The Combined Predictive Value Of PET And MR-IVIM For The Early Treatment Response And Recurrence Of Locally Advanced Cervical Cancer After Concurrent Chemoradiotherapy

Objective:To assess the value of ¹⁸F-fluorodeoxyglucose positron emission tomography(¹⁸F-FDG PET)and intravoxel incoherent motion magnetic resonance imaging （MR-IVIM）parameters for predicting tumor recurrence in patients with locally advanced cervical cancer（LACC）using a hybrid PET/MR scanner.Material and Methods:Fifty-one patients with LACC scheduled for concurrent chemoradiotherapy（CCRT）underwent pelvic PET/MR scans with an IVIM sequence（PET/MR-IVIM）at two time-points（pretreatment[pre]and at the end of the fourth week[week 4]during CCRT[mid]）.Pre-and mid-PET parameters(SUV_max,MTV,TLG)and IVIM parameters（D,F,D*）and IVIM percentage changes（Δ%D,Δ%F,Δ%D*） were compared according to tumor early shrinkage rate and recurrence.The combined predictive value（CPV）was calculated based on the optimal screened metabolic, diffusion and perfusion parameters.The Kaplan-Meier method and Cox regression analysis were performed to determine relapse-free survival.Results:Thirty-two patients were classified into the good response（GR）group with tumor early shrinkage rate≥50%at week 4,and 19 patients were categorized into the poor response（PR）group with tumor early shrinkage rate<50%.Δ%D（p=0.005）andΔ%F（p=0.010）were significantly higher in the GR group than in the PR group.The Kaplan-Meier method indicated that relapse-free survival was significantly different for suspicious lymph node metastasis（p=0.0002）,tumor early shrinkage rate（p=0.0281）,pre-MTV（p=0.0145）,pre-TLG（p=0.0018）,mid-TLG（p=0.0004）,Δ%D（p=0.0039）and CPV（p<0.0001）.In the Cox regression analysis,suspicious lymph node metastasis（hazard ratio[HR],2.86;p=0.029）and CPV（HR,3.30;p=0.030）were the independent prognostic factors.Conclusion:The combined predictive value,which combining pretreatment PET metabolic parameters（i.e.,TLG）and the percentage changes in IVIM parameters（i.e.,D and F）between pretreatment and week 4 of CCRT,provides great potential for predicting tumor recurrence in patients with LACC who are undergoing treatment with CCRT.