To investigate the effects of diffusion-weighted MRI (DW-MRI) on the evaluation of renal function in children with chronic kidney disease (CKD) by the apparent diffusion coefficient (ADC).

A total of 77 children with CKD who were admitted to West China Second Hospital, Sichuan University from January 2014 to June 2017 were recruited as research subjects in case group. According to the CKD staging of children, subjects in case group were further divided into CKD 1-2 stage subgroup (n=60) and CKD 3-5 stage subgroup (n=17). A total of 16 healthy children volunteers recruited in the same hospital during the same period were selected in control group. DW-MRI was used to detect the ADC values of bilaterally renal cortex and medulla of all subjects. Meanwhile, serum creatinine concentrations and estimated glomerular filtration rate (eGFR) were measured within 1 month before DW-MRI examination in all subjects. Independent-samples t test was used compare the ADC values of bilaterally renal cortex and medulla between case group and control group, and paired-samples t test was used to compare within the group. One-way ANOVA analysis was used to compare the ADC values of bilaterally renal cortex and medulla in CKD 1-2 stage subgroup, CKD 3-5 stage subgroup and control group, and the Bonferroni method was used for further comparison between each two groups. Pearson correlation analysis was conducted to analyze the correlation between ADC values of bilaterally renal cortex, medulla and eGFR, serum creatinine concentration in children with CKD. This study was approved by the Ethics Committee of Human Beings in West China Second University Hospital, Sichuan University (approval No. 2014081). The guardians of every subject obtained informed consent and signed informed consent form before MRI examination. There were no statistical differences between two groups in the aspects of gender ratio and age (P=0.785, 0.980).

①There were no significant differences in the ADC values of left and right renal cortex, and the ADC values of left and right renal medulla of case group (P>0.05). There were no significant differences in the ADC values of left and right renal cortex, and the ADC values of left and right renal medulla of control group (P>0.05). ②The ADC values of bilaterally renal cortex and medulla in the CKD 1-2 stage subgroup were (2.22±0.09) × 10^-3 m²/s and (1.97±0.11) × 10^-3 m²/s, respectively, and (2.02±0.16) × 10^-3 m²/s, (1.72±0.14) × 10^-3 m²/s, respectively in CKD 3-5 stage subgroup, and (2.35±0.06) × 10^-3 m²/s, (2.09±0.09) ×10^-3 m²/s, respectively in control group. There were significant differences in the ADC values of bilaterally renal cortex and medulla among above three groups (F=42.942, 48.956; P<0.001). Further comparison results showed that there were statistical differences between any two groups out of the above three groups in the cortex and medulla ADC values (P<0.001). ③In case group, there were linear positive correlations between ADC values of bilaterally renal cortex, medulla and eGFR (r=0.621, 0.657; P<0.001), and there were linear negative correlations between ADC values of bilaterally renal cortex, medulla and serum creatinine concentrations (r=-0.708, -0.681; P<0.001).

In our study, DW-MRI is considered to be an effective method to evaluate renal functions of children with CKD. The ADC value can reflect the children′s renal functions. In addition, the ADC value can provide a reference for clinical judgment of healthy children, children with mild CKD and children with moderate to severe CKD. However, whether there is prospect for application of CKD renal functions assessment in children by DW-MRI, large-sample, multi-center randomized controlled trials are needed for further study and confirmation.