Clinical Value Of Bimodal Molecular Imaging Parameters In NK/T Cell Lymphoma

PURPOSE:To evaluate the prognostic value of positron emission tomography-computed tomography(PET/CT)and magnetic resonance imaging(MR)in NK/T-cell lymphoma,and to use hybrid PET/MR in this type of lymphoma.A preliminary study was conducted on the diagnostic staging value.Materials and Methods:Part I:Retrospective analysis of 27 patients with NK/T-cell lymphoma diagnosed by the pathology of Ruijin Hospital Shanghai Jiaotong University School of Medicine from March 2014 to January 2018.These patients all underwent baseline PET/CT and local MR examination before treatment,and the interval between the two examinations was no more than two weeks.All of these patients received a chemotherapy regimen containing enantiamase and received both radiotherapy during chemotherapy.The maximum standardize uptake value(SUVmax),metabolic tumor volume(MTV),total lesion glycolysis(TLG),and local tumor invasion(LTI)of local MR examination were statistically analyzed for all PET/CT baseline examination patients.Kaplan-Meier survival curves and COX regression analysis were performed with progression-free survival(PFS)and overall survival time(OS)as indicators.Part II:Retrospective analysis of 9 patients with NK/T-cell lymphoma diagnosed by Ruijin Hospital Shanghai Jiao Tong University School of Medicine from 2018 to May.All patients underwent baseline PET/CT and PET/MR examinations.The inspection interval does not exceed 0.5 hours.The nasopharynx and head and neck regions of these 9 patients were divided into 63 regions(nasal cavity,nasopharynx,oral and oral cavity,paranasal sinus,subcutaneous soft tissue,bone and cervical lymph nodes),and the lesions were counted in each region.RESULTS:Kaplan-Meier survival curves showed that MTV and TLG were associated with patient outcomes.According to the ROC curve and the area under the curve,the best MTV(16.97,sensitivity 100%,specificity 77.3%,area under the curve(AUC):0.891)and TLG(7.47�10~4,sensitivity 100%,specificity 54.5%,were calculated.AUC:0.727)Threshold,survival curves plotted after high-risk and low-risk groups showed that MTV and TLG were predictive of progression-free survival(P=0.013 and 0.029,respectively).SUVmax(8.05,sensitivity 80%,specificity 27.3%,AUC:0.309)and LTI could not predict progression-free survival(P=0.661 and 0.217,respectively).However,the four imaging parameters were unable to predict the overall survival time(SUVmax,P=0.293,MTV,P=0.198,TLG,P=0.108,LTI,P=0.254).Multivariate outcome analysis showed that only MTV was an independent factor affecting the prognosis of patients with NK/T-cell lymphoma(P=0.044).Patients in the high MTV group had a significantly higher risk of recurrence or death than those in the low MTV group,HR=9.55(95%CI:1.06-85.84).Among the 9 patients who underwent PET/CT and PET/MR in the second part of the study,PET/MR showed superiority to PET/CT in lesion diagnosis(100%vs.97.5%),PET/CT misdiagnosed a case of nasopharyngeal lesions,and the accuracy of PET/MR is better than PET/CT(100%vs.98.4%).Conclusion:PET/CT parameters MTV and TLG have obvious advantages in prognosis,while LTI can not effectively assess prognosis.In addition,PET/MR examination may be superior to PET/CT in terms of specificity and accuracy,and superior to PET/CT in areas with complex anatomical structures and in judging small lymph node involvement.