Moonen M, Jacobsson L, Granerus G
Department of Clinical Physiology, Sahlgren's Hospital, University of Göteborg, Sweden.
Nucl Med Commun. 1994 Sep;15(9):673-9.
In an attempt to improve the reliability in estimating glomerular filtration rate (GFR) from gamma camera renography without blood sampling, we have investigated the impact of plasma input region of interest (ROI) size and location and the effect of the time delay between the circulation peak in the renal curves and in the plasma curve. An uptake index (UI) was calculated using plasma ROIs of five different sizes (8-56 cm2) and compared with measured 51Cr-EDTA clearance. The spread of the estimated GFR was not affected by the variations in plasma ROI size but different relations were obtained between UI and GFR. The plasma ROI markedly affected the estimated GFR (a deviation of 3.5 cm from the maximal region led to an overestimation of the GFR of 36%). Furthermore, the most reliable GFR estimate (S.D. 10.5 ml min-1) was achieved by including the whole circulation peak in the calculation time interval of the time delay-adjusted renogram, except the first frame. The time delay adjustment also enabled the calculation of a factor alpha, which represents the ratio between the blood volume within the renal ROI and that within the plasma input ROI. An abnormal alpha/UI ratio would suggest an unreliable GFR estimation.
为了在不进行采血的情况下，提高通过γ相机肾图估计肾小球滤过率（GFR）的可靠性，我们研究了血浆输入感兴趣区（ROI）的大小和位置的影响，以及肾曲线和血浆曲线中循环峰值之间的时间延迟的影响。使用五种不同大小（8 - 56平方厘米）的血浆ROI计算摄取指数（UI），并与测量的51Cr - EDTA清除率进行比较。估计的GFR的离散度不受血浆ROI大小变化的影响，但UI与GFR之间获得了不同的关系。血浆ROI显著影响估计的GFR（从最大区域偏离3.5厘米导致GFR高估36%）。此外，通过在时间延迟调整后的肾图的计算时间间隔内纳入整个循环峰值（除第一帧外），可实现最可靠的GFR估计（标准差为10.5毫升/分钟）。时间延迟调整还能够计算一个α因子，该因子代表肾ROI内的血容量与血浆输入ROI内的血容量之比。异常的α/UI比值表明GFR估计不可靠。
