The Value Of Intravoxel Incoherent Motion Diffusion-weighted Imaging In Differential Diagnosis Between Primary Nasopharyngeal Carcinoma And Chronic Nasopharyngitis

Objectives:This study aimed to investigate the value of the parameters of mono-exponential model Diffusion weighted imaging（DWI）and intravoxel incoherent motion diffusion-weighted imaging（IVIM-DWI）for differentiation between the primary nasopharyngeal carcinoma and chronic nasopharyngitis.Materials and methods:32 patients with primary nasopharyngeal carcinoma and 20 patients with chronic nasopharyngitis diagnosed by nasopharyngoscopy biopsy in the second affiliated hospital of the university of south China from June 2018 to June 2019 were collected.All cases were performed conventional MRI scan,DWI（0,800s/mm²）,IVIM DWI（13 b values:0,10,20,30,50,80,100,150,200,300,400,600,800s/mm²）examination.8-channel head-neck combination coil was used in MRI.Quantitative parameters of IVIM-DWI and DWI were measured by the post-processing software of GE ADW4.6 workstation.The differences of ADC,D,D*and f values between the primary nasopharyngeal carcinoma group and the chronic nasopharyngitis group were compared.The individual characteristic curve（ROC）of monoexponential and biexponential model diffusion weighted imaging for differentiating nasopharyngeal carcinoma（NPC）from chronic nasopharyngitis was drawn,and the area under the curve（AUC）was calculated to determine the diagnostic threshold of each parameter.SPSS 25.0 software was used for statistical analysis of the data.Two independent samples t-test was used to analyze the experimental data between the two groups.P<0.05 was considered statistically significant.Results:Thirty cases of nasopharyngeal carcinoma and twenty cases of chronic nasopharyngitis finally met the inclusion criteria.Statistical analysis showed that ADC value and D value of nasopharyngeal carcinoma group were significantly lower than that of chronic nasopharyngitis group,and the differences were statistically significant（P<0.01）.There was no statistically significant difference in D*value and f value between the two groups.The area under the ROC curve（AUC）of D value was the largest（0.913）,greater than that of ADC.When the threshold value of D was 0.612×10^-3mm²/s the sensitivity,specificity and accuracy of the diagnosis of primary nasopharyngeal carcinoma were0.833,0.950 and 0.783 respectively.Conclusion:IVIM-DWI and DWI related parameters have certain diagnostic value in the differential diagnosis of primary nasopharyngeal carcinoma and chronic nasopharyngitis,and D value has higher diagnostic efficiency.