动态增强MRI测量猪单侧肾功能不全模型肾小球滤过率

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

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(P<0.01),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。

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. ^99Tc^m-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-S1 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 ^99Tc^m-DTPA scintigraphy.