磁共振功能成像方法评价狼疮肾炎的肾损害

Functional MR imaging of kidneys in patients with lupus nephritis

目的探讨磁共振（MR）功能成像方法在评价狼疮肾炎（LN）。肾损害程度和反映肾脏病理改变方面的价值。方法LN患者17例使用GE3．0T磁共振扫描仪、TorsoPA相控阵线圈，进行肾脏冠状面T1WI、T2WI、DWI及BOLD成像。用Functool软件测量肾脏的表观扩散系数（ADC）和表观自旋-自旋弛豫率（R^2＊）值。10例志愿者作为正常对照。分析LN患者的ADC和R^2＊值与临床指标和病理改变的关系。结果LN肾脏ADC值为（2．43±0．24）×10^-3mm2／s，皮、髓质R^2＊值分别为（11．72±2．35）／s和（13．07±2．35）／s，均显著低于正常肾脏测值（分别P=0．045，P=-0．048和P=0．001）。LN肾脏ADC值与eGFR显著相关（r=0．558，P〈0．05），右。肾ADC值与LN肾脏病理慢性指数呈负相关（r=-0．493，P〈0．05）。髓质R^2＊值与24h尿蛋白量、血肌酐、肾脏病理活动指数、肾小球病变和肾小管间质病变均呈负相关。将17例患者分为A组（Ⅲ、Ⅳ、Ⅴ型）8例和B组（Ⅴ＋Ⅲ和Ⅴ＋Ⅳ型）9例，B组肾小管功能损害较A组重，B组ADC值和皮质R^2＊值低于A组，髓质R^2＊值与A组差异无统计学意义。结论功能性MR检查显示LN肾脏ADC值和皮、髓质R^2＊值均显著低于正常肾脏，且与血肌酐、24h尿蛋白量和肾小管功能、肾组织病理改变呈一定的相关性。DWI成像和BOLD成像检查为动态监测LN肾功能损害和。肾组织病理改变提供了一种无创性方法，可能为临床干预的疗效评价提供依据。

Objective To evaluate the functional magnetic resonance （MR） imaging in the assessment of renal involvement and pathological changes in patients with lupus nephritis （LN）. Methods Seventeen patients with LN and 10 healthy controls underwent coronal echo- planar diffusion- weighted （DW） MR imaging and blood oxygen level dependent （BOLD） MR imaging of the kidneys with a single breath- hold time of 16 s. The apparent diffusion coefficient （ADC） and R2. value of the kidneys were calculated with high b values （b=500 s/mm2）. The correlation between the renal injury variables and the ADCs or R2. values was evaluated. Results The mean ADC value of kidneys in patients with LN was （2.43±0.24）×10^-3 mm2/s, the mean R2. values of the renal cortex and medulla were （11.72±2.35）/s and （13.07±2.35）/s respectively, which were all significantly lower than those in volunteers （p=0.045, P=0.048 and p=0.001, respectively）. In the patients with LN, the mean ADC values were positively correlated with estimated glomerular filtration rate （eGFR） （r=0.558,p〈0.05）. There was a negative correlation between the ADC values Of the right kidneys and pathological chronic indexes （r=-0.493, p〈0.05）. Moreover, the R2＊values of the renal medulla were negatively correlated with 24 hours proteinuria, serum creatinine, pathological active indexes. The patients were assigned to group A （class Ⅲ、Ⅳ、Ⅴ, n=8） and group B（class Ⅲ、Ⅲ and Ⅴ ＋ Ⅳ, n=9）. The tubulointerstitial lesions in group B were more severe than those in group A, while the mean ADC values and R2. values of the renal cortex in group B were lower as compared to group A. Conclusion DW MR imaging and BOLD MR imaging may be used to non- invasively monitor the disease activity and evaluate the efficacy in lupus nephritis.