血氧水平依赖磁共振成像评估急性马兜铃酸肾病大鼠肾脏氧合水平变化

Evaluation of renal oxygenation in rats with acute aristolochic acid nephropathy using blood oxygenation level-dependent magnetic resonance imaging

目的利用7.0T小动物磁共振行血氧水平依赖(BOLD)磁共振成像(MRI)技术评估急性马兜铃酸肾病(AAN)大鼠肾脏氧合水平变化。方法 AAN组大鼠(n=18)连续6 d腹腔注射马兜铃酸I型溶液,剂量为40 mg/(kg·d),随机选取6只大鼠于注药前及注药后2、4、6 d进行BOLD MRI扫描,测量大鼠肾脏皮髓质的R2~*值,于上述时间点分别处死3只大鼠行肾脏病理检查。对照组(n=6)连续6 d腹腔注射PEG400溶液,磁共振扫描方案同AAN组大鼠,于注药后第6天处死3只大鼠行肾脏病理检查。结果第4天及第6天AAN组皮质及髓质R2~*值较对照组均升高(P<0.05)。AAN组皮质R2~*值第4天(P<0.05)及第6天(P<0.01)较注药前上升;AAN组髓质R2~*值随时间呈逐渐升高趋势,第2天R2~*值较注药前无统计学差异,第4天R2~*值继续升高(P<0.01),第6天显著高于注药前(P<0.05)。对照组各个时间点皮质及髓质R2~*值较注药前均无统计学差异。结论 BOLD MRI能够无创评估急性AAN大鼠肾脏氧合水平变化,随着AAN大鼠肾脏损伤的进展,定量参数R2~*值升高提示肾脏氧合水平降低,尤其是髓质,从而为临床治疗决策提供重要信息。

Objective To evaluate the changes in renal oxygenation in rats with acute aristolochic acid nephropathy using blood oxygenation level-dependent(BOLD)magnetic resonance imaging(MRI)at 7.0 T.Methods Wistar rats were randomly divided into AAN group(n=18)and control group(n=6)for intraperitoneal injections of AAI at 40 mg/kg and PEG400,respectively,on a daily basis for 6 consecutive days.All the control rats and 6 rats from AAN group underwent BOLD MRI scan before and at2,4,and 6 days after the initial injection for measuring renal cortical and medullary R2~*values.At each of the 4 time points,3 rats in AAN group were sacrificed for histological evaluation;the control rats were examined at 6 days after the initial injection.Results The cortical and medullary R2~*values of the rats in AAN group on days 4 and 6 were significantly higher than those in the control group(P<0.05).In AAN group,the cortical R2~*values showed no obvious changes on day 2 as compared with the baseline values,but increased significantly on day 4(P<0.05)and day 6(P<0.01);the medullary R2~*values increased progressively and were significantly higher than the baseline values on day 4(P<0.01)and day 6(P<0.01).In the control group,no significant changes were detected in either cortical or medullary R2~*values throughout the experiment.Conclusion BOLD MRI allows non-invasive measurement of renal oxygenation levels in rats with AAN.The increase of renal cortical and medullary R2~*values,and particularly the latter,indicates a lowered renal oxygenation level,which provides potentially useful information for clinical decisions.