Using Intravoxel Incoherent Motion(IVIM) MR Imaging To Evaluate Renal Function In Early Diabetic Nephropathy

Purpose:The objective of this study was to evaluate the utility of IVIM parameters to identify the early changes in DN. Materials and Methods:Forty type Ⅱ diabetic patients and 20 healthy control subjects underwent IVIM sequence(b=0,30,50,80,100,150,200,300,500,800,1000s/mm2) on a 3.0T MRI scanner. Diabetics were stratified by albumin-creatinine ratio(ACR) into 2 groups: NAU(ACR<30mg/g; n=20) and MAU group(ACR30~300mg/g; n=20). Mean cortical and medullary IVIM parameters(D, D*, f and ADC values) were calculated by setting multiple regions of interest. Differences in every IVIM parameter among the three groups were assessed. Also, they were correlated with ACR and estimated glomerular filtration rate(e GFR). Result:Mean cortical D,D*,f and ADC values in Control group are 1.77×10-3mm2/s, 13.59×10-3mm2/s, 24.07% and 2.08×10-3mm2/s,respectively; Mean medullary D,D*,f and ADC values in Control group are 1.68×10-3mm2/s, 13.15×10-3mm2/s, 19.44% and1.96×10-3mm2/s, respectively. Mean cortical D,D*,f and ADC values in NAU group are 1.72×10-3mm2/s, 15.83×10-3mm2/s, 30.36% and 2.07×10-3mm2/s respectively; Mean medullary D,D*,f and ADC values in NAU group are 1.62×10-3mm2/s, 16.7×10-3mm2/s, 23.44% and 1.93×10-3mm2/s, respectively.Mean cortical D,D*,f and ADC values in MAU group are 1.65×10-3mm2/s, 13.91×10-3mm2/s, 31.84% and 2.00×10-3mm2/s, respectively; Mean medullary D,D*,f and ADC values in MAU group are 1.58×10-3mm2/s, 12.27×10-3mm2/s, 20.32% and 1.88×10-3mm2/s, respectively.Mean medullary and cortical D values in NAU group was significantly lower than those in Control group(pm<0.001, pc=0.008).And mean medullary and cortical D* and f values in NAU group were significantly greater than those in Control group(D*: pm =0.009, pc =0.031;f: pm =0.001,pc<0.001). MAU group showed significantly lower mean D or ADC values in cortex and medulla and greater f value in cortex compared with the control group(D:pm =0.001,pc<0.001 ADC; ADC: pm =0.001,pc =0.007; f: P<0.001).The average D and ADC of renal cortex and medulla correlated with with ACR in MAU group(D :rc=-0.778,p<0.001; rm=-0.785,p<0.001; ADC:rc=-0.469,p=0.037; rm=-0.559,p=0.010). Conclusion:IVIM may be helpful in identifying the early-stage DN(ACR<30mg/g). D, D* and f values, especially D, may be more sensitive than ACR to detect early-stage injury.