探讨MRI弥散加权成像(DW-MRI)的表观弥散系数(ADC)对慢性肾脏疾病(CKD)患儿肾功能的评估作用。

选择2014年1月至2017年6月，四川大学华西第二医院收治的77例CKD患儿为研究对象，纳入病例组。根据儿童CKD分期，进一步将病例组患儿分为CKD 1～2期亚组(n＝60)，CKD 3～5期亚组(n＝17)。将同期本院招募的16例健康儿童志愿者，纳入对照组。采用DW-MRI检测所有受试儿的双肾皮质、髓质ADC值。同时采集其接受DW-MRI检查前1个月内的血清肌酐浓度和肾小球滤过率估算值(eGFR)。病例组和对照组受试儿双肾皮质、髓质ADC值组间比较，采用成组t检验，组内比较采用配对t检验。采用方差分析对CKD 1～2期亚组、CKD 3～5期亚组及对照组3组患儿的双肾皮质、髓质ADC值进行比较，并采用Bonferroni法进一步进行两两比较。对CKD患儿双肾皮质、髓质ADC值与eGFR、血清肌酐浓度的相关性分析，采用Pearson相关性分析。本研究通过四川大学华西第二医院伦理委员会审查(审批文号：2014081)。对所有受试儿进行MRI检查前，均征得其监护人知情同意，并签署知情同意书。病例组和对照组受试儿性别构成比、年龄分别比较，差异均无统计学意义(P＝0.785、0.980)。

①病例组受试儿自身左、右肾皮质ADC值比较，以及左、右肾髓质ADC值比较，差异均无统计学意义(P>0.05)。对照组受试儿自身左、右肾皮质ADC值比较，以及左、右肾髓质ADC值比较，差异亦均无统计学意义(P>0.05)。②CKD 1～2期亚组受试儿双肾皮质、髓质ADC值分别为(2.22±0.09)×10^－3 m²/s、(1.97±0.11)×10^－3 m²/s，CKD 3～5期亚组分别为(2.02±0.16)×10^－3 m²/s、(1.72±0.14)×10^－3 m²/s，对照组分别为(2.35±0.06)×10^－3 m²/s、(2.09±0.09)×10^－3 m²/s。上述3组受试儿双肾皮质、髓质ADC值分别整体比较，差异均有统计学意义(F＝42.942、48.956，P<0.001)。进一步对其进行两两比较的结果显示，上述3组受试儿任意2组的双肾皮质、髓质ADC值分别比较，差异均有统计意义(P<0.001)。③病例组CKD患儿中，双肾皮质、髓质ADC值与eGFR均呈线性正相关关系(r＝0.621、0.657，P<0.001)，与血清肌酐浓度均呈线性负相关关系(r＝－0.708、－0.681，P<0.001)。

本研究认为，DW-MRI是评估CKD患儿肾功能的有效方法。ADC值可反映儿童肾功能，并且ADC值可为临床判断健康儿童、轻度CKD和中、重度CKD患儿提供参考依据。但是，DW-MRI是否对CKD患儿肾功能评估具有应用前景，则尚需大样本、多中心随机对照试验进一步研究、证实。

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.