The value of blood oxygen level dependence and arterial spin labeling MRI in the early diagnosis of renal allograft dysfunction / 中华放射学杂志

ABSTRACT

Objective To investigate the value of blood oxygen level-dependent (BOLD) and arterial spin labeling (ASL) MRI in the early diagnosis of renal allograft dysfunction. Methods A total of 53 patients with allograft kidney transplantation from December 2014 to April 2017 in Tianjin First Center Hospital were prospectively collected. In all cases, the serum creatinine value was detected, and the estimated glomerular filtration rate (eGFR) was calculated. All patients were divided into three groups according to the eGFR. There were three groups;continuous renal transplant function group (group A, 19 cases), short term allograft dysfunction group (group B, 17 cases), and continuous renal function damage group (group C, 17 cases). Fifty-three patients were examined by BOLD and ASL MRI at 10 to 14 days after operation. Twenty one patients were reviewed by BOLD and ASL MRI at 10 to 13 weeks after operation (A, B and C group were 7, 6, 8 cases). The values of renal cortex R2* (R2*=1/T2*), renal medullary R2* and renal cortical renal blood flow (RBF) were measured in each group. One-way analysis of variance (ANOVA) was used to compare the differences of eGFR and BOLD, ASL index (renal cortex R2*, renal medulla R2*, renal cortex RBF value) after the first post renal transplant among the 3 groups. Correlations between BOLD and ASL index with eGFR index in the first post renal transplant were assessed by using Pearson correlation analysis. The efficacy of BOLD and ASL in the differential diagnosis of continuous renal transplant function group and short term allograft dysfunction group by the receiver operating characteristic (ROC). Paired samples t test was used to compare the differences of eGFR, BOLD and ASL indexes for the baseline and follow-up. Results The differences of eGFR, cortical R2*value, medullary R2*value and cortical RBF value were statistically significant between the 3 groups (P<0.05). The transplanted kidney medullary R2* value and cortical RBF value were positively correlated with eGFR (r values were 0.553, 0.687; P<0.01). There was no correlation between transplanted kidney renal cortex R2*value and eGFR value (P>0.05). The area under ROC was 0.776 for the renal medullary R2*in the diagnosis of continuous renal transplant function group and the short term allograft dysfunction group;with the threshold of 24.5, the sensitivity of diagnosis of renal allograft short term allograft dysfunction was 58.8%, specificity was 84.2%;the area under ROC for renal cortex RBF was 0.881, with the threshold of less than 277 ml·100 g-1·min-1, the sensitivity was 70.6%, specificity was 89.4%. During follow-up, eGFR, cortical R2*and medullary R2*in group A remained stable, while the renal cortex RBF value went slightly higher, and the differences were statistically significant ( P<0.05). The cortical R2* values in group B remained stable, eGFR, renal medulla R2* and renal cortex RBF decreased, and the differences were statistically significant (P<0.05). The values of eGFR and R2*in group C remained stable, while the renal medullary R2* value and cortex R2* value increased slightly, and the differences were statistically significant (P<0.05). Conclusions This study shows that BOLD and ASL MRI can longitudinally monitor the functional status of the transplanted kidney and detect the abnormality of renal allograft function early. CRBF value shows high diagnostic value.