双能量CT虚拟铁浓度成像技术在肝铁过载中的应用研究

Application of Dual-Energy CT Virtual Iron Concentration Imaging Technology in Liver Iron Overload

目的:评估第三代双源CT双能量技术虚拟铁浓度(VIC)成像应用于肝铁定量及分级的可行性和准确性。方法:腹腔内注射不同浓度的右旋糖酐铁构建肝铁过载大鼠模型,造模完成后行CT扫描和VIC图像重建,解剖取肝脏组织,用电感耦合等离子体光谱仪(ICP)定量肝铁浓度(LIC)并作为金标准。由2名放射科医师在VIC图像上勾画ROI并测量CT值,结果的可靠性用组内相关系数分析。变量间的相关性均用Spearman相关性分析评估,采用Bland-Altman比较两种方法定量LIC的一致性。根据临床铁过载治疗的分级阅值,结合ROC曲线和约登指数确定肝铁分级的最佳截断值,灵敏度和特异度,并用AUC评估分级效能。结果:ICP-LIC范围为0.32~39.21mg/g,CT值测量结果可靠(Kappa值=-0.001,P=0.807)。给药剂量和CT-VIC均与ICP-LIC有很高的相关性(ρ分别为0.91和0.98,P均小于0.0001)。VIC成像与ICP法对肝铁定量的结果一致(H0平均值=0,P=0.9859)。肝铁过载分级(1.8,3.2,7.0和15.0mg/g)的最佳截断值分别为37.65、41.45.47.05和73.40HU,各分级的AUC均超过0.95,灵敏度与特异度分别为83.3%和100%、90.9%和100%、97.2%和93.5%、100%和97.4%。结论:第三代双源CT双能量技术虚拟铁浓度成像能够精准定量肝铁浓度,同时还可对肝铁过载程度准确分级,诊断的灵敏度和特异度高。

Purpose:To evaluate the feasibility and accuracy of virtual iron concentration(VIC)imaging using the third-generation dual source computed tomography(DSCT)in quantification and grading of liver iron overload.Methods:Liver iron overload rat model was established by intraperitoneal injection of different dosage iron dextran.VIC imaging was reconstruction after CT scanning and part of the liver was removed for liver iron concentration(LIC)quantificated by inductively-coupled plasma spectrometer(ICP)as golden standard.CT values of ROIs were measured by 2 radiologists independently,and intraclass correlation coefficient(ICC)was used to analysis the reliability of measurement results.The correlations among the variables were evaluated by Spearman correlation analysis.Bland-Altman was used to compare the consistency of VIC imaging and ICP in LIC quantification.According to the clinical treatment of iron overload threshold,ROC combined with Youden index were used to determine the optimal cutoff values of grading liver iron overload,and the sensitivity and specificity were calculated.AUC was used to evaluate the grading diagnosis efficiency.Results:The range of ICP-LIC was 0.32-39.2lmg/g.The measured CT values were in good consistence(Kappa value=-0.001,P=0.807).Dosage was highly correlated with ICP-LIC(ρ=0.91),the same as CT-VIC(ρ=0.98,P<0.01).The results of VIC imaging were in consistent with that of 1CP for L1C quantification(HO:Average=0,P=0.9859).The optimal cutoff values of grading liver iron overload(1.8,3.2,7.0 and 15.0 mg/g,respectively)were 37.65HU,41.45HU,47.05HU and 73.40HU,respectively.The AUC of each grade was greater than 0.95,the sensitivity and specificity were 83.3%and 100%,90.9%and 100%,97.2%and 93.5%,100%and 97.4%,respectively.Conclusion:The third-generation DSCT VIC imaging can be used to accurately quantify LIC,and is with strong grading ability with high sensitivity and specificity.