Application Of MRI-IVIM And ¹⁸F-FDG PET/CT Parameters In Predicting The Curative Effect Of Concurrent Chemoradiotherapy For Locally Advanced Cervical Cancer

Objective:To study the value of multi-model quantitative parameters of intravoxel incoherent motion magnetic resonance imaging（MRI-IVIM）and metabolic parameters of 18-fluorodeoxyglucose positron emission tomography(^{1 8}F-FDGPET/CT)in predicting the short-term efficacy of concurrent chemoradiotherapy（CCRT）for locally advanced cervical cancer（LACC）.Methods:Prospective analysis of patients with cervical cancer confirmed by biopsy in Cancer Hospital Affiliated to Guangxi Medical University from October 2019 to November 2020.All patients underwent MRI-IVIM and 18F-FDGPET/CT examination one week before treatment.Patients with cervical cancer who were included in CCRT were given routine pelvic MRI scan one month after CCRT.After scanning,all the MRI original images were transmitted to GEAdvantage Workstation（AW4.6）,and the tumor length and diameter were measured,and the MRI-IVIM model parameters were measured and recorded:monoexponential model:diffusion coefficient（ADC）,mono-index model:pure water molecular diffusion coefficient（D-mono）,pseudo-diffusion coefficient（D^*-mono）,perfusion fraction（f-mono）,bi-index mode:pure water molecular diffusion coefficient（D-bi）,pseudo-diffusion coefficient（D^*-bi）,perfusion fraction（f-bi）,stretched-exponential mode:diffusion distribution coefficient（DDC）,water molecular diffusion heterogeneity index（α）.Transfer PET and CT images directly to Xeleris workstation for automatic fusion,and then measure and record the maximum standardized uptake value（SUVmax）,average standardized uptake value（SUVmean）and minimum standardized uptake value（SUVmin）of m etabolic parameters.According to the evaluation standard of curative effect of solid tumor（RECIST1.1）,according to whether the patients had residual tumor after treatment,the patients were divided into the incomplete response group（NCR）and the complete response group（CR）.T-test and Mann-Whitney U test were used to compare the differences of parameters between CR group and NCR group,and to analyze the relationship between each parameter and curative effect.Spearman correlation test was used to analyze the relationship between various parameters and tumor length and diameter and parameters.The receiver operating characteristic curve（ROC）was drawn for meaningful parameters,and the corresponding area under the curve（AUC）,optimal threshold,specif icity and sensitivity were calculated.To compare the predictive short-term efficacy of each parameter on the efficacy of CCRT in patients with LACC.Results:1.Finally,36 patients were included in the study.All patients were squamous cell carcinoma,in cluding 21 cases in CR group and 15 cases in NCR group.The results of this study showed that age,squamous cell carcinoma antigen（SCC-Ag）,carbohydrate antigen 125（CA125）,hemoglobin（Hb）,Body-mass index（BMI）,tumor length and diameter,FIGO stage,differentiation degree,lymph node metastasis and menopause were not significantly different between CR group and NCR group（P>0.05）.2.The ADC,D-mono,DDC values in MRI-IVIM multi-model parameters were higher in RT group than in CR group（P=0.019,0.001,0.009）,but there was no significant difference in D*-mono,f-mono,D-bi,f-bi,αvalues between CR group and NCR group（P>0.05）3.^{1 8}F-FDG PET/CT parameters SUVmax,SUVmean and SUVmin had no significant difference between CR group and NCR group（P>0.05）.4.ADC values were positively correlated with D-mono and DDC values（r=0.696,0.756,P<0.05）.There is a positive correlation between D-mono value and DDC value（r=0.678,P<0.05）.SUVmax was highly correlated with SUVmean（r=0.967,P<0.05）.5.The AUC of ADC,D-mono and DDC in predicting the curative effect of CRRT in patients with LACC were 0.732,0.830 and 0.759,and the corresponding thresholds were 1.12×10-3mm2/s,0.85×10-3mm2/s and 1.02×10-3mm2/s,respectively,with sensitivity and specificity were60%,80%,66.7%,and 76.2%,81%,81%.Conclusions:The diffusion-related parameters ADC,D-mono and DDC of MRI-IVIM multi-model can predict the CCRT short-term efficacy of LACC,and the second-order single exponential model parameter D-mono has the best prediction performance.In this study,SUV parameters of 18F-FDGPET/CT before treatment have no value in predicting the short-term curative effect of CCRT in patients with LACC.