Multi-parameters MRI Study On The Diabetes Kidney Disease

Backgrouds and objective:According to the latest data of International Diabetes Federation(IDF),diabetes mellitus(DM)have become a global chronic disease.The number of DM was 415 million and the number of China was 109 million in 2015.Forty percent of DM patients will develop to diabetic kidney diseases(DKD),resulting of kidney is one of the major target organ of diabetes.DKD,one of common complications of diabetes,is the primary reason leading to the end-stage renal disease(ESRD)currently.Pervious pathophysiology studies have demonstrated that perfusion,oxygenation and water molecule diffusion were three main function changes in the process of DM.Renal blood flow was involved in the early state of DM.Hyperglycemia worked on microvascular of the kidney leads to a decrease of renal microvascular diameter and perfusion.Compensation mechanisms had been activated by hypoxia of kidney.Renal function and blood flow were enhanced until it worked out.At the same time,the oxygenation level increased in initial stage and then declined as change of kidney perfusion.When the structure of cortex and medulla proliferated even hyperplasia or fibrosis,the water diffusion in the collecting system will also been restricted.Without promptly treatment,the DM will eventually develop to ESRD.Due to compensation capability,indicators of kidney were still within normal limits in the initial stage.Therefore,diagnosis should be made as early as possible and before the advanced stage to avoid missing the best treatable stage.Current routine examination was invasive or require exogenous contrast agent,and was not able to detect abnormalities in the early stage.As the majority of previous studies just focused on one aspect of the change in perfusion or oxygenation level,an integrated,comprehensive analysis of the renal function was needed.In order to promote the awareness of the DKD and to do the early detection and diagnosis,the process of disease need to be further understood.A simple way is therefore needed to observe renal alterations and assess renal function under diabetic state from the perspectives of perfusion,oxygenation and water molecule diffusion.With the development of magnetic resonance imaging(MRI),there are many new technologies and methods such as arterial spin labeling(ASL),blood oxygenation level dependent(BOLD)and diffusion tensor imaging(DTI)functional MRI(fMRI)have been introduced into clinic.These technologies provide reliable and noninvasive ways for solving clinical predicament.In order to further understand the pathophysiological mechanisms of DKD and provide theoretic support for early detection.ASL,BOLD and DTI were used to evaluate the renal function via comparing and observing renal perfusion,oxygenation and water molecule diffusion changes in this study.Furthermore,the relationship between the renal function index and MRI parameters was also analyzed.Materials and Methods:1.Evaluate the renal cortex perfusion of diabetes mellitus using ASL MRIFifty type 2 diabetes mellitus(T2DM)and 25 normal control(NC)volunteers were enrolled in this study.Based on the Kidney Disease Outcome Quality Initiative(K/DOQI)classification of stages of chronic kidney disease(CKD)and DKD diagnostic criteria,T2 DM patients were divided into three subgroups by senior endocrinology doctor of our hospital.1.DKD mild group(n=11): diagnosed T2DM;albumin creatinine ratio(ACR)>300 and diabetic retinopathy accompany CKD;estimated glomerular filtration rate(eGFR)?60 ml/min·1.73m2.2: DKD moderate-severe group(n=14): diagnosed T2DM;albumin creatinine ratio(ACR)> 300 and diabetic retinopathy accompany CKD;eGFR < 60 ml/min·1.73m2.3.simple diabetes(SD)group(n=25): diagnosed T2DM;urine protein test was negative;Diabetic retinopathy and other chronic kidney disease were excluded.ASL MRI and normal sequences were conducted on a Siemens Magnetom Trio 3.0T scanner with 8-element torso phased array coil for signal reception.ASL image were postprocessed to get cortex of renal blood flow(cRBF)value of cortical using Matlab R2013 a and ImageJ software.Statistical analysis was performed using the software SPSS 18.0.Using interclass correlation coefficient(ICC)to analyze the consistency of c RBF value measured by two radiologists.One-way analysis of variance(ANOVA)and LSD were used to compare the different cortical c RBF among four groups.In addition,Pearson correlation coefficients was used to evaluate correlation between cRBF and eGFR.A threshold of P < 0.01 was considered as statistical significance.2.Evaluate the renal oxygenation levels and water molecular diffusion of diabetes mellitus using BOLD,DTI MRITwenty-five simple diabetes(SD)patients,20 DKD patients and 26 normal control(NC)volunteers were enrolled to the study.Gender,age and BMI were matched in three groups.Random urine and venous blood were collected for biochemical analysis in the morning before MRI examination.The eGFR value was calculated according to equations of modification of diet in renal disease(MDRD).Conventional T1,T2 sequence were collected to exclude organic diseases by 3.0T MR scanner.After that,multi-gradient-echo(m GRE)series of BOLD and echo-planar imaging(EPI)series of DTI were scanned,and obtained images were processed on Siemens post-processing workstation.R2* value,FA,ADC values of cortex and medulla were got by sketching the region of interest(ROI)of a single kidney.SPSS 18.0 software was used to analysis data of MRI.Ages and BMI of three groups were analyzed by ANOVA,while gender was analyzed with chi-square test.The difference of R2*,MCR,FA,ADC value between left and right kidney analyzed with paired samples t test.If there was no difference in left and right kidney,mean values were subsequently used for statistical analysis.The R2*?MCR?FA?ADC values of kidney cortex and medulla were analyzed by ANOVA and their relations with eGFR were analyzed with Pearson correlation analysis.Results:1.Cortex perfusion of DKD: There were no statistical difference between left and right kidney cRBF value of four groups applying paired t test to perform statistical analysis.So that their mean value was used as an individual kidney cRBF value.With an ICC of c RBF values larger than 0.90 in different groups showed good consistency between two radiologists.ANOVA showed cRBF values statistical significance among four groups(F=20.66,P<0.01),that cRBF values of DKD moderate-severe group was significant lower than other gourps.The Pearson correlation analysis showed that cRBF value in diabetic patients were significantly positive correlation with their eGFR(r = 0.646,P<0.01).2.Oxygenation levels and water molecular diffusion of DKD: Significant difference had been found in MCR and medulla FA values among three groups.MCR value of SD group were higher than DKD group(P=0.001)and NC group(P=0.005).Medulla FA value of SD group were higher than NC group(P=0.005),and DKD group was lower than SD group(P<0.01)and NC group(P=0.011).Pearson correlation analysis showed positive correlation between MCR values(r=0.545,P<0.01),Medulla FA value(r=0.406,P=0.006)and eGFR in diabetic patients.Conclusion:This study found that c RBF value of DKD moderate-severe group was significantly lower than other groups and c RBF value can response level of glomerular filtration rate,which indicated DKD aggravate the kidney damage and ASL MRI can accurately,simply and safely assessment of renal cortex perfusion function in patients with diabetes.MCR and FA values were more sensitive to the change of renal than other parameters.Therefore,DTI and BOLD MRI can be used to evaluate renal function and detect metabolism and water diffusion changes early in the kidney of healthy people and diabetic patients.