Purpose To evaluate the reproducibility of radiomics features by repeating computed tomographic (CT) scans in rectal cancer. To choose stable radiomics features for rectal cancer. Results Volume normalized features are much more reproducible than unnormalized features. The average value of all slices is the most reproducible feature type in rectal cancer. Different filters have little effect for the reproducibility of radiomics features. For the average type features, 496 out of 775 features showed high reproducibility (ICC ≥ 0.8), 225 out of 775 features showed medium reproducibility (0.8 > ICC ≥ 0.5) and 54 out of 775 features showed low reproducibility (ICC < 0.5). Methods 40 rectal cancer patients with stage II were enrolled in this study, each of whom underwent two CT scans within average 8.7 days. 775 radiomics features were defined in this study. For each features, five different values (value from the largest slice, maximum value, minimum value, average value of all slices and value from superposed intermediate matrix) were extracted. Meanwhile a LOG filter with different parameters was applied to these images to find stable filter value. Concordance correlation coefficients (CCC) and inter-class correlation coefficients (ICC) of two CT scans were calculated to assess the reproducibility, based on original features and volume normalized features. Conclusions Features are recommended to be normalized to volume in radiomics analysis. The average type radiomics features are the most stable features in rectal cancer. Further analysis of these features of rectal cancer can be warranted for treatment monitoring and prognosis prediction.

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直肠癌放射线学研究中重复CT的重现性

目的通过在直肠癌中重复进行计算机断层扫描（CT）扫描来评估放射性组学特征的可重复性。为直肠癌选择稳定的放射学特征。结果体积归一化特征比非归一化特征具有更高的可复制性。所有切片的平均值是直肠癌中最可复制的特征类型。不同的过滤器对放射性组学特征的再现性影响很小。对于普通类型特征，在775个特征中有496个具有高可重复性（ICC≥0.8），在775个特征中有225个具有中等可重现性（0.8> ICC≥0.5），在775个特征中有54个具有低可重复性（ICC <0.5）。方法本研究纳入40例II期直肠癌患者，每人平均在8.7天内进行了两次CT扫描。在这项研究中定义了775个放射学特征。对于每个特征，提取五个不同的值（最大切片的值，最大值，最小值，所有切片的平均值和叠加的中间矩阵的值）。同时，将具有不同参数的LOG滤镜应用于这些图像，以找到稳定的滤镜值。基于原始特征和体积归一化特征，计算了两次CT扫描的一致性相关系数（CCC）和类间相关系数（ICC）以评估可重复性。结论建议在放射组学分析中将功能标准化为体积。平均类型的放射学特征是直肠癌中最稳定的特征。直肠癌的这些特征的进一步分析可以保证用于治疗监测和预后预测。