in SD value was determined between the two levels. The subjective scores at 100-140 keV were higher than the images at 140 kVp, and the highest subjective score of two observers and excellent interobserver agreement were found at 120 keV (kappa = 0.889).Virtual monochromatic images at high-energy levels have a well-concordant effect of removing metal artifacts, and 120 keV monochromatic images provided an accurate CT number and good subjective score.