Ichihara T, Maeda H, Yamakado K, Motomura N, Matsumura K, Takeda K, Nakagawa T
Toshiba Medical Engineering Laboratory, Tochigi-ken, Japan.
Eur J Nucl Med. 1997 Jan;24(1):59-67. doi: 10.1007/BF01728310.
A new method for quantitative liver study was developed using the tracer technetium-99m diethylene triamine penta-acetic acid-galactosyl human serum albumin (99mTc-GSA), an analog ligand of the asialoglycoprotein receptor, which is a hepatocyte surface receptor specific for galactose-terminated glycoproteins. For quantitative dynamic single-photon emission tomographic (SPET) studies, attenuation compensation using transmission computed tomography (TCT) and the triple energy window (TEW) scatter compensation method were evaluated. As the TCT source, we used an uncollimated multi-tube source with the TEW scatter compensation method. To verify the accuracy of cross-calibrated SPET values as compared with measured radioactivities, we performed SPET of a cylindrical water pool phantom which contains seven hot rods filled with different concentrations of 99mTc activities, simulating the scan conditions in human studies. The results of the phantom studies showed good linearity and accuracy of the SPET values, with R2=0.993 and a regression line of y=0.941x+5.48. From the analysis of a kinetic model based on a one-compartment model, focussing on the initial stage of several minutes after 99mTc-GSA injection and taking the physiological expression presented in a three-compartment analysis into account, we introduced the Rutland equation (Patlak plot) in the 99mTc-GSA study by which the overall and regional effective hepatic blood flow (EHBF) and hepatic blood pool volume were determined. Preliminary clinical evaluations were performed for four normal male subjects (23-35 years of age) and one patient. Forty sequential 30-s dynamic SPET acquisitions were obtained for a period of 20 min following the intravenous injection of 99mTc-GSA with venous blood sampling at 10 min. After scatter compensation, the SPET images were reconstructed with attenuation compensation using an attenuation map obtained from TCT. The average normal value for the total EHBF was 468+/-83 ml/min and that for the hepatic blood pool volume, 777+/-123 ml. Functional images of the distribution of regional values of EHBF (ml/min/voxel) and hepatic blood pool volume (ml/voxel) were also generated corresponding to the original SPET images. The EHBF images showed regional liver function, higher in the right lobe than the left lobe in the normal cases, and the heptic blood pool volume images showed the distribution of intensified high values along major vascular structures. Receptor imaging with 99mTc-GSA using the Rutland method and dynamic SPET with scatter and attenuation compensation is an effective technique that allows the evaluation of total and regional hepatic functional parameters (EHBF, hepatic blood pool) in vivo.
一种用于肝脏定量研究的新方法被开发出来，该方法使用示踪剂锝-99m二乙烯三胺五乙酸-半乳糖基人血清白蛋白（99mTc-GSA），它是去唾液酸糖蛋白受体的类似配体，而去唾液酸糖蛋白受体是肝细胞表面针对半乳糖末端糖蛋白的特异性受体。对于定量动态单光子发射断层扫描（SPET）研究，评估了使用传输计算机断层扫描（TCT）的衰减补偿和三能量窗（TEW）散射补偿方法。作为TCT源，我们使用了采用TEW散射补偿方法的非准直多管源。为了验证交叉校准的SPET值与测量放射性相比的准确性，我们对一个圆柱形水池模型进行了SPET，该模型包含七个装有不同浓度99mTc活性的热棒，模拟人体研究中的扫描条件。模型研究结果显示SPET值具有良好的线性和准确性，R2 = 0.993，回归线为y = 0.941x + 5.48。基于单室模型的动力学模型分析，聚焦于99mTc-GSA注射后几分钟的初始阶段，并考虑三室分析中呈现的生理表达，我们在99mTc-GSA研究中引入了拉特兰方程（帕塔克图），通过该方程确定了整体和区域有效肝血流量（EHBF）以及肝血池容积。对四名正常男性受试者（23 - 35岁）和一名患者进行了初步临床评估。在静脉注射99mTc-GSA后20分钟内，每隔30秒进行40次动态SPET采集，并在10分钟时采集静脉血样。经过散射补偿后，使用从TCT获得的衰减图进行衰减补偿重建SPET图像。总EHBF的平均正常值为468±83 ml/min，肝血池容积的平均正常值为777±123 ml。还生成了与原始SPET图像相对应的EHBF（ml/min/体素）和肝血池容积（ml/体素）区域值分布的功能图像。EHBF图像显示了区域肝功能，在正常情况下右叶高于左叶，肝血池容积图像显示了沿主要血管结构强化高值的分布。使用拉特兰方法的99mTc-GSA受体成像以及具有散射和衰减补偿的动态SPET是一种有效的技术，可在体内评估整体和区域肝功能参数（EHBF、肝血池）。
