Inoue Y, Ohtake T, Yokoyama I, Yoshikawa K, Asai S, Ohtomo K
Department of Radiology, Institute of Medical Science, University of Tokyo, Japan.
J Nucl Med. 1999 May;40(5):793-8.
To develop a camera-based method for evaluating renal function with 99mTc-mercaptoacetyltriglycine (MAG3), we examined the relationship between various renogram parameters and 99mTc-MAG3 clearance.
Twenty-one patients underwent renal scintigraphy with 99mTc-MAG3. Eighty 3-s frames were obtained after the bolus injection of 250 MBq tracer, followed by the collection of 52 30-s frames. Regions of interest were drawn for the kidneys, perirenal background areas and subrenal background areas, and background-subtracted renograms were generated. Renal accumulation at 0.5-1.5, 0.5-2, 1-2, 1-2.5 and 1.5-2.5 min after tracer arrival in the kidney was calculated as area under the background-subtracted renogram, and percent renal uptake was obtained after correction for soft-tissue attenuation and injected dose. The slope of the renogram was determined for the same segments used in calculating area under the renogram, and slope index was computed as slope corrected for attenuation and injected dose. Percent renal uptakes and slope indices were correlated by linear regression analysis with 99mTc-MAG3 clearance measured using a single blood sampling method.
Among the values of percent renal uptake, the value obtained at 1.5-2.5 min using the perirenal background correlated best with 99mTc-MAG3 clearance. The slope index at 0.5-1.5 or 0.5-2 min using the subrenal background provided better accuracy than percent renal uptake for predicting clearance. There were no substantial differences in the relative function of the right kidney between the methods using percent renal uptake and slope index.
99mTc-MAG3 clearance can be assessed with acceptable accuracy by a camera-based method. The method based on the slope of the renogram may replace the one based on the area under the renogram in evaluating renal function from 99mTc-MAG3 renograms.
为开发一种基于相机的用99m锝-巯基乙酰三甘氨酸（MAG3）评估肾功能的方法，我们研究了各种肾图参数与99mTc-MAG3清除率之间的关系。
21例患者接受了99mTc-MAG3肾闪烁显像。静脉推注250MBq示踪剂后获取80个3秒的图像帧，随后收集52个30秒的图像帧。绘制肾脏、肾周背景区域和肾下背景区域的感兴趣区，并生成扣除背景后的肾图。示踪剂到达肾脏后0.5 - 1.5、0.5 - 2、1 - 2、1 - 2.5和1.5 - 2.5分钟时的肾脏摄取量计算为扣除背景后的肾图曲线下面积，并在校正软组织衰减和注射剂量后获得肾脏摄取百分比。在用于计算肾图曲线下面积的相同时间段内确定肾图斜率，并将斜率指数计算为校正衰减和注射剂量后的斜率。通过线性回归分析将肾脏摄取百分比和斜率指数与使用单次血样采集法测量的99mTc-MAG3清除率进行相关性分析。
在肾脏摄取百分比的值中，使用肾周背景在1.5 - 2.5分钟时获得的值与99mTc-MAG3清除率的相关性最佳。使用肾下背景在0.5 - 1.5或0.5 - 2分钟时的斜率指数在预测清除率方面比肾脏摄取百分比具有更高的准确性。在使用肾脏摄取百分比和斜率指数的方法之间，右肾的相对功能没有实质性差异。
基于相机的方法可以以可接受的准确性评估99mTc-MAG3清除率。在从99mTc-MAG3肾图评估肾功能时，基于肾图斜率的方法可能会取代基于肾图曲线下面积的方法。
