The Application Of Diffusion Weighted Imaging Based On Monoexponential And Biexponential Model In The Diagnosis Of Benign And Malignant Lung Nodules/Masses

Objective:To compare the value of lesion-to-spinal cord ratio?LSR?,apparent diffusion coefficient?ADC?and intravoxel incoherent motion?IVIM?parameters in the differention of pulmonary nodules and masses,and to explore the preferred region of interest?ROI?selection method.Methods:63 patients?42 males,21 females;age,32-82y,mean 59.3y?,a total of 63lesions?18 cases of benign,45 cases of malignant?showed as pulmonary nodules?n=26?or masses?n=37?were included.MRI routine plain scan,free-breathing DWI and IVIM scans were performed on Siemens 3T MRI.LSR was drawn on DWI images?b=800 s/mm²?to derive the signal ratio of lesion-to-spinal cord and cited as LSR₈₀₀.And ADC and IVIM parameters were analyzed by the single-slice method?ROI_s?and volume method?ROI_v?on ADC maps and IVIM images to derive the mean ADC value(ADC_mean),the minimum ADC value(ADC_min)and IVIM parameters D,D*,f.Inter-observer reproducibility were assessed with intraclass correlation coefficients?ICCs?.The paired sample t test was used to compare the differences between the values obtained by ROI_s and ROI_v in lung nodules and masses respectively.The differences between the parameters of benign and malignant lung nodules and masses were compared by using the independent sample t test?normal distribution?.Receiver operating characteristic?ROC?curves were generated to identify the best parametersto distinguish the benign and malignant lung nodules and masses.Results:The inter-observer reproducibility of IVIM perfusion parameters D*was relatively poor.There were no significant differences in ADC_mean,ADC_min,D and f values obtained by single slice ROI method and the volumetric ROI method?t=-2.316;P=0.029?.For lung nodules,only ADC_mean?ROIs?existed difference between benign and malignant nodules.For lung masses,ADC_mean,ADC_min?ROI_v?,D and f?ROI_s?all have the diagnostic value,and IVIM pure diffusion parameter D by volumetric analysis has the largest diagnostic value.Conclusion:The diagnostic ability of DWI of pulmonary masses is higher than that of pulmonary nodules.For lung nodules,only the mean ADC value obtained by single slice ROI method has the diagnostic value.For lung nodules,ADC_mean,ADC_min,D and f values all have the diagnostic value,but D obtained by volumetric analysis has the largest diagnostic value.