Application Of IVIM-DWI And DKI In Chemoradiotherapy Of Nasopharyngeal Carcinoma

Purpose:To understand the application value of IVIM-DWI and DKI in chemoradioth-erapy efficacy evaluation of nasopharyngeal carcinoma,and to lay a foundation for clinical promotion.Materials and methods:There were 29 cases of nasopharyngeal carcinoma confirmed by pathology.During chemoradiotherapy,all subjects underwent MRI examination including IVIM-DWI,DKI and routine MRI scan sequence.The examination time points were before treatment,the completion of 1/3 radiation dose,the completion of 2/3 radiation dose and the end of radiotherapy.According to Resist1.1 Standard,patients with nasopharyngeal carcinoma were divided into respond group?RG?and non-respond group?NRG?after treatmentIVIM-DWI and DKI parameters?D,f,D*,MD,MK?were measured by professional software and analyzed statistically.Pearson Correlation Test was used to analyze the correlation between the parameters.Anova was used to observe the dynamic changes of parameters during treatment.IVIM-DWI and DKI parameters and their changes between different treatment groups were analyzed by Independent T Test.ROC curve was used to analyze the ability of each parameter to predict the effectiveness of chemoradiotherapy for nasopharyngeal carcinoma.Results:1 Grouping results:After the end of chemoradiotherapy,patients with nasopharyngeal carcinoma were divided into the respond group?n=20?and the non-respond group?n=9?.2 Variation trends of IVIM-DWI and DKI parameters:With the progress of chemoradiotherapy,D value and MD value presented an upward trend,MK value gradually decreased,f value went up and then went down,and D*value showed no significant change.3 Comparison of parameters between the respond group and the non-respondgroup:The respond group's baseline D value was significantly lower than that of the non-respond group(0.6±0.16×10^-3mm²/s vs 0.73±0.13×10^-3mm²/s,p=0.049),and the corresponding baseline MK value of effective group was significantly higher than that of the poor-effective group?0.95±0.11 vs 0.8±0.14,p=0.006?.During the period of chemoradiotherapy,the changes of D,MD and MK values in the respond group at the third and fourth examinations were significantly greater than those in the non-respond group?p<0.05?.At the end of chemoradiotherapy,compared with the non-respond group,the respond group had higher D₄ value,lower f₄ value and lower MK₄ value(D₄:1.38±0.26×10^-3mm²/s vs 1.08±0.24×10^-3mm²/s,p=0.009;f₄:17.18±5.16%vs24.04±7.0%,p=0.006;MK₄:0.48±0.09 vs 0.59±0.13,p=0.01).4 Efficacy prediction of IVIM-DWI and DKI parameters:MK₁ and?MK₃ have good prediction ability.The MK₁ threshold was 0.77,with a sensitivity of 90%,a specificity of 56%,and an AUC value of 0.8.?MK₃ has the strongest predictive power,with an AUC of 0.956,threshold of-0.265,sensitivity of90%,and specificity of 89%.Conclusion:IVIM-DWI and DKI can noninvasively monitor the dynamic changes of microstructure in the process of nasopharyngeal carcinoma chemoradiotherapy,which is of high value in the early evaluation of tumor efficacy.