能谱CT虚拟平扫在儿童肝肿瘤中的应用价值

Study on children with liver tumors by spectral CT virtual non-contrast images

目的:通过能谱CT虚拟平扫水基(WB)图、物质压碘(MSI)图与真实平扫(TNC)对儿童肝肿瘤进行定性和定量研究,探讨虚拟平扫替代真实平扫的可行性。方法:连续性搜集我院30例肝肿瘤患儿,所有患儿均行CT平扫、动脉期、门脉期和实质期扫描。将门脉能谱GSI数据导入后处理工作站生成虚拟平扫WB图和MSI图,对TNC、WB和MSI三组图像进行5分制主观评分和病灶检出能力比较。测量TNC和WB各个部位的CT值和图像背景噪声,计算肝实质和肝肿瘤的信噪比(SNR),比较TNC、WB和MSI三组图像的对比噪声比(CNR)。采用相关样本的符号秩和检验比较TNC与MSI的相关参数,对TNC、MSI、WB图像的CNR值和主观评分分别进行方差分析和Kruskal-Wallis H检验。结果:MSI的SD值、肝肿瘤和腹主动脉的CT值、肝实质和肝肿瘤的SNR值均高于TNC,而肝实质的CT值低于TNC,差异均有统计学意义(P<0.05);三组图像对病灶的检出能力差异无统计学意义(P>0.05)。WB图的CNR(4.74±0.32)高于TNC图(3.07±0.27)和MSI图(3.41±0.28),而MSI和TNC的主观评分均高于WB,差异均有统计学意义(P<0.05);MSI与TNC之间的CNR、主观评分差异均无统计学意义(P>0.05)。能谱三期扫描的有效辐射剂量较常规四期扫描下降约22%。结论:儿童肝门脉期能谱CT虚拟平扫可以提供较好的图像质量和诊断信息,替代TNC可降低22%的辐射剂量。

Objective:In order to explore the feasibility of virtual plain CT instead of real plain CT,we used energy spectrum CT virtual plain CT water-based(WB)image,material iodized iodine(MSI)image and real plain CT(TNC)image to study the qualitative and quantitative characteristics of pediatric liver tumors.Methods:There were 30 children with liver tumors in our hospital performed CT in non-contrast,artery,portal vein and parenchymal phase.The spectral GSI data were transmitted into post-processing station AW4.7 to generate WB images and MSI images.The TNC,WB and MSI images were scored subjectively on 5 points and the sensitivity of lesion detection was evaluated.The CT values and image background noise of TNC and WB were measured,and the signal-to-noise ratio(SNR)values of liver parenchyma and liver tumors were calculated.Meanwhile,the contrast noise ratio(CNR)values of TNC,WB and MSI images were compared.Wilcoxon rank sum test was used to compare the parameters of TNC and MSI.The analysis of variance and Kruskal-Wallis H test were carried out respectively on the CNR values and subjective scores.Results:SD value of MSI,CT value of liver tumor and abdominal aorta,SNR value of liver parenchyma and liver tumor were all higher than TNC,while CT value of liver parenchyma was lower than TNC.There was no significant difference in the sensitivity of the three groups in detecting lesions(P>0.05).The CNR of WB(4.74±0.32)was higher than TNC(3.07±0.27)and MSI(3.41±0.28),while the subjective scores of MSI and TNC were higher than those of WB(P<0.05).There was no significant difference in CNR and subjective scores between MSI and TNC(P>0.05).The effective radiation dose ED of energy spectrum three-phase scanning was about 22%lower than that of conventional phase IV scanning.Conclusions:Spectral CT virtual non-contrast images of hepatic portal phase in children can provide comparable image quality and diagnostic information,which replace TNC can reduce radiation dose by 22%.