The Study Of Multiple Diffusion-Weighted Imaging Models In The Diagnosis Of Cervical Cancer And Lymph Node Metastasis

Part I Intravoxel Incoherent Motion Diffusion-Weighted MRImaging of Cervical Cancer with Different b-values Objective:To evaluate the dependence of diffusion parameters on the b-values adopted for intravoxel incoherent motion(IVIM)diffusion-weighted magnetic resonance imaging(DW-MRI)and to investigate the application value of multiple diffusion parameters obtained from monoexponential and biexponential models in subjects with a normal cervix and in cervical cancer patients.Materials and Methods:A total of 120 female patients with cervical cancer and 21 female control patients with a normal cervix underwent DWI with 13 b-values(0-2000 s/mm2)at 3T.The standard apparent diffusion coefficient(ADC),diffusion coefficient(D),pseudodiffusion coefficient(D*)and perfusion fraction(f)were calculated by fitting with monoexponential and biexponential models at two different ranges of b-values:0-1000 and 0-2000 s/mm2.A univariate analysis was performed to identify factors that could distinguish cervical carcinoma from normal cervical tissue.Parameters that correlated with the pathological grade and stage of cervical cancer were also evaluated.Receiver operating characteristic(ROC)curves were used to evaluate the diagnostic efficiency of every parameter.Results:All the tested parameters,except the D* of the two different ranges of b-value groups,significantly differed between the patients with cervical carcinoma and normal controls(P<0.01).D2000,ADC2000 and D1000 showed comparable diagnostic value,with an area under the curve(AUC)of 0.923,0.909 and 0.907,respectively.ADC2000,D2000,ADC1000,and D1000 differed significantly among the three degrees of cervical stromal infiltration depth(P<0.05).Conclusion:D2000 and ADC2000 tended to outperform D1000 in terms of diagnostic efficiency,but there was no significant difference in their ability to differentiate cervical carcinoma from normal cervix.Cervical cancers with lower ADC and D values tended to have greater infiltration depth.Part II Differentiating Metastatic from Nonmetastatic LymphNodes in Cervical Cancer Patients using MultipleDiffusion-Weighted MR Imaging Models Purpose:To explore whether LN with high signal intensity on diffusion-weighted imaging(DWI)could be classified as metastatic or nonmetastatic and the diagnostic value of intravoxel incoherent motion(IVIM)in identifying them in cervical cancer.Materials and methods:Fifty female patients with cervical cancer underwent preoperative magnetic resonance imaging,including DWI with 13 b-values(0,50,100,150,200,300,500,800,1000,1300,1500,1700 and 2000 s/mm2)at 3T.Size parameters of lymph nodes(Size-S,Size-L,S/L Ratio)were measured.ADC was calculated by fitting with monoexponential odel.D,D* and f were calculated by fitting with biexoponentialmodel.These parameters were compared between the metastatic and nonmetastatic LNs groups.T-test was used if the data meet normal distribution,and the Mann-Whitney U test was used when the data did not comply with the normal distribution.Correlations among all parameters were assessed by using Spearman rank correlation.Receiver operating characteristic(ROC)curves were generated for each parameter to assess the area under the receiver operating characteristic curve(AUC)and to determine which parameter was optimal for the differentiation of LNs.Results:157 LNs with high signal intensity on multi-b value DWI was detected,41 of them were pathologically proved to be metastatic.The mean D and ? value of metastatic LNs were significantly higher than those of nonmetastatic LNs.However,the mean f value of metastatic LNs was significantly lower than that of nonmetastatic LNs(P<0.05).The mean Size-L,Size-S and S/L Ratio of metastatic LNs were significantly higher than those of nonmetastatic LNs(P<0.05).The Spearman rank correlation analysis showed that there were strong positive correlations between D and ADC,DDC,?,Size-L and Size-S(P<.01).The ROC analysis indicated that Size-S of LNs showed highest diagnostic value with AUC of 0.844,followed by S/L Ratio(0.726)and Size-L(0.694).The diagnostic values of D and f were lower with AUC no more than 0.70.The sensitivity for diffusion parameters to detect metastatic LNs was no more than 50%,and for size parameters was no more than 80%.Conclusion:Due to a limited sensitivity and specificity,diffusion parameters derived from IVIM are inferior to reliably discriminate metastatic from nonmetastatic LNs compared with size parameters in daily clinical routine.