探讨IQon双层探测器光谱CT在经颈静脉肝内门体分流术（TIPS）后支架评估中的最佳单能级图像。

回顾性分析2020年3月至2020年9月在中山大学附属第三医院行上腹部光谱CT检查的30例门静脉高压症TIPS术后随访患者影像学资料。其中男18例，女12例；年龄38~72岁，中位年龄46岁。患者均签署知情同意书，符合医学伦理学规定。采用门静脉期光谱CT数据在后处理工作站重建出40~100 keV（间隔10 keV）、100~200 keV（间隔20 keV）单能级图像。在常规图像和12组单能级图像上进行支架曲面重建，测量管腔内及同层竖脊肌的CT值和噪声值。计算13组图像的对比噪声比（CNR）。两名10年以上诊断经验的医师对图像的腔内伪影程度及诊断信心进行主观评分。图像质量评价指标比较采用单因素方差分析和LSD-t检验，或Friedman检验。图像质量主观评价的一致性采用Kappa检验。

随着能级降低，TIPS支架管腔内CT值逐渐升高，其中80~200 keV能级图像的CT值均明显低于常规图像（LSD-t=-2.6，-5.3，-7.1，-9.2，-10.4，-11.1，-11.6，-12.1；P<0.05）；40~60 keV能级图像的管腔内CT值明显高于常规图像（LSD-t=36.7，18.5，7.8；P<0.05）。随着能级降低，管腔内SD值逐渐升高，其中80~200 keV能级图像的SD值均明显低于常规图像（LSD-t=-4.4，-5.1，-6.0，-6.6，-6.1，-6.3，-6.3，-6.3；P<0.05）；40 keV能级图像的管腔内SD值明显高于常规图像（LSD-t=4.5，P<0.05）。随着能级降低，支架的CNR逐渐升高。其中90~200 keV能级图像的支架CNR值均明显低于常规图像（LSD-t=-2.2，-3.6，-5.4，-6.1，-6.0，-6.1，-6.2；P<0.05）；40~70 keV能级图像的支架CNR值均明显高于常规图像（LSD-t=22.7，16.7，8.4，3.4；P<0.05）。各组图像诊断信心评分显示，90~140 keV组的主观评分均明显高于常规图像组（χ²=292.1，302.8，343.7，270.8；P<0.05），其中120 keV组评分最高，两位医师的主观评分一致性好（κ=0.81）。腔内伪影主观评分显示，90~200 keV组的主观评分均明显高于常规组（χ²=207.2，240.1，260.5，281.6，302.0，322.4，322.6；P<0.05），两位医师的主观评分一致性好（κ=0.85）。

基于光谱CT重建的单能级图像能有效减少TIPS术后支架腔内伪影，提高诊断信心，并提升图像质量，其中120 keV单能级图像为最佳的单能级图像。

To investigate the optimal single-energy image of IQon dual-layer spectral detector CT in stent evaluation after transjugular intrahepatic portosystemic shunt (TIPS).

Imaging data of 30 patients with portal hypertension who underwent spectral CT scan of the upper abdomen in the Third Affiliated Hospital of Sun Yat-sen University from March to September 2020 were retrospectively analyzed. Among them, 18 patients were male and 12 female, aged from 38 to 72 years, with a median age of 46 years. The informed consents of all patients were obtained and the local ethical committee approval was received. The single-energy images of 40-100 keV (interval of 10 keV) and 100-200 keV (interval of 20 keV) were reconstructed at the post-processing workstation using the spectral CT data of portal venous phase. The stent curved planar reconstruction was performed with the conventional images and 12 groups of single-energy images. The CT value and noise value in the lumen and erector spinae of the same layer were measured. The contrast-to-noise ratio (CNR) of images of 13 groups was calculated. The degree of intraluminal artifacts and diagnostic confidence were scored subjectively by 2 radiologists with more than10 years' experience. The image quality evaluation indexes were compared by one-way ANOVA, LSD-t test or Friedman test. The consistency of subjective evaluation of image quality was assessed by Kappa test.

With the decrease of energy level, the intraluminal CT value of TIPS stent was gradually increased. The CT values of 80-200 keV images were significantly lower than those of conventional images (LSD-t=-2.6, -5.3, -7.1, -9.2, -10.4, -11.1, -11.6, -12.1; P<0.05). The intraluminal CT values of 40-60 keV images were significantly higher than those of conventional images (LSD-t=36.7, 18.5, 7.8; P<0.05). With the decrease of energy level, the intraluminal SD value was gradually increased. The SD values of 80-200 keVimages were significantly lower than those of conventional images (LSD-t=-4.4, -5.1, -6.0, -6.6, -6.1, -6.3, -6.3, -6.3; P<0.05). The intraluminal SD value images of 40 keV was significantly higher than those of conventional images (LSD-t=4.5, P<0.05). With the decrease of energy level, the CNR of stent was gradually increased. The stent CNR values of 90-200 keV images were significantly lower than those of conventional images (LSD-t=-2.2, -3.6, -5.4, -6.1, -6.0, -6.1, -6.2; P<0.05). The stent CNR values of 40-70 keV images were significantly higher than those of conventional images (LSD-t=22.7, 16.7, 8.4, 3.4; P<0.05). The diagnostic confidence score of each group showed that the subjective scores in 90-140 keV group were significantly higher than those in conventional image group (χ²=292.1, 302.8, 343.7, 270.8; P<0.05). The subjective score of 120 keV group was the highest. The consistency of subjective scores betweentwo radiologists was high (κ=0.81). For the subjective score of intraluminal artifacts, the subjective scores of 90-200 keV group were significantly higher than those of conventional image group (χ²=207.2, 240.1, 260.5, 281.6, 302.0, 322.4, 322.6; P<0.05). The consistency of subjective scores between two radiologists was high (κ=0.85).

Single-energy images reconstructed based on spectral CT can effectively reduce the intraluminal artifacts of stents after TIPS, and improve the diagnostic confidence and image quality. Images of 120 keV are the optimal single-energy images.