实性肺结节低剂量CT影像组学图像质量控制的体模研究

目的探讨影像组学在低剂量CT扫描条件下实性肺结节CT图像质量控制中的应用价值。方法使用CT750 HD CT分别在不同管电压及不同管电流下对胸部肺结节人体仿真模型进行扫描,记录不同扫描条件下的容积CT剂量指数(CTDIvol),测量并计算图像中结节的信噪比(SNR)和对比噪声比(CNR),分析辐射剂量、噪声与管电压管电流变化的规律,将所有扫描数据通过影像组学分析软件对实性结节的全部特征进行提取,使用R语言统计学软件对提取的特征参数进行主成分分析,选取主成分中对图像质量贡献较大的特征进行分析。对确定的重要特征参数进行单因素方差分析,揭示不同管电压下特征参数的差异,再进一步通过事后检验对不同管电压组之间进行两两比较,找出组间差异。结果辐射剂量在研究的范围内随管电压、管电流的增加而线性增加。肺结节的SNR和CNR总体变化趋势虽然与管电压及管电流的变化呈线性关系,但在低剂量下没有明确的变化趋势阈值存在,无法准确评价低辐射下图像质量。影像组学提取的所有特征参数中均质性、体素值总和及Haralick相关性是3个主要成分,其方差累计的贡献率为89.2%,且特征值均>1。特征参数均质性曲线显示出其变化趋势与管电压及管电流变化成相关性,且稳定性和一致性较好。均质性单因素方差分析结果显示在管电压140及120 kVp时,两组间的均质性值的变化差异无统计学意义(P=0.117),而在其他管电压间均质性值变化差异均有统计学意义(P<0.001)。当管电压在100 kVp、管电流≥60 mA时或管电压在80 kVp、管电流≥90 mA时,均质性无明显变化,可以得到满意的图像质量。结论影像组学分析方法可以有效定量化地评价和控制低辐射剂量下实性肺结节CT图像质量。

Phantom study in the quality control of low dose solid pulmonary nodule CT based on radiomics analysis

Objective To investigate the value of radiomics in image quality control with low-dose CT examination of solid pulmonary nodules.Methods Images were acquired on CT750 HD scanner,and chest pulmonary nodules phantom were scanned at different tube voltage and tube current.The radiation dose CTDIvol under different scanning conditions were recorded,as well as CNR and SNR of each scanning sequence.The variation of radiation dose,noise,tube voltage and tube current were analyzed.All data were analyzed by radiomics analysis software.R language statistics software was adopted to analyze the extracted features by principal component analysis(PCA),and the characteristic parameters with the largest contribution rate to image quality were selected for analysis.One-way ANOVA was used to analyze all the important characteristic parameters to reveal the difference of characteristic parameters under different tube voltages.Finally,the post-test method was used to find out the differences among different tube voltage groups.Results Radiation dose rised linearly with the increase of tube current and tube voltage.Although the overall change trend of SNR and CNR in pulmonary nodules was linearly related to the change of tube voltage and tube current,there was no clear change trend threshold at low dose,which could not accurately evaluate the image quality under low radiation.Both CNR and SNR cannot evaluate the image quality effectively,and have no practiced value for optimizing the low dose scanning parameters.There main components including Uniformity,Voxel Value Sum,and Haralick Correlation extracted by radiomics analysis software were proved to play a critical role in image quality control.The cumulative contribution rate of variance was 89.20%and the eigen values were greater than 1.Uniformity curve of characteristic parameter showed that the trend of change was correlated with the change of tube voltage and tube current,and the stability and consistency were good.Uniformity one-way ANOVA analysis showed that when the tube voltage reduced from 140 to 120 kVp,there was no difference(P=0.117)in the uniformity,while from 120 to 80 kVp,significant differences revealed(P<0.001).Considering tube current,no significant variation was observed in uniformity when current was greater than 90 mA,which indicated that tube current of 90 mA could lead to better image quality.Conclusion Radiomics analysis can effectively evaluate and control the CT image quality of low dose solid pulmonary nodules.