Clinical Studies Of FMRI In Diagnostic Value In Acute Renal Rejection

Objective:To study of diffusion tensor imaging (DTI) and blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) in the diagnosis of renal transplantation on AR and the differential diagnosis between AR and ATN, and to explore a sensitive, noninvasive strategy of evaluating renal allograft function.Subjects and Methods:This study was approved by the local ethics committee; written informed consent was obtained for all subjects. Between May2012and March2014,60renal allograft recipients2-3weeks after transplantation were included in this study and examined using a fat-saturated echo-planar DTI and GRE-BOLD sequence in oblique-coronal orientation at3.0Tesla magnetic resonance (MR) imager (diffusion directions=6, b=0,300s/mm2). According to the clinical diagnosis and pathological biopsy results, all patients were divided into three groups:normal renal function group, acute rejection group and acute tubular necrosis group. Mean apparent diffusion coefficient (ADC) and mean fractional anisotropy (FA) and R2*values were determined separately for the cortex and the medulla and compared among3groups. Differences in FA and ADC and R2*values between the cortex and medulla in each group were compared using paired samples t test. Differences in FA and ADC and R2*values of the cortex and medulla between each group were compared using one way ANOVA test. Meanwhile, the receiver operating characteristic (ROC) curves was used to analyze the differential diagnostic efficacies of cortical ADC value and medullary ADC value and medullary R2*for renal allografts with different renal function. P<0.05indicated a statistically significant difference. Meanwhile, relationships between R2*and ADC of renal allografts were assessed by using Pearson correlation coefficient. Results:(1) Mean FA values in the medulla were higher than in the cortex in all three groups (P<0.01). Mean ADC value in the medulla was lower than in the cortex in normal renal function group (P<0.05), while the differences of mean ADC values between medulla and cortex were equal to each other in the other two groups (P>0.05);(2) There were no significant differences of mean FA value in the cortex among all groups (P>0.05);(3) There were no significant differences of mean FA value in the medulla among all groups (P>0.05);(4) Mean ADC values in the cortex between normal renal function group and ATN group didn’t show pronounced differences (P>0.05), but they were both higher than AR group (P<0.05);(5) There were no significant differences of mean ADC values in the medulla between normal renal function group and ATN group (P>0.05), while mean ADC value in the medulla in AR group was lower than that in normal renal function group, and the difference was significant (PO.01). Meanwhile, mean ADC value in the medulla of AR group was significantly lower than ATN group (P<0.05);(6) Mean R2*in the medulla were higher than in the cortex in all three groups (P<0.05);(7) There were no significant differences of mean R2*in the cortex among all groups (P>0.05);(8) Mean R2*in the medulla between normal renal function group and ATN group didn’t show pronounced differences (P>0.05), but they were both higher than AR group (P<0.05);(9) Cortical ADC value and medullary ADC value and medullary R2*could distinguish renal allogafts with different renal function, and the sensitivity、 specificity、positive and negative predictive values were all more than70%. However, the differential diagnostic efficacies of these three parameters were almost same with each other (P>0.05);(10) In renal allografts, there was no significant correlation between cortical R2* and cortical ADC (r=0.217, P>0.05), meanwhile, no significant correlation between medullary R2*and medullary ADC (r=0.171, P>0.05).Conclusion:DTI and BOLD can identify transplanted renal AR and ATN noninvasively, and mean ADC value in the cortex and medulla can be used as index for the diagnosis of renal transplantation AR.