Application Value Of IVIM Imaging In Differential Diagnosis Of Rectal Adenoma And Adenocar-Cinoma And In T Staging Of Rectal Adenocarcinoma

ObjectiveTo evaluate the value of intravoxel incoherent motion（IVIM）imaging in differential diagnosis of rectal adenoma and adenocarcinoma and in T staging of rectal adenocar-cinoma.Materials and Methods75 patients with rectal neoplasm proved by surgical pathology,including 21 cases of rectal adenoma and 54 cases of adenocarcinoma were selected into this study.Among the rectal adenocarcinoma,the cases of T1 staging was 7,T2 staging was 15,T3 staging was23,T4 staging was 9.Among all the patients,46 were male and 29 were female;the age range from 30 to 80 years old and the average age was 59 years old.All patients underwent GE HD750 3.0T IVIM imaging before operation.The values of IVIM parameters:true diffusion coefficient（D）,perfusion-related diffusion coefficient（D*）and perfusion fraction（f）measured on a AW4.5 work station were analyzed.The differences of D,D*and f values were compared by independent samples t-test between the rectal adenoma and adenocarci-noma groups.The ROC curve was plotted and then the area under the curve（AUC）,sensitivity and specificity were analyzed to assess the diagnostic performance of IVIM parameters with statistical difference.The differences of parameters D,D*and f values were compared by One-Way ANOVA between different T stage groups of rectal adenocarc-inoma.The differences of parameter between each two T stage group were further analyzed when there was statistical difference between different T stage groups.The P<0.05 was considered statistically significant difference.Results1.The difference of IVIM imaging parameters between rectal adenoma and adenocarcinoma group:The D values in adenoma group and adenocarcinoma group were（0.892±0.101）×10^-33 mm²/s and（0.730±0.089）×10^-33 mm²/s respectively,and the D value in adenocarcinoma group was lower than that of the adenoma group,the difference was statistically significant（t=6.807,P<0.05）.D*values in adenoma group and adenocarci-noma group were（7.371±2.649）×10^-33 mm²/s and（8.513±2.720）×10^-3 mm²/s respectively,and the D*value in adenocarcinoma group was higher than that of the adenoma group,and the difference was not statistically significant（t=-1.644,P>0.05）.F values in adenoma group and adenocarcinoma group was 0.321±0.062 and 0.276±0.069 respectively.The value of f in adenocarcinoma group was lower than that of the adenoma group.The difference was statistically significant（t=2.611,P<0.05）.The AUCs of D,f values in the two groups were 0.895,0.701 and further analysis showed the differences between the two were statistically different（P<0.05）.At the cutoff of 0.794×10^-3mm²/s,0.279 for D and f,the corresponding sensitivities were 81.48%,61.11%and the corresponding specificities were 90.48%,80.95%.2.The difference of IVIM imaging parameters between different T stages of rectal adenocarcinoma:The value of D in T1-T4 were（0.822±0.109）,（0.776±0.068）,（0.710±0.060）and（0.635±0.047）×10^-33 mm²/s respectively,D value decreased gradually and the difference was statistically significant（F=12.906,P<0.05）;LSD test showed that the difference in D value between T1 and T3,T1 and T4,T2 and T3,T2 and T4,T3 and T4were statistically significant（P<0.05）.The value of D*in T1-T4 were（7.321±2.568）,（7.979±2.552）,（8.879±2.606）and（9.396±3.310）×10^-3mm²/s respectively,D value increased gradually and the difference was not statistically significant（F=1.012,P>0.05）;The value of f in T1-T4 were 0.267±0.060,0.280±0.054,0.274±0.084 and 0.280±0.067respectively,the difference was not statistically significant（F=0.068,P>0.05）.Conclusion1.The D and f values of the IVIM imaging can differentiate rectal adenoma and adenocarcinoma to some extent.The diagnostic efficiency of the D value is higher than the f value.2.The D value of the IVIM imaging has a certain reference value for the diagnosis of rectal adenocarcinoma T staging.