Comparative Study Of MR Imaging And Urine Protein Excretion Rate In Early Stage Of Diabetic Nephropathy

Research backgroundDiabetic nephropathy (diabetic nephropathy, DN) is one of the maincomplications of diabetes. In recent years,, the prevalence of diabeticnephropathy had increased rapidly. The high morbidity and high mortality rateof DN had brought heavy burden for patients’ family and for the all society.If DN could be timely intervention in early state, the renal impairment isoften reversible. Once diabetic patients enter clinical nephropathy, thereare often difficult to reverse the progress of the lesions. The exactpathogenesis of DN remains not to be elucidated. The factors such as long-termhyperglycemia, end products of advanced glycation, increased polyol pathwayactivity, increased protein kinase C activity and increased glomerularpressure play an inportant role in the pathogenesis of DN. These factorsdirectly lead to morphological changes in the kidneys such as glomerularhypertrophy,glomerular basement membrane and the tubular basement membranethickening,increased mesangial matrix, hyalinosis of golmerular arteriolar.Although in recent years researchs with biomarkers reflect a variety of earlydiabetic renal changes has made great progress,but had not perfect due tovarious physiological changes, pathological changes and the technicalcondition itself. At present,the main mark for diagnosis of DN on clinicalis the occur of persistent microalbuminuria(MAU). Urinary albumin excretionrate(UAER) results as the gold standard for diagnosis DN. There are stillmany interference factors in the process of taking samples and thedetection,such as poor reproducibility, disease course, age, blood glucoseand blood lipid level and so on. Only on the basis of the results of UAERdoes not accurately reflect the risk of DN and development trend.As a non-invasive examination technique,in recent, MRdiffusion-weighted imaging(DWI) and MR diffusion tensor imaging(DTI) had become a research hotspot because of reflecting the whole change of renalfunctional. Kidney become a ideal organ of diffusion weihgted imaging becauseof high moisture content and special anatomical and physiological structure.This research observed the renal changes in DWI and ADC map, DTI and FA mapin different periods of diabetic patients. To compared the differences ofrenal parenchymal ADC value and FA value in different perion of renal changesin type2diabetes patients,especially the ADC and FA value change in theearly diabetic renal damage.This research study of DWI and DTI magneticresonance imaging in the diagnosis of diabetic nephropathy, in the hope ofearly renal lesion was found in diabetic patients.Study objectiveDiscussion MR DWI and DTI scanning with ADC value,FA value of the kidneyon various stages of renal alterations in diabetic patients,and therelationship between UAER. Evaluation the diagnostic value of DWI and DTIin early stage of DN. Evaluation the relationship between DWI,DTI and someserologic markers such as serum creatinine(Scr) and serum cystatin C(cys C).MethodThis study included30patients whom had diagnosed as type2diabeticpatients in our hospital. Then divided all patients to2groups accordingto UAER outcome:①normal UAER group (8hours overnight urinary albuminexcretion rate <20ug/min),②the abnormal urinary UAER group (20ug/min≤8hours overnight urinary albumin excretion rate≤200ug/min)，12personsto be the normal control group,all were normal renal function of healthysubjects. All patients and normal controls underwent routine MRI and DWI,DTI scanning. DWI scanning process using b=400s/mm~2,500s/mm~2,600s/mm~2and800s/mm~2kidney when other parameters are the same,axial and coronalDWI scanning were be taken. With ADC value as indicators, comparison of thedifference of ADC value in different groups, comparison of the difference of renal ADC values under different b values,and combinate with serumcreatinine,serum cystatin C of patients for correlation analysis.DTI scanwith b=500s/mm~2, kidney coronal DTI scanning, FA value as indicators,comparison of the difference of renal cortical and medullary FA value indifferent group.Result1. general information: all of the42volunteers,14cases of normalUAER group,16cases of abnormal UAER group,12cases in the controlgroup, between the three groups in terms of age, gender, concomitantdiseases and general aspects are no statistical difference (P>0.05).2. The general regularity analysis of DWI and DTI:in DWI scan,along withthe increase of b value, ADC value decreased. The higher the b valueis, the lower the image SNR is. On both sides of the renal parenchymaADC values in various b values were not statistically different (P>0.05); DTI scanning On both sides of the renal corticomedullary FAvalues are no statistical difference (P>0.05); Kidney medulla FAvalues are no statistical difference (P>0.05) between man and awoman.3. In the results of DWI scan, the correlation analysis of UAER and ADCindicated when B=400and600s/mm~2, ADC and UAER were significantlynegatively correlated (P <0.05); the Pearson correlation analysisbetween age and ADC value showed no correlation was found between.Under all b values, normal UAER group of renal parenchyma ADC valueswere significantly lower than those in normal control group (b=400s/mm~2, P=0.015; b=500s/mm~2, P=0; b=600s/mm~2, P=0.001;b=800s/mm~2, P=0.008), the difference of Abnormal UAER group ofrenal parenchymal ADC and normal control group was greater than theprevious two groups (b=400s/mm~2, P=0.000; b=500s/mm~2, P =0.000; b=600s/mm~2, P=0.000; b=800s/mm~2, P=0.000). Thereis no statistically significant differences at all b values of therenal parenchyma ADC values between two prevalence group. In theresults of DTI scan, renal medullary FA in the normal UAER group wassignificantly higher than that in normal control group (P=0.016).Renal medullary FA in abnormal UAER group was significantly higherthan that in normal control group (P=0.004), The renal medullaryFA of two prevalence group was no statistically difference(P=0.106).There were not statistically significant (P>0.05) in the threegroups of renal cortical FA values.4. Relevance of other indicators reflecting kidney function and imagingresults: In this study patients’ serum creatinine were below thethreshold. There is no obvious correlation between two prevalencegroups in renal parenchyma ADC and serum creatinine. The correlationbetween similarly not found in two diseased group of renal parenchymaADC value and serum cystatin C.Conclusion1. in normal albuminuria group of type2diabetic patients, DWI has shownbetween normal controls and differences, prompting DWI determination is type2diabetes diagnosis of early renal damage sensitivity is urine albuminquantitative detection of higher detection method, contributes more to earlydetection and quantitative assessment of type2diabetic patients with renaldamage.2.two prevalence of group ADC value have no statistically significantdifferences between the renal parenchyma, but abnormal urinary UAER groupof renal parenchyma average ADC value is lower than the normal urinary UAERgroup, tips with diabetic renal damage in the progress of renal parenchyma, ADC value decreases continuously, DWI scan may be reflected in the DN processa new index.3.DTI from the view point of imaging reflect renal tubular lesions, makeup for the UAER focuses on reflecting the glomerular injury, combined withDWI will be more comprehensive reflection of early renal changes trend ofDN, contributing to the overall on the DN early kidney lesion assessment.