The Value Of ¹⁸F-FDG PET/MR-IVIM In Pre-Treatment Diagnosing Lymph Node Metastasis Of Pelvic Malignant Tumors

Objective:To evaluate the value of ¹⁸F-FDG PET/MR to diagnose lymphatic metastasis in pelvic malignancies and diagnostic accuracy in PET and IVIM sequence.Furthermore,we research the intrinsic relationship between lymph node metabolic and diffusion parameters in order to explore the microcosmic imaging features of metastatic lymph nodes.Methods:From May 1,2017 to August 31,2018,patients with pelvic malignant tumors who underwent PET/MR examination,lymph node dissection and/or regular radiotherapy and chemotherapy in Shengjing Hospital affiliated to China Medical University were collected.The diagnosis efficacy of PET/MR in lymph node metastasis was evaluated.The differences between lymph nodes with and without metastasis were compared.The correlation between diffusion parameters and metabolic parameters was analyzed.Results:116 patients with pelvic malignant tumor were included in the study.The sensitivity,specificity and accuracy of PET/MR in diagnosing lymphatic metastasis were 96.88%?31/32?,94.04%?79/84?and 94.83%?110/116?.In the PET/MR positive lymph nodes in accordance with the study criteria,SUV_max,SUV_mean,MTV,TLG,D and f had significant difference between the metastatic and non-metastatic groups?both P<0.05?.The results of correlation analysis showed that the correlation coefficient between TLG and f was-0.526?P<0.05?,but there was no significant correlation between other metabolic parameters and diffusion parameters.Conclusion:¹⁸F-FDG PET/MR is effective in the diagnosing lymph node metastasis of pelvic malignant tumor.The characteristics of hypermetabolism,limited diffusion and decreased perfusion were found in metastatic lymph nodes.The metabolic parameters?TLG?were negatively correlated with perfusion fraction f,which further indicated the microcosmic imaging changes in metastatic lymph nodes.