Application Value Of Native T1-mapping,DKI And BOLD-MRI In Evaluating Renal Function In Patients With IgA Nephropathy

Objective:longitudinal relaxation time mapping(T1-mapping)detects tissue fibrosis,edema and other pathological changes by non-invasive means.Native T1-mapping does not need the help of contrast agents,so that patients with severe renal insufficiency can also be examined.Diffusion kurtosis imaging(DKI)can be used to quantitatively analyze water molecules in non-Gaussian diffusion motion in human tissues and reflects the corresponding pathophysiological changes in tissues and organs.Blood oxygenation level-dependent MRI(BOLD-MRI)takes changes in oxygen concentration of the body as natural contrast agents.Changes in the ratio of oxygenated hemoglobin to deoxygenated hemoglobin in tissues will cause changes in magnetic resonance signals,so as to evaluate the oxygenation state of tissues and organs.This study aims to explore the application value of native T1-mapping,DKI,and BOLDMRI in the evaluation of renal function in patients with IgA nephropathy(IgAN),and to compare the effectiveness of each magnetic resonance imaging(MRI)parameter.Methods:Fifty-seven IgAN patients in Affiliated Hospital of Nantong University diagnosed by biopsy and 19 healthy volunteers were included in this study.According to the severity of renal insufficiency and glomerular filtration rate,IgAN patients were divided into mild,moderate and severe chronic kidney disease groups.There were 19 healthy volunteers in the control group.All subjects were examined on 3.0T magnetic resonance instrument,and corresponding functional magnetic resonance pseudo-color images were generated on the workstation to obtain the corresponding renal MRI parameter values.The renal MRI parameters of CKD subgroups in the healthy control group and IgAN group were compared.Independent sample t test was used to compare the measurement data conforming to normal distribution between the two groups,Single factor analysis of variance was used for comparison between multiple groups,and LSD method was used for comparison between two groups.The rank-sum test was used to compare the data that did not conform to the normal distribution in the measurement data,and Analyzing the correlation between MRI data and renal function evaluation indicators such as e GFR,creatinine and cystatin C,etc by Pearson or Spearman correlation test.so as to explore the application value of multiple renal MRI in evaluating renal function in IgAN patients.Results:The difference of T1 value between control group and IgAN group was statistically significant [(1592.15±89.91)ms vs(1776.30±172.08)ms,P<0.001].Obviously,T1 values were higher in the IgAN group than in the control group.There were significant differences in T1 values among different IgAN subgroup [mild(1684.86±103.57)ms,moderate(1888.99±182.01)ms,severe(1969.14±133.74)ms;P<0.001],the more severe the renal function injuried,the greater the T1 value got.There was significant difference in Fak value between control group and IgAN group [0.15(0.08-0.20)vs 0.19(0.11-0.32),P<0.05],the Fak value of IgAN group was significantly higher than that of control group.The difference of Fak value between mild and severe CKD groups was statistically significant [0.17(0.11-0.25)vs 0.35(0.28-0.40),P<0.01],Compared with mild CKD group,the fak value of severe CKD group was significantly higher.There was no statistically significant difference in R2* value among groups.In IgAN group,T1 value was negatively correlated with e GFR(r=-0.620,P<0.001),hemoglobin(Hb)(r=-0.679,P<0.001),hematocrit(HCT)(r=-0.629,P<0.001),serum creatinine(Scr)(r=0.559,P<0.001),cystatin C(Cysc)(r=0.604,P<0.001).Fak was negatively correlated with e GFR(r=-4.004,P<0.05),and positively correlated with Scr(r=0.3658,P<0.05)and Cysc(r=0.378,P<0.01).MD was positively correlated with Hb(r=0.4717,P<0.001)and HCT(r=0.4983,P<0.001).There was no correlation between R2* value and clinical indicators.The area under the curve(AUC)of T1 value for predicting mild,moderate and severe impairment of renal function in IgAN are0.791(95%CI 0.660～0.922,P < 0.01),0.972(95%CI 0.914～1.000,P < 0.01)and0.988(95%CI 0.958～1.000,P < 0.01).The AUC of Fak value for predicting severe impairment of renal function in IgAN are 0.883(95%CI 0.678～1.00,P < 0.01).Conclusion:Compared with the control group,the values of T1 and Fak in IgAN group were significantly increased,and both were negatively correlated with e GFR and positively correlated with creatinine and cystatin C,suggesting that native T1-mapping and DKI have predictive value for renal function in IgAN patients.T1 value were statistically significant among all CKD subgroups,while Fak values were statistically significant only between mild and severe CKD groups,suggesting that the predictive value of native T1-mapping was superior to DKI.