The Value Of 3.0T MR Diffusion Tensor Imaging In Chronic Kidney Disease

Part one MR diffusion tensor imaging of healthy kidneyObject: To study the diffusion tensor imaging of normal kidneys and investigate the effect of different b values on the diffusion tensor imaging parameters(ADC value,FA value)and image quality.Obtaining the best b value of renal diffusion tensor imaging,to establish the reference ranges of the ADC value and FA value of normal renal cortex and medulla.Materials and methods: MR routine and DTI sequence scan were performed for 30 healthy volunteers selected in our study by using a GE Signa HDxt 3.0T superconducting magnetic resonance scanner.DTI scan used breath gating technique,selected single-shot spin-echoe echo-planar imaging sequence and 6 diffusion gradient directions.B value was selected as 0,200,400,600,800,1000s/ mm2.The images were processed by the Functool2 software of the GE ADW4.4 workstation.The ADC values,FA values and SNRs were measured,and the ADC maps were scored qualitatively.SPSS 21.0 software was used to analyze the changes of ADC value.FA value and SNR caused by different b values.Results: The ADC values of renal cortex and medulla were significantly different among the five groups(F values were 34.639,42.552,respectively;P <0.001),and the ADC value were decreased with the increase of b value;The difference of FA value of renal cortex and medulla was not statistically significant in the five groups(F values were 2.791,0.747,respectively;P> 0.05);Comparing healthy adult renal cortex and medulla,the ADC value of renal cortex was higher than that of medulla,while FA value was lower than that of medulla,the difference was statistically significant(all P <0.05);SNR and the scores of ADC map were decreased with the increase of b value.When the b value was more than 800 s / mm2,the ADC map was poor and the boundaries of the cortex and medulla were unclear.The score of FA map did not have diagnostic significance.Conclusion: When b value of kidney DTI imaging is 600 s / mm2,the image quality is better,the boundaries of the cortex and medulla are clear,and it is suitable for kidney clinical research.Part two Evaluation of renal function and pathological damage in patients with chronic kidney disease by 3.0T magnetic resonance diffusion tensor imagingObject: To assess the clinical value of 3.0T magnetic resonance diffusion tensor imaging parameters(the ADC value and the FA value)for renal function and pathological damage of patients with chronic kidney disease.Materials and methods: Thirty-four patients with CKD diagnosed clinically in our hospital from December 2015 to August 2016 were examined by MR routine and DTI sequence scan,and undergo a renal biopsy within 7 weeks after the examination.CKD patients were divided into two subgroups according to the degree of pathological damage(mildly injured group and moderate-severe injured group),30 healthy adult volunteers served as control group.The ADC value and FA value was measured in the normal control group and CKD lesion group.The difference between the normal control group and the CKD lesion group was compared.The relationship between ADC value and FA value and renal function index(Scr,24-upro and eGFR),clinical stage and pathological damage(glomerular injury,renal tubulointerstitial injury and small vessel injury)was analyzed,respectively.Results:The ADC values and FA values of renal cortex and medulla were significant differences among the control group,the mild injury group and the moderate-severe injury group(all P <0.05);The ADC value and FA value of renal cortex medulla was decreased with the degree of pathological damage increased.There was a positive correlation between renal medulla ADC value,FA value and eGFR in CKD patients(r = 0.375,P <0.05;r = 0.874,P <0.001),but negatively correlated with Scr,24-upro and CKD staging(all P<0.05),and the correlation of renal medulla FA value was significantly higher than that of the ADC value.The ADC value of the renal cortex was negatively correlated with renal tubular-Interstitial score(r =-0.360,P <0.05).Medulla FA values were positively correlated with glomerular lesion score,renal tubulointerstitial injury score and small vessel injury score(r =-0.738,-0.828,-0.368,respectively;all P <0.05).Identify the control group and the mild injury group,the medulla FA value showed better diagnostic ability with accuracy of 0.87.When the best diagnostic value of medulla FA value was 0.445,the sensitivity and specificity were 78.6%,90.00%,respectively.Conclusion: DTI can invasively evaluate the renal function changes and renal pathological damage in patients with chronic kidney disease.In particular,medulla FA value can reflect glomerular injury and the degree of renal tubular-interstitial fibrosis.DTI showed a better diagnostic value for the early pathological damage of patients with chronic kidney disease.