Nuclear Medicine Department, Royal Preston Hospital, Lancashire Teaching Hospitals NHS Trust, Preston, PR2 9HT, UK.
World J Urol. 2011 Feb;29(1):109-14. doi: 10.1007/s00345-010-0569-8. Epub 2010 May 29.
In acute unilateral renal obstruction, calculated divided renal uptake following injection of tracer may be normal. Divided renal function as measured by uptake may be insensitive to fall in renal plasma flow (RPF) to the obstructed kidney. This study analyses afferent flow rate parameters of optimised models of renogram time activity curves (TAC). Afferent flow rate parameters may have differing sensitivity to altered RPF from divided renal tracer uptake and may be more sensitive to changes in cortical function in renal obstruction.
Twenty-four background-corrected renogram TACs using 99mTc-labelled mercapto-acetyl-triglycine (MAG3) with a unilateral obstructive pattern and six normal control renograms TACs were studied. Optimised computed models of each curve were constructed using specialised software (ModelMaker, Cherwell Scientific) and using the Marquardt Least Squares method. Following optimisation to the TAC of each target renogram, the afferent flow rate parameters were calculated.
Following optimisation of models, afferent flow rate parameters, expressed as arbitrary units, (mean 0.15, SD 0.06) in acutely obstructed kidneys, were typically reduced in comparison with those of normal kidneys (mean 0.44, SD 0.04). (Paired t test; P<0.005). By contrast, this reduction in afferent flow rate parameter was greater than the reduction in differential tracer uptake for the obstructed kidney (divided renal function of the obstructed group; mean 0.3, SD 0.14 compared with the control group; mean 0.45, SD 0.05 (P<0.05).
Optimised modelling of TACs of obstructed renograms is feasible and may provide a more sensitive index of parenchymal dysfunction in early obstruction than comparing divided renal tracer uptake.
在单侧急性肾梗阻中，注射示踪剂后计算的分肾功能摄取可能正常。通过摄取测量的分肾功能对梗阻侧肾血浆流量（RPF）的下降可能不敏感。本研究分析了优化的肾图时间活动曲线（TAC）模型的前向流率参数。前向流率参数对分肾功能摄取的 RPF 变化的敏感性可能不同，并且在肾梗阻时对皮质功能的变化可能更敏感。
研究了 24 例使用 99mTc 标记的巯基乙酰三甘氨酸（MAG3）的背景校正肾图 TAC，其中单侧梗阻模式 24 例，正常对照肾图 TAC 6 例。使用专门的软件（ModelMaker，Cherwell Scientific）和 Marquardt 最小二乘法对每个曲线的优化计算模型进行构建。对每个目标肾图的 TAC 进行优化后，计算前向流率参数。
对模型进行优化后，以任意单位表示的前向流率参数（均值 0.15，SD 0.06）在急性梗阻肾脏中通常低于正常肾脏（均值 0.44，SD 0.04）。（配对 t 检验；P<0.005）。相比之下，这种前向流率参数的减少大于梗阻侧的示踪剂摄取差异（梗阻组的分肾功能；均值 0.3，SD 0.14 与对照组；均值 0.45，SD 0.05（P<0.05）。
对梗阻肾图 TAC 的优化建模是可行的，并且与比较分肾功能摄取相比，可能提供早期梗阻时实质功能障碍的更敏感指标。
