Gates法测定肾小球滤过率的精确性及与病理对照分析

目的 探讨Gates法测定GFR的精确性,及其与肾病理改变之间的相互关系,获得Gates法测定GFR的适用范围.方法 选取99Tcm-DTPA肾功能曲线中双肾均无明显b段（即无超滤液形成段,A组）及双肾均有明显b段（B组）肾病患者各27例,比较Gates法测定GFR与CockcroftGault（C-G）公式、肾病膳食改良试验（MDRD）方程评估GFR及SCr之间的相关性,2组间病理结果（肾小球硬化分数和肾小管间质病变分数）差异行t检验比较.结果 线性相关分析证实：A组中,Gates法测定的GFR与C-G公式、1/SCr之间无明显相关性（r=0.357,0.376,P均＞0.05）与MDRD方程估算的GFR有明显相关性（r=0.440,P＜0.05）;B组中,Gates法测定的GFR与C-G公式、MDRD方程估算的GFR及1/SCr之间有正相关性（r=0.471,0.527,0.452,P均＜0.05）.A组肾小球硬化分数与B组差异无统计学意义,分别为0.26±0.24,0.27±0.21（t=-0.146,P＞0.05）,A组肾小管间质病变分数与B组差异有统计学意义,且较B组严重,分别为7.15±2.32,3.70±3.06（t=4.663,P＜0.001）.结论 99Tcm-DTPA肾功能曲线中双肾均无明显b段时,Gates法测定GFR的精确度明显低于双肾有明显b段者;99Tcm-DTPA肾功能曲线中双肾无明显b段与肾小管间质严重病变相关.     

兴趣区设置对Gates法测定肾小球滤过率的影响

目的:探讨肾脏及本底兴趣区ROI的勾画方式对Gates法测定肾小球滤过率(GFR)的影响.方法:对41例患者行肾动态显像,并按不同ROI勾画法计算GFR.改变本底ROI位置、大小、本底与肾脏ROI距离及肾脏ROI大小、局部偏离,观察GFR变化;将各GFR与标准Gates法GFR比较,观察结果偏离程度及导致结果偏离的因素.结果:①logistic多因素分析表明,本底ROI位置、大小、本底与肾脏ROI间距离以及"肾脏ROI大小、局部偏离"均是影响GFR的重要因素(χ2分别为250.9,73.9,53.5,215.8,P=0.000);②本底位于肾脏正下方较大范围内或肾脏ROI在外下方局部外偏时GFR与标准Gates法十分接近;本底ROI、肾脏ROI的其它各种改变均可对GFR产生较大程度的影响.结论:①Gates法GFR测定时,ROI勾画须注意多种影响因素的作用.②本底ROI设置于肾脏正下方(20～160)象素大小、(0～16)象素距离范围内可减少本底大小、距离对GFR影响.     

Gates法测定2型糖尿病肾病患者肾小球滤过率

目的 探讨2型糖尿病肾病患者99Tcm-DTPA GFR测定的时间影响及GFR对2型糖尿病肾功能异常早期诊断的临床意义.方法 招募健康志愿者11名,其中男6名,女5名,年龄47～79(61.45±7.90)岁;社区2型糖尿病肾病患者56例,其中男31例,女25例,年龄45～75(60.98±6.96)岁,均应用99Tcm-DTPA肾动态显像测定GFR.分别取注药后第2分钟和第3分钟图像勾画ROI,根据Gates分析方法,计算总肾及分肾GFR.利用SPSS 15.0软件对数据进行Pearson相关分析和两样本t检验.结果 2型糖尿病肾病患者的GFR与SCr[(84.90±14.38) μnol/L]呈负相关:注射99Tcm-DTPA后第2分钟双肾、左肾和右肾GFR均与SCr呈负相关(r=-0.599、-0.553和-0.529,均P＜0.001);第3分钟双肾、左肾和右肾GFR也均与SCr呈负相关(r=-0.652、-0.636和-0.470,均P≤0.001).2型糖尿病肾病患者双肾、左肾和右肾第3分钟GFR分别为(69.77±11.00)、(33.12±5.74)和(37.34±9.81) ml/min,低于健康对照组[(97.89±5.98)、(46.60±4.91)和(51.28±4.20) ml/min;t=-8.212、-7.233和-4.069,均P＜0.001].结论 建议对2型糖尿病肾病患者选择注射99Tcm-DTPA后第3分钟的放射性计数测定GFR;GFR测定对糖尿病肾病患者肾功能异常早期诊断具有重要意义.     

Gate's法测定肾小球滤过率及其影响因素

肾小球滤过率(GFR)是评估肾脏功能的重要指标,与其他测定方法相比,核医学肾动态显像Gate's法具有使用简便、结果准确的特点.影响该法检测结果的因素包括肾脏放射性计数、感兴趣区的勾画、肾脏深度等多种因素.     

Gate's法测定肾小球滤过率及其影响因素

肾小球滤过率(GFR)是评估肾脏功能的重要指标,与其他测定方法相比,核医学肾动态显像Gate's法具有使用简便、结果准确的特点.影响该法检测结果的因素包括肾脏放射性计数、感兴趣区的勾画、肾脏深度等多种因素.     

肾小球滤过率的标准化参数

GFR的标准化对非肿瘤患者,特别是肾供体较为重要.目前研究较多的GFR标准化参数有:体表面积(BSA)、细胞外液容积(ECV)和瘦体质量(LBM).BSA的准确测定较为困难,且儿童和肥胖者的标准化效能较差;ECV特别适用于健康儿童的标准化,但肾功能受损患者的临床应用价值明显减低;LBM兼具定量准确、适用范围广等优点,现有研究表明其比BSA和ECV更适用于GFR的标准化,但其影响因素尚待进一步深入研究.     

慢性肾脏病患者肾小球滤过率经验公式比较

目的比较肾脏疾病饮食改良研究方程式(MDRD)、新慢性肾脏疾病流行病学合作研究方程式(CKD-EPI)以及胱抑素C(Cys C)估算公式(eGFR-Cys)对慢性肾脏病(CKD)患者肾小球滤过率(GFR)的预测性能。方法测定93例CKD患者的99mTc-二乙烯三胺戊乙酸(DTPA)血浆清除率(rGFR)作为GFR金标准,另用MDRD、CKD-EPI和eGFR-Cys公式分别计算GFR估测值(eGFR),并将rGFR与3种公式计算的eGFR进行比较。结果相对于rGFR,CKD-EPI公式偏倚为-3.4±10.7ml/(min·1.73m2),eGFR-Cys公式为-4.8±11.9ml/(min·1.73m2),MDRD公式为-5.4±10.4ml/(min·1.73m2),三者间差异均无统计学意义。对于rGFR测定值30%误差范围内GFR估测值的百分率,CKD-EPI公式e、GFR-Cys公式、MDRD公式分别为74.2%7、2.0%和64.5%,差异无统计学意义。当rGFR>60ml/(min·1.73m2)时,CKD-EPI公式30%准确度(75.7%±5.1%)明显高于MDRD公式(54.1%±7.7%,P<0.05)。以放射性核素法的GFR作为标准,以rGFR≤60ml/(min·1.73m2)作为GFR受损标准,进行3种eGFR诊断GFR受损性能的受试者工作特征(ROC)曲线分析,MDRD eGFR的ROC曲线下面积为0.862,CKD-EPI为0.863,eGFR-Cys为0.877,3个曲线下面积的差异无统计学意义。结论 3个公式对GFR的估算能力基本相似。CKD-EPI公式和eGFR-Cys公式是否可以取代MDRD公式尚需进一步研究。     

Comparison of glomerular filtration rate by Gates method with Cockroft Gault equation in unilateral small kidney

Objective

To compare the glomerular filtration rate (GFR) by ^99mTc DTPA scan and the Cockroft Gault method in unilateral small kidney.

Materials and methods

The present study was conducted in the Department of Nuclear Medicine at the Sher-i-Kashmir Institute of Medical Sciences (SKIMS), India from July 2007 to April 2011. The present study included 47 patients with a diagnosis of unilateral small kidney on ultrasound. Out of 47 patients, 21 (44.7%) were males and 26 (55.3%) were females. Image processing was done using camera based methods. The GFR was automatically calculated by a software in a commercially available computer according to the Gates algorithm. The predicted creatinine clearance was calculated according to the Cockroft and Gault equation.

Results

Mean total GFR by DTPA Gates method was 73.6 ± 18.6 ml/min and by the Cockroft Gault (CG) method was 79.8 ± 32.2 ml/min. The difference was statistically insignificant indicating an agreement between both the methods in measuring GFR.

Conclusions

To discuss the advantages of isotopic renography, CG cannot give individual kidney GFR and so is not of much use in the unilateral small kidney wherein the main aim is to know the function of the individual kidneys. Furthermore because of low cost and less radiation burden, this test might be preferred for routine practice in nuclear medicine.     

Calculation of the renal perfusion and glomerular filtration rate from the renal impulse response obtained with MRI.

The aim of this study was to assess the importance of deconvolution for the calculation of renal perfusion and glomerular filtration rate (GFR) on the basis of concentration-time curves as measured with perfusion MRI. Six rabbits were scanned dynamically after injection of a gadolinium chelate. Concentration-time curves were generated by manually drawing regions of interest in the aorta and the renal cortex. To remove the dependency on the arterial input function, a regularized structured total least-squares deconvolution algorithm was used to calculate the renal impulse response. This curve was fitted by the sum of two gamma variate functions, corresponding to the passage of the contrast agent in the glomeruli and the proximal convoluted tubules. Tracer kinetics models were applied to these two functions to obtain the renal perfusion and GFR. For comparison, these two parameters were also calculated on the basis of the renal concentration-time curve before deconvolution. The renal perfusion values correlated well (r = 0.9, P = 0.014) with the values calculated by a validated upslope method. The GFR values correlated well (r = 0.9, P = 0.014) with the values obtained from the clearance of (51)Cr-EDTA. A comparison of the values obtained with and without deconvolution demonstrated the necessity of deconvolution.     

Determination of single-kidney glomerular filtration rate (GFR) with CT urography versus renal dynamic imaging Gates method

Objectives

To present a single-kidney CT-GFR measurement and compare it with the renal dynamic imaging Gates-GFR.

Materials and methods

Thirty-six patients with hydronephrosis referred for CT urography and 99mTc-DTPA renal dynamic imaging were prospectively included. Informed consent was obtained from all patients. The CT urography protocol included non-contrast, nephrographic, and excretory phase imaging. The total CT-GFR was calculated by dividing the CT number increments of the total urinary system between the nephrographic and excretory phase by the products of iodine concentration in the aorta and the elapsed time, then multiplied by (1- Haematocrit). The total CT-GFR was then split into single-kidney CT-GFR by a left and right kidney proportionality factor. The results were compared with single-kidney Gates-GFR by using paired t-test, correlation analysis, and Bland-Altman plots.

Results

Paired difference between single-kidney CT-GFR (45.02 ± 13.91) and single-kidney Gates-GFR (51.21 ± 14.76) was 6.19 ± 5.63 ml/min, p<0.001, demonstrating 12.1% systematic underestimation with ±11.03 ml/min (±21.5%) measurement deviation. A good correlation was revealed between both measurements (r=0.87, p<0.001).

Conclusion

The proposed single-kidney CT-GFR correlates and agrees well with the reference standard despite a systematic underestimation, therefore it could be a one-stop-shop for evaluating urinary tract morphology and split renal function.

Key points

? A new CT method can assess split renal function ? Only using images from CT urography and the value of haematocrit ? A one-stop-shop CT technique without additional radiation dose

     

肾脏常规皮质髓质CT平扫及增强扫描与肾功能的相关性研究

目的 探讨肾脏常规皮质、髓质CT平扫与增强扫描与肾小球滤过率(GFR)的关系.方法 回顾性分析35例单侧肾后性梗阻性肾积水患者16层螺旋CT平扫与增强皮质期影像.以SPECT的GFR为参考标准,将35例患者按照肾功能结果分为4组:正常组,轻、中、重度肾功能损害组.测量计算患肾肾皮、髓质增强程度及各项比值.采用单因素方差分析比较上述指标的差异,采用Pearson法与GFR进行相关性分析.结果 肾功能正常组及轻、中、重度受损组患肾肾皮质增强程度(CT皮增-CT皮平)分别为(154.98±28.70)、(122.67±39.32)、(81.30±32.94)和(57.60±23.49)HU、增强后患侧与健侧皮质的CT值比值(CT患皮/CT健皮)分别为0.97±0.09、0.79±0.18、0.64±0.24和0.51±0.13、患侧及健侧髓质的CT值比值(CT患髓/CT健髓)分别为0.98±0.26、0.89±0.18、0.86±0.31和0.75±0.28、患侧皮髓质CT值比值(CT患皮/CT患髓)分别为2.76±0.35、2.35±0.79、1.83±0.68和1.73±0.28、患侧皮髓质CT值比值与健侧皮髓质CT值比值之比[(CT患皮/CT患髓)/(CT健皮/CT健髓)]分别为1.00±0.28、0.89±0.34、0.75±0.17和0.69±0.14,差异有统计学意义(P<0.05).肾皮质CT值增强程度与GFR呈高度正相关(r=0.887,P<0.01),肾髓质CT值增强程度与GFR无相关性(r=0.203,P>0.05),患侧与健侧皮质增强CT比值与GFR呈高度正相关(r=0.872,P<0.01),患侧及健侧髓质增强CT比值与GFR呈中度正相关(r=0.504,P<0.01),患侧皮髓质增强CT值比值与GFR呈高度正相关(r=0.772,P<0.01),患侧皮髓质增强CT比值与健侧皮髓质增强CT比值之比与GFR呈中度正相关(r=0.663,P<0.01).以皮质期CT患皮/CT患髓高(≥2.60)、较高(2.20～2.59)、中(1.80～2.19)、低(<1.80)为判断肾功能正常、轻度损害、中度损害与重度损害的标准,对35例患肾功能SPECT结果对照,两种分组的符合率为80.0%.结论 GFR分级定量分析,不同GFR分组各肾皮质相关CT增强指标差异有统计学意义,且与GFR呈正相关,其中患侧皮髓质增强CT值比值适用于对单、双侧梗阻患者单肾功能进行评价,可对肾后性梗阻积水肾功能损害作出半定量诊断,相对于CT灌注简单方便,X线辐射剂量低.     

Relationship between the renal apparent diffusion coefficient and glomerular filtration rate: preliminary experience

PURPOSE: To investigate the relationship between ADC values measured by diffusion-weighted MRI (DWI) and the split glomerular filtration rate (GFR). MATERIALS AND METHODS: DWI (b = 0 and 500 seconds/mm(2)) was performed with a 1.5 T MR unit in 55 patients. The ADCs were calculated with ROIs positioned in the renal parenchyma, and the split GFRs were measured by (99)Tc(m)-DTPA scintigraphy using Gates' method. The 110 kidneys were divided into four groups: normal renal function (GFR 40 mL x minute(-1)), mild renal impairment (40 > GFR > or = 20 mL x minute(-1)), moderate renal impairment (20 > GFR > or = 10 mL x minute(-1)), and severe renal impairment (GFR < 10 mL x minute(-1)). The renal ADCs between four groups were statistically compared by analysis of variance (ANOVA), and the relationship between ADCs and GFR was examined using Pearson's correlation test. RESULTS: The mean renal ADCs of the four groups were 2.87 +/- 0.11, 2.55 +/- 0.17, 2.29 +/- 0.10, and 2.20 +/- 0.11 x 10(-3)mm(2)/second, respectively. There was a statistically significant difference in renal ADCs among the four groups (P < 0.001). There was a positive correlation between the ADCs and split GFR (r = 0.709). CONCLUSION: The ADCs were significantly lower in impaired kidneys than in normal kidneys, and there was a positive correlation between the ADCs and GFR.     

Measurement of glomerular filtration rate by low-dose iopromide plasma clearance

Purpose: 
Glomerular filtration rate (GFR) can be measured by iopromide plasma clearance. As an injection of 120 ml nonionic contrast medium is expensive and especially in patients with nephropathy potentially nephrotoxic, we investigated whether iopromide plasma clearance could be measured using a tenth of that dose as 'low-dose' clearance. Material and Methods: 
Fifty adult patients scheduled for CT were recruited. Iopromide 300 mg I/ml was used for GFR measurement. Prior to CT, low-dose clearance was measured by injecting 12 ml iopromide per 75 kg b.w. At 3, 4 and 5 h after injection, plasma samples were obtained and the iodine concentration was measured by X-ray fluorescence analysis. Immediately after the last blood sample, CT was again performed following injection of 120 ml iopromide per 75 kg b.w. A further 3 plasma samples were then obtained 3, 4, and 5 h after CT and used for the determination of high-dose clearance. Results: 
Low-dose clearance ranged from 20 ml/min to 141 ml/min (mean 78.3 ml/min). High-dose and low-dose clearance correlated excellently, with clearance (high-dose) = 1.4 + 0.994 clearance (low-dose); the correlation coefficient was r = 0.944, the standard deviation SD_xy= 9.3 ml/min. Conclusion: 
Plasma clearance of iopromide is dose-independent on use of iodine amounts of 3.6 g and 36 g I/75 kg b.w. The GFR can be determined by high-dose and low-dose iopromide plasma clearance with identical accuracy.     

99Tcm-DTPA肾动态显像测定肾小球滤过率的影响因素分析

肾小球滤过率(GFR)是反映肾功能的重要指标,利用99Tcm-二亚乙基三胺五乙酸(99Tcm-DTPA)进行肾动态显像检测GFR是目前临床最常用的方法,但测量过程中的一些可变因素和操作细节,如血浆蛋白结合、肾脏和本底感兴趣区勾画、肾脏深度、患者年龄及自身肾功能、患者准备情况和操作技术等,都可能对GFR的检测产生影响。该...