磁敏感加权成像评价慢性肾功能损伤的价值

Susceptibility-weighted imaging for the assessment of chronic renal injury

目的 探讨磁敏感加权成像（SWI）评价慢性肾功能损伤的价值.方法 回顾性分析临床诊断为慢性肾功能损伤,且进行过肾脏常规MRI和SWI检查的39例患者的临床资料.根据估算肾小球滤过率（eGFR）将患者分为轻度损伤组（15例）和中重度损伤组（24例）.同期招募无慢性肾病史且血清肌酐及尿素氮指标正常的17名志愿者作为对照组.所有受试者均行肾脏常规MRI和SWI检查.测量计算双肾幅度图皮质/髓质值（C/MMAG）及磁敏感图皮质/髓质值（C/MSWI）.采用独立样本t检验比较对照组与肾功能损伤组间C/MMAG和C/MSWI的差异,配对样本t检验比较C/MMAG和C/MSWI间的差异,单因素方差分析比较对照组和不同肾功能损伤组间C/MMAG和C/MSWI的差异;采用ROC评价C/MMAG和C/MSWI诊断肾功能损伤的效能;采用Pearson线性相关分析评价肾功能损伤患者C/MMAG和C/MSWI与eGFR及血清肌酐水平的相关性.结果 肾功能损伤组的C/MMAG和C/MSWI分别为1.101±0.039、1.071±0.046,C/MSWI明显低于C/MMAG,差异有统计学意义（t=5.056,P＜0.01）.对照组的C/MMAG与C/MSWI间差异无统计学意义（P＞0.05）.肾功能损伤组的C/MMAG和C/MSWI均明显低于对照组,差异均有统计学意义（t值分别为4.564、6.122,P均＜0.01）.轻度损伤组和中重度损伤组的C/MMAG、C/MSWI均较对照组明显减低,差异有统计学意义（P均＜0.05）;轻度损伤组和中重度损伤组间的C/MMAG、C/MSWI差异均无统计学意义（P均＞0.05）.C/MMAG及C/MSWI诊断肾功能损伤的ROC下面积分别为0.853和0.952.C/MMAG与eGFR呈中度正相关（r=0.460,P＜0.01）.结论 SWI可用于预测慢性肾功能损伤,虽不能反映肾功能损伤的程度,但对早期诊断轻度肾损害有一定价值.

Objective To explore the value of susceptibility-weighted imaging （SWI） for the assessment of chronic renal injury. Methods Thirty-nine patients with clinical diagnosis of chronic renal injury （RI group） who underwent routine renal MRI and SWI examination were retrospectively analyzed. They were divided into mild injured group （15 cases） and moderate to severe injured group （24 cases） by estimated glomerular filtration rate （eGFR）. At the same time, 17 volunteers without chronic renal injury who had normal serum creatinine （Scr） and blood urea nitrogen were recruited as control group. All subjects underwent routine renal MRI and SWI examination. The ratios of cortex to medulla were measured and calculated in both kidneys＆#39; magnitude image and susceptibility weighted image, which were indicated as C/MMAG and C/MSWI. Independent sample t test was used to compare the differences of C/MMAG and C/MSWI between control group and RI group, and paired sample t test was used to compare the differences betweenC/MMAG and C/MSWI in each group. One-way ANOVA was used to compare the difference of C/MMAG and C/MSWI between the control group and the different RI groups. ROC was employed to assess the diagnostic efficacy of C/MMAG and C/MSWI in renal injury. Pearson linear correlation analysis was used to evaluate the correlation between C/MMAG, C/MSWI and eGFR, Scr in patients with renal injury. Results The C/MMAG and C/MSWI in the RI group were 1.101±0.039 and 1.071±0.046, respectively. C/MSWI was obviously lower than C/MMAG, and the difference was statistically significant （t=5.056, P〈0.01）. There was no significant difference between C/MMAG and C/MSWI in the control group （P〉0.05）. The C/MMAG and C/MSWI in the RI group were obviously lower than those in the control group, and the difference was statistically significant （t=4.564, 6.122;P〈0.01）.The C/MMAG and C/MSWI in the mild injured group and the moderate to severe injured group were significantly lower than those in the control group, the difference was statistically significant （P〈0.05）. While the differences of those between mild injured group and moderate to severe injured group showed no statistical significance （P〉0.05）. The area under ROC of C/MMAG and C/MSWI in diagnosis of renal injury were 0.853 and 0.952, respectively. C/MMAG was positively correlated with eGFR （r=0.460,P〈0.01）. Conclusions Susceptibility-weighted imaging can be used to assess chronic renal injury. Although it cannot reflect the degree of renal function damage, it has some value in the early diagnosis of mild renal injury.