Peters A M, George P, Ballardie F, Gordon I, Todd-Pokropek A
Department of Diagnostic Radiology, Hammersmith Hospital, London, UK.
Nucl Med Commun. 1988 Dec;9(12):973-85. doi: 10.1097/00006231-198812000-00006.
Since 99Tcm-DTPA is diffusible and not significantly protein bound in plasma, it rapidly enters the extravascular space following injection. Therefore, during the first few minutes of the DTPA renogram, the period on which the measurements of individual kidney glomerular filtration rate and differential function are based, background activity comprises a rising extravascular signal and a falling intravascular signal. The aim of this study was to measure the ratio of these two signals in background present within the renal region of interest (ROI) and compare it with the ratio in a background ROI. An appropriate background ROI is one in which the ratio is equal to that in background in the renal ROI. To pursue this aim, we quantified the rates of change of the intravascular and extravascular activities in background and, by comparing them with the rate of increase of filtered activity, expressed them as GFR equivalents (the intravascular being negative). It is impossible, from a single renogram, to separate the rising extravascular signal from the signal due to filtered activity, and therefore impossible to quantify the extravascular GFR equivalent present in background within the renal ROI. We therefore studied six patients undergoing bone marrow transplantation before and after cyclosporin treatment. By comparing the dynamic renographic data between the two sequential studies, the substantial fall in GFR (from 107 +/- 12 S.D. to 49 +/- 7 ml min-1) permitted separate quantification of the extravascular GFR equivalent in the renal ROI in both studies. Three of the patients were studied on a third occasion after cyclosporin. In two, GFR remained low and these studies were paired with corresponding baseline studies, while in the other it increased and this was compared with the nephrotoxic study, giving a total of nine paired studies between which GFR changed. The ratio of intravascular to extravascular GFR equivalents in a background ROI placed above the kidney was considerably greater, and in a background ROI below the kidney considerably less, than that in the renal ROI. A background ROI which was the difference between the renal ROI and a perirenal ROI, 2 pixels outside the renal ROI along the horizontal and 1 pixel outside along the vertical, gave a ratio almost identical to that of the background within the renal ROI (renal ROI ratio:background ROI ratio = 1.09 +/- 0.17 S.D., n = 18).(ABSTRACT TRUNCATED AT 400 WORDS)
由于99锝-二乙三胺五醋酸（99Tcm-DTPA）具有扩散性且在血浆中与蛋白质结合不显著，注射后它会迅速进入血管外间隙。因此，在DTPA肾图的最初几分钟内，即基于个体肾脏肾小球滤过率和分肾功能测量的时间段，本底活性包括上升的血管外信号和下降的血管内信号。本研究的目的是测量感兴趣肾区（ROI）内本底中这两个信号的比值，并将其与本底ROI中的比值进行比较。合适的本底ROI是指其比值与肾ROI中的本底比值相等的ROI。为实现这一目标，我们对本底中血管内和血管外活性的变化率进行了量化，并通过将它们与滤过活性的增加率进行比较，将它们表示为肾小球滤过率（GFR）当量（血管内为负值）。从单次肾图中，无法将上升的血管外信号与滤过活性产生的信号区分开来，因此无法量化肾ROI内本底中存在的血管外GFR当量。因此，我们研究了6例接受环孢素治疗前后的骨髓移植患者。通过比较两次连续研究之间的动态肾图数据，GFR的大幅下降（从107±12标准差降至49±7 ml/min）使得在两项研究中都能够分别量化肾ROI中的血管外GFR当量。其中3例患者在环孢素治疗后又进行了第三次研究。在2例患者中，GFR仍保持较低水平，这些研究与相应的基线研究配对，而在另一例患者中GFR升高，并将其与肾毒性研究进行比较，总共得到9对GFR发生变化的配对研究。位于肾脏上方的本底ROI中血管内与血管外GFR当量的比值明显更大，而位于肾脏下方的本底ROI中该比值明显更小，均低于肾ROI中的比值。一个由肾ROI与肾周ROI之差构成的本底ROI（在水平方向上位于肾ROI外2个像素，垂直方向上位于肾ROI外1个像素）给出的比值几乎与肾ROI内的本底比值相同（肾ROI比值：本底ROI比值 = 1.09±0.17标准差，n = 18）。（摘要截短于400字）
