Evaluation Of IVIM Combined With ASL For Early Renal Function Injury And Stage In Patients With Type 2 Diabetes Mellitus

Objective: To evaluate the value of IVIM and ASL in the assessment of early renal injury and stage in patients with type 2 diabetes mellitus(T2DM).Objects and methods: A total of 46 patients who were diagnosed with T2 DM in department of endocrine,Tianjin Medical University Metabolic Disease Hospital from September in 2018 to December in 2019.They were divided into normoalbuminuria group(NAU group,n = 26)and microalbuminuria group(MAU group,n = 20)according to the level of 24 h urinary microalbuminuria(UMA),38 healthy volunteers were recruited as normal control group(n=38).All of them were performed routine abdominal MR,IVIM and ASL with Philips Ingenia 3.0T MRI scanner.The true water molecular diffusivity(D),pseudo-diffusivity(D*),perfusion fraction(f)and renal cortical blood flow(RBF)were measured.One-way analysis of variance(ANOVA),chi-square test,and nonparametric test were used to compare the differences in general clinical data among the control group,NAU group,and MAU group.Intra-group correlation coefficient(ICC)was used to compare the consistency of IVIM and ASL parameters measured by two observers.Paired sample t test was used to test whether there was any difference in the values of IVIM and ASL parameters between the left and right kidneys,as well as the difference in the values of IVIM parameters between the renal cortex and medulla.ANOVA was used to compare the differences in the values of IVIM and ASL parameters in renal cortex and medulla between the subjects.Pearson correlation analysis was used to compare the correlation between IVIM,ASL parameters and biochemical indexes,as well as the correlation between ASL parameters(RBF value)and IVIM parameters(the value of D* and f).Binary logistic regression and ROC curve were used to analyze the value of IVIM and ASL parameters separately and their combined application in the diagnosis of early renal injury and stage in T2 DM patients,and the optimal diagnostic threshold and the most sensitive indicators were determined.Results:(1)There was no statistical difference in gender,age,height,SBP and DBP in the three groups(all P>0.05).Compared with control group,the body weight(P<0.001,P<0.01),BMI(P<0.001,P<0.001)and BSA(P<0.001,P<0.01)in NAU and MAU group were significantly increased.The serum Scr was significantly increased and e GFR was significantly decreased in MAU group,which was statistically significant different from the control group(all P<0.05)and NAU group(all P<0.01).There was no statistically significant difference in disease course,FPG,2h PBG,BUN,Hb A1 c,TG,TC,HDL-C,LDL-C and UA levels between the NAU and MAU group(all P>0.05),but the level of 24 h UMA in MAU group was significantly higher than that of the NAU group(P<0.001).(2)The values of D,D*,f,RBF in the renal cortex,and D,f in the medulla measured by the two observers showed good reproducibility(all ICC > 0.75),the value of D* in the medulla was moderately consistent(0.4 ≤ ICC < 0.75).(3)There was no statistically significant difference in IVIM and ASL parameters between left and right kidneys(P> 0.05).(4)The values of D and f in the renal cortex were higher than medulla,D* in the medulla was higher than cortex,the difference was statistically significant(all P< 0.01).(5)The overall difference of IVIM and ASL parameters between subjects in the control group,NAU group and MAU group were statistically significant(all P< 0.05).Compared with the control group,the values of D(P<0.01),f(P<0.01),RBF(P<0.01)in the cortex and D(P<0.05)in the medulla increased significantly in NAU group,the values of D(P<0.01),f(P<0.05),RBF(P<0.001)in the cortex and D(P<0.05),D*(P<0.01),f(P<0.01)in the medulla were significantly decreased in the MAU group.Compared with NAU group,the values of D(P<0.001),D*(P<0.05),f(P<0.001),RBF(P <0.001)in the cortex and D(P<0.001),D*(P<0.01),f(P<0.01)in the medulla were significantly decreased in the MAU group.(6)The values of D,f and RBF in the cortex were significantly positively correlated with e GFR(r=0.737,P<0.001,r=0.616,P<0.001,r=0.693,P<0.001),negatively correlated with Scr(r=-0.573,P<0.001,r=-0.564,P<0.001,r=-0.572,P<0.001)and 24 h UMA(r=-0.676,P<0.001,r=-0.696,P<0.001,r=-0.575,P<0.001),D* was weakly correlated with e GFR(r=0.294,P<0.01)and 24 h UMA(r=-0.380,P<0.01).The values of D in the medulla was significantly positively correlated with e GFR(r=0.664,P<0.001),and negatively correlated with Scr,24 h UMA(r=-0.503,P<0.001,r=-0.541,P<0.001),while f and D* were weakly correlated with e GFR(r=0.397,P<0.001,r=0.333,P<0.01),Scr(r=-0.292,P<0.01,r=-0.246,P<0.05),24 h UMA(r=-0.377,P<0.05,r=-0.386,P<0.01).The values of RBF were significantly positively correlated with D and f in the cortex(r=0.636,P < 0.001),but no correlation with D*(P>0.05).(7)The values of D in the cortex and medulla,also the values of f and RBF in the cortex showed a high diagnostic efficacy at the different stages of renal function in patients with T2 DM,followed by the values of D* in the cortex and medulla and f in the medulla.Combination of IVIM and ASL indexes,showed more effective in the diagnosis of early renal injury and the stage in T2 DM than their applications respectively.Conclusions: IVIM and ASL can noninvasively evaluate the characteristics of water molecule diffusion,microcirculation perfusion and blood flow changes in patients with T2 DM at the different stages of renal function,also reflect the filtration function of the kidney.Combined with IVIM and ASL showed a better diagnostic efficacy of the early renal function injury and stage in patients with DKD,its accuracy is higher than that of separate application,sensitivity is higher than 24 h UMA.