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.     

瘦体质量和体表面积校正肾小球滤过率的比较研究

目的:分析瘦体质量(lean body mass,LBM)是否较体表面积(body surface area,BSA)更适用于肾小球滤过率(glomerular filtration rate,GFR)的校正。方法:①将239例患者分为肾功能正常组(第1组)、轻度受损组(第2组)、中度受损组(第3组)和重度受损组(第4组),比较全部患者及每组患者的Gate’s法GFR(gGFR)与血浆法GFR(pGFR)的相关性,并分析线性回归方程意义。②将239例患者按照体质量指数分为超重组、正常组和过轻组,对比超重组和正常组、过轻组和正常组的pGFRlbm,分析体质量因素是否对LBM校正后的pGFR有影响。结果:①LBM校正后pGFR和gGFR的相关系数最高(P0.05);②全部患者、第1组~第4组LBM校正后较BSA校正后和未经校正后的截距更接近0,斜率更接近1,R2值最高;③pGFRlbm超重组和pGFRlbm正常组;pGFRlbm过轻组和pGFRlbm正常组差异均无统计学意义,故尚不能认为体质量会影响pGFRlbm,造成对pGFRlbm的高估或低估。结论:LBM较BSA能更好地校正GFR,是提高gGFR及pGFR相关性的很好选择。     

Gates法测定肾小球滤过率的精确性及与病理对照分析

Objective To evaluate the precision of GFR using Gates method and compared with the results from renal pathological changes. Methods Twenty-seven patients whose 99Tcm-DTPA renograms had no obvious uptake phase were enrolled in Group A, and 27 patients whose 99Tcm-DTPA renograms had obvious uptake phase were enrolled in Group B. The measurement of GFR by Gates method was compared to the creatinine clearance measured and predicted by Cockroft-Gault (C-G), modification of diet in renal disease (MDRD) and SCr level. Renal pathological changes in two groups were compared using Pearson correlation and t test analysis. Results In Group A, GFR determined by Gates method did not show correlation with that estimated by C-G or 1/SCr (r = 0. 357,0. 376, both P ＞0.05), but was significantly correlated with GFR estimated by MDRD(r = 0. 440, P ＜ 0.05). In Group B, GFR determined by Gates method showed significantly correlation among GFR estimated by MDRD, C-G, and 1/SCr (r =0. 471, 0. 527,0. 452, all P ＜ 0.05). Renal tubulointerstitial damage score in Group A was higher than that in Group B (7.15±2.32, 3.70±3.06, t=4.66, P ＜0.001). Conclusions GFR determined by Gates method is less precise when 99Tcm-DTPA renogram has no obvious uptake phase than that when 99Tcm-DTPA renogram has obvious uptake phase. Renal tubulointerstitial damage is a strong indicator of no obvious uptake phase in 99Tcm-DTPA renogram.     

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.     

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.     

Normalisation of glomerular filtration rate measurements

The result of a glomerular filtration rate (GFR) measurement on a particular patient is of limited use to the referring physician since normal GFR values vary widely with the patient's age and build, etc. To overcome this problem, it is usual to normalise the measured GFR by dividing it by the patient's surface area and multiplying the result by the surface area of a standard man. This transforms the measurement onto a scale which applies to all patients, young and old, large and small, where normal values fall within a well-defined range and where the degree of renal impairment can be quantified. We have examined the generally accepted surface area (SA) and the less well-known extracellular volume (ECV) normalisation methods of GFR measurements in a series of 110 patients. The results show that both methods produce essentially the same result; however, ECV normalisation is theoretically more correct, can be found directly without the patient's ECV being measured and does not require the use of empirical formulae. Mathematical justification for ECV normalisation is presented, and a proposed distribution pattern for the normalised measurement is introduced. A simple mathematical model shows that accurate GFR measurements can be made in the presence of an enlarged ECV, but normalisation of these will produce misleading low values.     

不同肾ROI勾画法对肾积水患者GFR测定影响的研究

目的：探讨不同肾ROI勾画法对肾积水患者肾小球滤过率（GFR）测定的影响。方法：对31例（39只积水肾）血清肌酐（SCr）升高的不同程度肾积水患者行肾动态显像,用Gates法分别按全肾ROI及肾皮质ROI计算GFR,并与同期检测的SCr进行相关性分析。结果：轻、重度肾积水患者,由两种ROI计算的GFR值均与SCr呈显著负相关,但全肾ROI的相关系数低于肾皮质ROI的相关系数;中度肾积水患者,全肾ROI测定的GFR与SCr无相关性,而肾皮质ROI测定的GFR则与SCr呈显著负相关。结论：肾皮质ROI勾画法更灵敏而准确的反映肾积水患者肾功能的变化。     

Effects of atrial natriuretic peptide on glomerular filtration rate in essential hypertension: a radionuclide study

A number of studies show that atrial natriuretic peptide (ANP) raises renal sodium excretion with a concomitant increase in glomerular filtration rate (GFR) in both experimental animals and normal humans. Studies using indirect evaluation of GFR have provided less consistent results in hypertensive patients. We studied the effects of intravenously administered (iv) -human ANP on GFR in patients with hypertension by a radionuclide technique using technetium 99m diethylenetriaminepenta-acetic acid. In six patients (ANP group), GFR was determined under control conditions, during iv ANP (initial bolus of 0.5 g/kg followed by a 21-min maintenance infusion at 0.05 g · kg^–1 · min^–1) and during a recovery phase. In six other patients (control group), GFR was determined under control conditions, during saline iv infusion and during recovery. The two groups did not differ with respect to age, sex, basal blood pressure, heart rate or GFR. In the ANP group, the infusion of the peptide induced a significant decrease of mean blood pressure (from 133 ± 5 to 120 ± 5 mmHg, P < 0.01), no change in heart rate and a significant increase in GFR (from 104 ± 4 to 125 ± 5 ml/min, P < 0.01). During recovery, blood pressure, heart rate and GFR were not different from the values recorded under control conditions. No changes in blood pressure, heart rate or GFR (from 106 ± 5 to 108 ± 5 ml/min, n.s.) were detected during saline infusion in the control group. Our results demonstrated that in patients with essential hypertension, ANP induces an augmentation in GFR in spite of a decrease in blood pressure; this suggests a unique role for atrial peptide-related drugs in the treatment of human hypertension.     

肾动态显像法与双血浆法在移植肾GFR测定中的对比

目的比较肾动态显像法与双血浆法测定的移植肾^99Tc^m-DTPA肾小球滤过率（dGFR和tGFR），以评价dGFR反映移植肾滤过功能的可靠性。方法选取73例肾移植患者，分别采用肾动态显像法和双血浆法测定其^99Tc^m-DTPA GFR。分析经体表面积标准化的dGFR与tGFR间的关系，并建立直线回归方程。结果dGFR均值略低于tGFR均值（t=-2．010，P〈0．05），dGFR与tGFR呈显著正相关（r=0．759，P〈0．01），直线回归方程：tGFR=0．6455XdGFR＋25．514。结论dGFR与tGFR具有较好的一致性，肾动态显像法能够准确评价移植肾的滤过功能。     

基于血清胱抑素C的肾功能估算公式在肾功能评价中的价值

目的以GFR为标准,评价基于血清胱抑素C的多种肾功能估算公式的价值。方法回顾性研究198例行^99Tc^m-DTPAGFR测定并有血清胱抑素C、SCr测定结果的住院患者（男85例,女113例,平均年龄66．5岁）。GFR测定采用Gates法,血清胱抑素C采用颗粒增强透射免疫比浊法测定,SCr采用苦味酸法测定。用8种不同的公式（6种基于血清胱抑素C,2种基于SCr）估算GFR,并与Gates法测得的GFR（实测值）比较（单因素方差分析和最小显著差异t检验）。根据实测GFR,将患者分为肾功能正常、轻度受损、中度受损和重度受损组。各公式法对肾功能损伤的诊断效能比较采用妒检验。结果198例中肾功能受损159例（轻度78例,中度58例,重度23例）。在肾功能中、重度受损者中,GFR[经体表面积（1．73m^-2）标准化,ml·min^-1]的Tan公式计算值与实测值差异均无统计学意义[重度：（20．7±7．4）ml·min^-1与（19．9±8．2）ml·min^-1,F=6．75,t〈1．05;中度：（42．1±14．4）ml·min^-1与（46．8±9．2）ml·min^-1,F=10．49,t〈1．63;均P〉0．05）,且其与实测值偏差最小[重度：（12．3±7．0）％;中度：（17．9±13．0）％]。肾功能轻度受损及肾功能正常者中,Tan公式无明显优势。基于SCr的简化肾脏病膳食改良研究（MDRD）公式和慢性肾脏病流行病学合作研究（CKD—EPI）公式诊断肾功能受损的灵敏度分别为66．0％（105／159）和70．4％（112／159）、准确性分别为71．2％（141／198）和73．7％（146／198）,低于基于血清胱抑素C的肾功能公式灵敏度[≥83．6％（133／159）]和准确性[≥79．3％（157／198）]x^2≥23．50,均P〈0．01。对于慢性肾病（中、重度肾损伤,81例）的诊断,基于血清胱抑素C的肾功能公式灵敏度[≥86．4％（70／81）]高于简化MDRD公式和CKD—EPI公式[分别为76．5％（62／81）和79．0％（64／81）],准确性[Tan公式,80．3％（159／198）]略下降（x^2≥56．42,均P〈0．05）。结论基于血清胱抑素C的Tan公式对肾功能中、重度受损（血清胱抑素C≥1．55mg／L）的判断优于简化MDRD公式和CKD-EPI公式,但对肾功能轻度受损及肾功能正常者价值不大。     

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.     

Estimation of glomerular filtration rate using 99mTc-DTPA and the gamma camera

Two methods of glomerular filtration rate estimation have been evaluated, based on the intravenous administration of ^99mTc-DTPA and the measurement of renal time activity curves by means of a computer linked gamma camera. A single 20 min plasma sample was also required. These methods were designed to minimize the component of error arising from decay statistics. One method was based on using a constant fraction of the cardiac activity in lieu of a perirenal region of interest for the background correction, the other was based on deconvolution by a constrained least squares technique. The first method, based on modifying the background correction, led to poor results (residual standard deviation 18.9 ml/min when compared with the plasma clearance method). The second method, based on constrained least squares deconvolution, worked as well as previously reported methods (residual standard deviation 14.5 ml/min) and appears suitable for clinical use.     

Measurement of glomerular filtration rate with 99mTc-DTPA: A comparison of gamma camera methods

A comparison has been made between three gamma camera methods for estimation of glomerular filtration rate (GFR) using ^99mTc-DTPA in a group of 27 patients with widely different renal function. Plasma clearance of ^99mTc-DTPA by multiple blood sampling was used as the reference. Percentage uptake of chelate in the bladder and kidneys at 20 min after injection gave the lowest standard error of 8.0 ml/min. Techniques using early uptake of isotope in the kidneys at 2 min after injection gave less accurate estimates. Correction for the vascular activity in the renal region of interest improved the results for the 2 min uptake technique. Gamma camera techniques provide rapid estimates of GFR which are less accurate than those obtained by plasma clearance of labelled chelate.     

The kinetic basis of glomerular filtration rate measurement and new concepts of indexation to body size

As measurement of glomerular filtration rate (GFR) is now generally the responsibility of departments of nuclear medicine, it is important for nuclear medicine physicians and scientists to understand the pharmacokinetics of the indicators and radiotracers that are used, generally known as filtration markers. The single-injection, non-steady state technique is almost universally used, departments varying in how many blood samples are taken: rarely multisample clearance, which does not assume a single compartment of tracer distribution, commonly clearance based on a limited number of blood samples between 2 and 4 h after injection, which assumes a single compartment of distribution, and often a single sample at a defined time point. The volume of distribution, V _d , of a filtration marker is close to extracellular fluid volume (ECFV). GFR and ECFV are both overestimated by the assumption of a single compartment by amounts that are functions of the rate of plasma clearance, Z. Residence time, T, of tracer in its V _d is equal to V _d divided by Z. Z and T can both be measured from a multisample clearance curve, whereupon V _d is the product of Z and T. GFR is usually indexed to patient size by expressing it in relation to body surface area (BSA), which in turn is calculated from an equation based on the patients height and weight. An equation in common use was described by Haycock et al. and is BSA=0.024265×weight^0.5378×height^0.3964. An alternative indexation variable is ECFV. GFR per unit ECFV is close to the rate constant, ₃, of the terminal exponential of the plasma clearance curve. It is in fact slightly higher than this rate constant by an amount that is a function of the rate constant itself. The discrepancy between GFR/ECFV and ₃ arises from the development of a concentration gradient between interstitial fluid and plasma, which in turn produces an extrarenal veno-arterial gradient throughout the body. Indexing GFR to ECFV not only has physiological attractions (especially in children) but is technically simple because it requires measurement only of ₃ (slope-only technique). A disadvantage, however, is a lack of robustness in comparison with the conventional slope/intercept method, which measures tracer dilution as well as ₃. Nevertheless, the advantages of indexation to ECFV can still be exploited by changing the constants of an equation of the Haycock type so that the equation becomes a predictor of ECFV rather than BSA. A recently described equation is ECFV=0.02154×weight^0.6469×height^0.7236. Indexation to ECFV abolishes differences that arise between children and adults when GFR is indexed to BSA.