Stability Of CT Radiomic Features Extracted From Pulmonary Nodules

PART ⅠInfluence of CT acquisition and reconstruction parameters on the stability of radiomic features in pulmonary nodulesObjective To investigate the influence of CT reconstruction algorithm,radiation dose,and contrast agent on the stability of radiomic features in pulmonary nodules.Methods A total of 150 pulmonary nodules were prospectively selected from 96 patients.Six sequences with different parameters were obtained from the original image of the same patient.ITK-SNAP software was used to segment pulmonary nodules in different sequences.The radiomic features with good retest reliability were selected by intraclass correlation coefficient.The statistical software of R language was used to analyze the characteristic parameters.All the characteristic values of different sequences were matched and compared.The number of radiomic features changed by acquisition and reconstruction parameters was counted,respectively.The effects of varying acquisition and reconstruction parameters on the stability of radiomic features extracted from pulmonary nodules were compared.Results A total of 391 radiomic features were extracted from 150 cases of pulmonary nodules,and 320 features with an intraclass correlation coefficient greater than 0.75 were selected for further analysis.When the CT reconstruction algorithm,radiation dose,and contrast agent were changed,the range of changed features was 25.6%-38.4%,47.2%-63.1%,and 45.9%-54.1%,respectively.The number of changed radiomic features of pulmonary nodules caused by contrast agent was slightly more than that caused by radiation dose(P=0.08).The number of changed radiomic features of pulmonary nodules caused by radiation dose and contrast agent was higher than that caused by the reconstruction algorithm(P<0.01,P<0.01).Changing the three parameters of CT reconstruction algorithm,radiation dose,and contrast agent simultaneously made the change of radiomic features reach 66.6%(213/320).It included 26.7%(4/15)morphological features,95.0%(38/40)histogram features and 64.5%(171/265)texture features.The percentage of changing histogram features and changing texture features were higher than morphological features(P<0.01,P<0.01).When the radiation dose and contrast agent were changed,the number of changed radiomic features of pulmonary nodules obtained by the FBP algorithm was slightly less than 50%ASiR-V(P=0.67).Conclusions CT reconstruction algorithm,radiation dose,and contrast agent would affect the radiomic features extracted from pulmonary nodules.The influence of radiation dose and contrast agent on the stability of radiomic features is more significant than that of the reconstruction algorithm.Histogram and texture features are more easily affected by CT acquisition and reconstruction parameters than morphological features.When the radiation dose and contrast agent were changed simultaneously,the stability of the radiomic features obtained by the FBP reconstruction algorithm is slightly better than that obtained by the 50%ASiR-V algorithm.The influence of these parameters should be fully considered in the radiomics analysis.PART ⅡStability comparison of CT radiomic features in different consistency pulmonary nodulesObjective To compare the stability of radiomic features among pure ground-glass density,part-solid,and solid pulmonary nodules.Methods 50 pure ground-glass pulmonary nodules,50 part-solid pulmonary nodules,and 50 solid pulmonary nodules were prospectively selected.The original images of pulmonary nodules in the same patient were reconstructed,and six sequences with different parameters were obtained.The ITK-SNAP software was used to segment the pulmonary nodules with three different densities in different sequences.All the scanning data were extracted by A.K.(Analysis Kit)software of GE company.The radiomic features with good retest reliability were selected by the intraclass correlation coefficient.R language statistical software was used to analyze the characteristic parameters.All the feature values of different sequences were paired and compared.The number of radiomic features changed by the acquisition and reconstruction parameters was counted.The stability of radiomic features of three kinds of density pulmonary nodules was compared when CT acquisition and reconstruction parameters changed.Results(1)Influence of changing CT acquisition and reconstruction parameters on the stability of radiomic features extracted from different consistency pulmonary nodules ① For pure ground-glass pulmonary nodules,changing the reconstruction algorithm,radiation dose,and contrast agent parameters could influence the radiomic features in the range of 10.6%-40.3%,30.9%-46.3%,and 50.6%-64.1%,respectively.The features of pure ground-glass pulmonary nodules caused by the reconstruction algorithm were less than those caused by radiation dose(P<0.01).The features of pure ground-glass pulmonary nodules caused by radiation dose were less than those caused by contrast agent(P<0.01).The features of pure ground-glass density pulmonary nodules caused by the reconstruction algorithm were less than those caused by the contrast agent(P<0.01).② For part-solid pulmonary nodules,changing the reconstruction algorithm,radiation dose,and contrast agent parameters could influence the radiomic features in the range of 10.0%-14.1%,8.4%-23.8%,and 13.8%-17.5%,respectively.The features of part-solid pulmonary nodules caused by the reconstruction algorithm were less than those caused by radiation dose(P<0.01).The features of part-solid pulmonary nodules caused by contrast agent were less than those caused by radiation dose(P<0.01).The features of part-solid pulmonary nodules caused by the reconstruction algorithm were slightly more than those caused by the contrast agent(P=0.91).③For solid pulmonary nodules,changing the reconstruction algorithm,radiation dose,and contrast agent parameters could influence the radiomic features in the range of 34.7%-47.7%,20.0%-42.2%,and 41.3%-55.9%,respectively.The features of solid pulmonary nodules caused by the reconstruction algorithm were more than those caused by radiation dose(P<0.01).The features of solid pulmonary nodules caused by contrast agent were more than those caused by radiation dose(P<0.01).The features of solid pulmonary nodules caused by the reconstruction algorithm were slightly less than those caused by contrast agent(P=0.21).(2)The difference of stability of radiomic features between different consistency pulmonary nodules After sorting out the results of 12 sequences comparison,8 sequences comparison got consistent results.Those were,the changed radiomic feature extracted from pure ground-glass pulmonary nodules and solid pulmonary nodules had no significant difference(P>0.05).The changed radiomic feature extracted from part-solid pulmonary nodules was lower than that of pure ground-glass pulmonary nodules and solid pulmonary nodules(P<0.05).(3)Comparing radiomic features of three different consistency pulmonary nodules after changing parameters After subgroup analysis of 8 sequences comparison with consistent results,the main difference of stability among the three pulmonary nodules with different densities was texture features.When the parameters changed,the number of texture features of part-solid pulmonary nodules changed was lower than that of pure ground-glass pulmonary nodules and solid pulmonary nodules.Conclusion Reconstruction algorithm,radiation dose,and contrast agent have differenteffects on radiomic features of different consistency pulmonary nodules.For pure ground-glass pulmonary nodules,contrast agent has the most significant impact on the stability of radiomic features,followed by radiation dose.The reconstruction algorithm has the least impact on the stability of radiomic features.For part-solid pulmonary nodules,the effect of radiation dose on the stability of radiomic features is greater than that of the reconstruction algorithm and contrast medium.For solid pulmonary nodules,the influence of reconstruction algorithm and contrast agent on the stability of radiomic features is more significant than that of radiation dose.In changing the same parameters,the stability of the radiomic features of pure-ground glass density pulmonary nodules and solid pulmonary nodules is similar.The stability of the radiomic features of part-solid pulmonary nodules is better than that of pure ground-glass density pulmonary nodules and solid pulmonary nodules.Moreover,the difference in stability among the three different pulmonary nodules is mainly reflected in the texture features.In the follow-up radiomic studies of subsolid pulmonary nodules,pure ground-glass density pulmonary nodules and part-solid pulmonary nodules should be studied separately.