The Application Of Intravoxel Incoherent Motion Magnetic Resonance Imaging In Nasopharyngeal Carcinoma:Staging And Evaluating The Efficacy Of Chemoradiotherapy

Part ?:The application of intravoxel incoherent motion magnetic resonance imaging in the staging of nasopharyngeal carcinomaObjective:To explore the value of IVIM-MRI in the staging of nasopharyngeal carcinoma(NPC).Methods:This study prospectively included 63 patients with pathologically confirmed NPC.IVIM-MRI scans(9 b values:0,25,50,75,100,150,200,500,and 800 s/mm2)were performed on the enrolled patients.The ADC values were calculated by the mono-exponential model.The bi-exponential model were used to obtain the pseudodiffusion coefficient(D*),the pure diffusion coefficient(D),and the perfusion fraction(f),then comparing the differences of IVIM parameters between different stage groups and analyzing correlation between different parameters and different stages.Results:The D values and D*values of the high-stage group in the clinical stage were significantly lower than the low-stage group.The D values for the high-and low-stage groups were(0.617±0.080× 10-3 mm2/s,0.692±0.124× 10-3 mm2/s,P=0.021)respectively.The D*values for the high-and low-stage groups were(102.499±14.972× 10-3mm2/s,118.335±22.812×10-3mm2/s,P=0.002)respectively.The optimal thresholds of D and D*values for clinical stage were 0.642×10-3 mm2/s,106.618×10-3 mm2/s,and the AUC were 0.702,0.721.The D*values of the high-stage group in the N-staging were lower than the low-stage group.The D*values for the high-and low-stage groups were(100.647±13.798×10-3 mm2/s,114.037±21.193×10-3 mm2/s,P=0.004)respectively.The optimal threshold of the D*values for N-staging was 105.743×10-3 mm2/s and the AUC was 0.694.Conclusion:Some parameters of IVIM had good effects on clinical stage and N-staging of NPC.The D and D*values would be good parameters for the clinical stage of NPC.The D*value would also be a good parameter for N-staging of NPC.IVIM parameters could have a certain value for the staging of NPC.Part ?:The application of intravoxel incoherent motion magnetic resonance imaging in evaluating the efficacy of chemoradiotherapy of nasopharyngeal carcinomaObjective:To research the dynamic changes of the IVIM-MRI parameters during chemoradiotherapy of nasopharyngeal carcinoma(NPC),and to explore the value of IVIM-MRI in evaluating and predicting the efficacy of chemoradiotherapy in NPC.Methods:With the approval of the hospital's ethics committee and informed consent of patients,this study prospectively included 33 patients with NPC.The enrolled patients were confirmed as NPC by pathology(clinical stage:?-?A).Three IVIM-MRI scans(9 b values:0,25,50,75,100,150,200,500,and 800 s/mm2)were performed on the enrolled patients.Those patients underwent MRI at the time points of pretreatment(MRIpre),four weeks after the start of radiotherapy(MRI4th)and one month after the end of radiotherapy(MRIpost).The ADC value was calculated by the mono-exponential model.The bi-exponential model was used to obtain the pseudodiffusion coefficient(D*),the pure diffusion coefficient(D),and the perfusion fraction(f).The maximum area and IVIM parameters during chemoradiotherapy were recorded,and the differences of the parameters at different time points were analyzed and the parameters before treatment between the different therapeutic effect groups were compared.Results:During the course of treatment,the ADC values,D values,and D*values of NPC lesions showed a gradual upward trend,and f value increased first and then decreased after treatment.The mean values of ADC in the MRIpre group and the MRIpost group were 0.79×10-3 mm2/s and 1.56×10-3 mm2/s,respectively(PMRIpre vs MRIpost<0.001),and the D values were 0.67×10-3 mm2/s and 1.30×10-3 mm2/s,respectively(P MRIpre vs MRIpost<0.001).The f values in the MRIpre group and the MRI4th group were 10%and 18%,respectively(PMRIpre vs MRI4th<0.001).16 patients were included in the complete response group one month after the end of radiotherapy,and 17 patients were included in the partial response group.The D values of pretreatment in partial response group were significantly higher than that in complete response group(0.72± 0.1 0× 10-3 mm2/s vs 0.51 ±0.16×10-3 mm2/s,P =0.04).Conclusion:ADC and D values could monitor the efficacy of chemoradiotherapy for NPC.D values could be more reliable.IVIM-MRI could have application value for dynamically monitoring the efficacy of chemoradiotherapy in NPC.