动态增强MRI测量猪单侧肾功能不全模型肾小球滤过率

目的探讨使用小剂量Gd-DTPA动态增强MRI并利用Patlak曲线法计算猪单侧肾功能不全肾脏及正常肾脏肾小球滤过率(glomerular filtration rate,GFR)的准确性。方法通过外科手术建立5只猪左侧肾动脉狭窄模型及5只猪左侧输尿管不全梗阻模型。使用3.0T MR机行小剂量Gd-DTPA(0.04mmol/kg)冠状面动态增强MR检查,随即进行99Tcm-DTPA动态核素肾图检查。在工作站上描绘双侧肾皮质时间-信号强度曲线(即MR肾图),根据MR肾图使用Patlak公式计算GFR。采用Pearson相关分析、Bland-Altman分析和组内相关系数评价MR肾图与核素肾图GFR计算结果的一致性。结果全部10只猪共20侧肾脏GFRMR平均为(39.60±12.42)ml/min(7.62～66.40ml/min),GFRSPECT平均值为(40.72±15.27)ml/min(7.60～74.90ml/min),GFRMR与GFRSPECT呈显著相关(r=0.836,P=0.000)。GFRMR与GFRSPECT平均差值为-1.11ml/min,95%一致性界限为-17.46～15.24ml/min之间,所有20侧肾脏GFR差值均位于该范围;组内相关系数为0.9508(P0.01),以上一致性检验结果均表明GFRMR与GFRSPECT一致性很好。结论利用小剂量Gd-DTPA动态增强MR检查可获得GFR,与99Tcm-DTPA肾动态显像测量的GFR具有较好的相关性及一致性。

Measurement of unilateral glomerular filtration rate with dynamic contrast-enhanced MRI in swine renal dysfunctional model

Objective:To investigate the accuracy in estimating single kidney glomerular filtration rate(GFR) derived from low dose dynamic contrast-enhanced MR(MR Renography,MRR) and Patlak model in swine with unilateral renal arterial stenosis(RAS) and hydronephrosis on 3.0 T.Materials and Methods:In this animal care and use committee-approved study,RAS was surgically created in five pigs and hydronephrosis was surgically induced in another five pigs.Dynamic low-dose gadopentetate dimeglumine(0.04 mmol/kg) contrast enhanced MR imaging was performed in all ten pigs with a 3.0 T scanner.99Tcm-DTPA scintigraphy soon afterwards provided reference standard of single-kidney GFR.Average signal intensities(SI) of region of interest on bilateral renal cortex were measured for each series,relative SI increments were calculated and the time-SI curves were plotted.Patlak model was used to analyze the aortic and renal cortical signal intensity vs.time curves(MRR) to obtain split GFRs.Values were reported as mean ± standard deviation(SD).GFRs measured with MRR were compared with the reference value from scintigraphy using Pearson’s correlation coefficient.The agreements between the two methods were assessed with the Bland-Altman plots and intraclass correlation coefficients(ICC),respectively.Results:Unilateral GFR from MR renography derived from Patlak model agreed well with reference measurements [(40.72±15.27) ml/min,7.60-74.90 ml/min] in cortex regions [(39.60±12.42) ml/min,7.62-66.40 ml/min)](r =0.836,P = 0.000,n=20).Bland-Altman analysis showed that the average difference between GFRMR and reference values was-1.11 ml/min with a 95% confidence interval from-17.46 ml/min to 15.24 ml/min,of all 20 coupled GFRs,differences were within range of 95% confidence interval.The ICC value was 0.9508(P<0.01).There statistical analysis showed there was a good consistence between GFRMR and standard reference.Conclusions:GFRs could be measured with low-dose MR renography and Patlak model,it has good consistence with standard reference from 99Tcm-DTPA scintigraphy.