Application Of MR Functional Imaging In The Evaluation Of Neoadjuvant Therapy For Locally Advanced Gastric Cancer

Objective:To explore the clinical application value of magnetic resonance imaging in evaluating the efficacy of neoadjuvant chemoradiotherapy for locally advanced gastric cancer.Methods:Patients with locally advanced gastric cancer who were admitted to the our Hospital from August 2017 to December 2018 were prospectively collected.Conventional T1WI,T2WI,DWI and DCE-MRI sequence scans were performed before and after radiotherapy and chemotherapy.The thickest diameters Dbefore and Dafter before and after tumor treatment were measured,and the difference?D was calculated.According to the RECIST1.1 standard,the efficacy of gastric cancer chemotherapy and radiotherapy was evaluated.The quantitative parameters of gastric cancer Ktans,Kep and ve were obtained by Siemens?MAGNETOM skyra 3.0T?post-processing work software Tissues 4D and the change values?Ktans,?Kep and?Ve were calculated.The ADC value of the tumor was measured on the ADC map,and the change value?ADC before and after treatment was calculated.Postoperative TRG was divided into 0,1,2,3,grades.Define TRG?0,1,2?as the active group and TRG3 as the invalid group.Spearson test was used to analyze the correlation between the parameters of the lesions before and after chemotherapy and the tumor regression scale.The independent sample t test or Mann-Whitney U test was used to analyze the difference of?Ktans,?Kep,?Ve and?ADC values before and after treatment.The tester's work characteristic ROC curve is used to further analyze the optimal diagnostic performance value.The statistical differences between the baseline parameters between the two groups were compared.P<0.05 was considered statistically significant.Results:There was a negative correlation between?Ktrans and?Kep and tumor regression scale?rho=-0.554,P=0.009;rho=-599,P=0.004?.There is a positive correlation between?ADC and TRG?rho=0.603,P=0.005?.The changes of Ktrans and ADC in the effective group were higher than those in the ineffective group?P<0.05?.Using the ROC curve,the AUC was 0.754.When?Ktrans was greater than 0.0075 min^-1,the diagnostic accuracy of NACR for gastric cancer was estimated to be 80%,the sensitivity was 92.9%,and the specificity was 55.6%.The ROC curve was performed on?ADC,and the AUC was 0.857.When the absolute difference of?ADC was greater than0.406×10^-3mm²/s,the accuracy of NACR prediction for gastric cancer was76%,the sensitivity was 100%,and the specificity was 71.4%.Conclusion:The magnetic resonance functional imaging DCE-MRI before and after treatment Ktrans'change value?Ktrans and DWI imaging ADC change value?ADC has a certain clinical value for the evaluation of therapeutic response to advanced gastric cancer after neoadjuvant chemoradiotherapy.