Abstract: Background　In the evaluation of the efficacy of transarterial chemoembolization （TACE） for hepatocellular carcinoma（HCC），conventional CT examination is prone to producing heavy beam-hardening artifacts in images due to use of iodized oil，but dual-energy CT with advanced virtual monoenergetic reconstruction technique can reduce the beam-hardening artifacts，which is of great significance in accurately evaluating TACE efficacy.Objective　To analyze the clinical value of advanced virtual monoenergetic reconstruction technique in dual-energy CT for evaluating TACE efficacy in HCC to explore the effect of this technique in reducing iodized oil-induced artifacts in images.Methods　The clinical data of 31 patients with HCC who underwent dual-source dual-energy CT examination after TACE in Xianning Central Hospital from September 2015 to October 2017 were retrospectively analyzed.The third generation Flash dual-source CT dual-energy scan was performed.Each patient's linear blending images（M=0.5） and 16 groups of monoenergetic images reconstructed in 10-keV intervals（40，50，60，70，80，90，100，110，120，130，140，150，160，170，180，and 190 keV） were obtained，respectively.CT images influenced most by iodine deposition were selected in which iodized oil-induced artifacts and the normal areas were measured.The objective indices，including image artifact indices，contrast to noise ratio（CNR），the beam-hardening artifacts，image noise，contour of iodized oil deposition，and comprehensive subjective score were compared between the linear blending images and keV images.After comparative analysis，the best monoenergetic keV images with beam-hardening artifacts removed were identified.Results　Iodized oil-induced beam-hardening artifacts：In virtual monoenergetic images，beam-hardening artifacts from iodized oil tended to decrease with the increase of energy levels.Image noise：With the increase of energy，the image noise in the 40-80 keV images decreased gradually，and then increased slowly.Contour of iodized oil deposition：Iodized oil deposits were clearly displayed on 60-80 keV images.There was no significant difference between linear blending images and 70-100 keV images in comprehensive subjective score（P>0.05）.There was no significant difference between linear blending images and 40-50 keV images in artifact indices（P>0.05）.And there was no significant difference between linear blending images and 120-190 keV images in CNR（P>0.05）.Statistical analysis with comprehensive indices indicated that 70 keV and 80 keV were the optimal monoenergetic parameters for dual-energy CT scan with advanced virtual monoenergetic reconstruction technique，which could ensure that the images have appropriate CNR，with reduced beam-hardening artifacts，ideal iodine's contour，and AI and overall quality similar to those of linear blending images.Conclusion　In evaluating TACE efficacy in HCC，using advanced virtual monoenergetic reconstruction technique in dual-energy CT scan can reduce the incidence of iodized oil-induced beam-hardening artifacts in images.Under the conditions of 70 keV and 80 keV，the quality of images are best，the CNR of the images can be guaranteed，beam-hardening artifacts can be reduced，iodine's contour can be displayed well，AI and overall quality similar to those of linear blending images can be achieved.

Key words: Liver neoplasms；Tomography, spiral computed；Dual-energy CT；Beam-hardening artifact；Transcatheter hepatic arterial Chemoembolization；Monoenergetic plus images

摘要： 背景　肝癌经导管动脉化疗栓塞（TACE）术后常规CT检查中碘油易产生较重的线束硬化伪影，双源CT虚拟新单能量重建技术可以减小碘油线束硬化伪影，对正确评价肝癌TACE术后疗效具有重要的临床意义。目的　探讨双源CT新虚拟单能量重建技术在肝癌TACE术后的临床应用价值，探讨该技术在降低碘油沉积灶伪影方面的效果。方法　回顾性分析2015年9月—2017年10月在咸宁市中心医院TACE术后完成双源双能量CT扫描的31例肝癌患者的临床资料。对肝癌TACE术后患者进行双源CT双能量扫描，并以10 keV为间隔重组16组（40、50、60、70、80、90、100、110、120、130、140、150、160、170、180、190 keV）新单能量重建图像，在线性融合图像（M=0.5）及16组新单能量重建图像上，选择碘油沉积最明显的层面，测量碘油硬化伪影区及同层面正常肝实质CT值。通过比较线性融合图像和各组新单能重建图像的客观指标伪影指数（AI）及对比噪声比（CNR），从图像硬化伪影、图像噪声及碘油形态显示情况三个方面进行观察，并对整体图像质量进行综合主观评分，获得单能量去碘油硬化伪影最佳的图像keV。结果　碘油硬化伪影：在虚拟单能量图像中碘油硬化伪影随能级升高呈降低趋势。图像噪声：随着能级的升高，图像噪声在40~80 keV图像上逐渐下降，随后呈缓慢上升趋势。碘油形态显示：以60~80 keV新单能重建图像上碘油沉积灶显示较为清晰。线性融合图像与70~100 keV新单能量重建图像质量综合主观评分比较，线性融合图像与60~190 keV新单能量重建图像AI值比较，线性融合图像与120~190 keV新单能量重建图像CNR比较，差异无统计学意义（P>0.05）。70、80 keV新单能量重建图像可在保证图像CNR的同时有效减少线束硬化伪影，碘油形态显示满意，AI值与线性融合组相近，与线性融合图像的图像质量相似。结论　双源CT新虚拟单能量重建技术可以减少肝癌TACE术后碘油沉积的硬化伪影，以70 keV及80 keV的虚拟单能量图像重建效果最佳，可在保证图像CNR的同时有效减少线束硬化伪影，碘油形态显示满意，AI与线性融合组相近，与线性融合的图像质量相似。

关键词: 肝肿瘤；体层摄影术, 螺旋计算机；双能量CT；线束硬化伪影；经导管动脉化疗栓塞；虚拟新单能量图像