Ito H, Kawashima R, Koyama M, Goto R, Sato K, Ono S, Fukuda H
Department of Nuclear Medicine and Radiology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
Ann Nucl Med. 1997 May;11(2):101-8. doi: 10.1007/BF03164817.
Iodine-123-iomazenil (Iomazenil) is a ligand of central type benzodiazepine receptors for single photon emission computed tomography (SPECT). Previously we reported a simple, table look-up method for quantification of its binding potential (BP) by using two SPECT scans and calibrated standard input function with one blood sampling. This method is based on a two-compartment model (K1: influx rate constant; k2: efflux rate constant; Vd (= K1/k2): the total distribution volume corresponding BP), and requires two SPECT scans for calculating both K1 and Vd values. If the K1 value in the two-compartment model can be assumed to be constant, the radioactivity of one SPECT scan at 180 min after injection can be considered to tabulate as a function of Vd for a given K1 value and a given input function, and a table look-up procedure provides the corresponding Vd value. The purpose of this study was to develop a simple, autoradiographic method for quantification of BP by using one SPECT scan and calibrated standard input function with one blood sampling. SPECT studies were performed on 14 patients. A dynamic SPECT scan was initiated following an intravenous bolus injection of Iomazenil. A static SPECT scan was performed at 180 min after the injection. Frequent blood sampling from the brachial artery was performed on all subjects to determine the arterial input function. Simulation studies revealed that errors in calculated Vd values were around +/-10-15% for varied K1 values. A good correlation was observed between total distribution volume values calculated by three-compartment model analysis and those calculated by the present method (r = 0.90), supporting the validity of this method. The present method is simple and applicable for clinical use, and will be able to provide images of BP.
碘-123-碘美西尼（碘美西尼）是一种用于单光子发射计算机断层扫描（SPECT）的中枢型苯二氮䓬受体配体。此前我们报道了一种简单的查表法，通过两次SPECT扫描和一次血样采集的校准标准输入函数来定量其结合潜能（BP）。该方法基于双室模型（K1：流入速率常数；k2：流出速率常数；Vd（=K1/k2）：与BP对应的总分布容积），需要两次SPECT扫描来计算K1和Vd值。如果双室模型中的K1值可以假定为常数，那么注射后180分钟时一次SPECT扫描的放射性可被视为针对给定的K1值和给定的输入函数作为Vd的函数制成表格，通过查表程序可得到相应的Vd值。本研究的目的是开发一种简单的放射自显影方法，通过一次SPECT扫描和一次血样采集的校准标准输入函数来定量BP。对14名患者进行了SPECT研究。静脉推注碘美西尼后开始动态SPECT扫描。注射后180分钟进行静态SPECT扫描。对所有受试者从肱动脉频繁采血以确定动脉输入函数。模拟研究表明，对于不同的K1值，计算得到的Vd值误差约为±10 - 15%。三室模型分析计算得到的总分布容积值与本方法计算得到的总分布容积值之间观察到良好的相关性（r = 0.90），支持了该方法的有效性。本方法简单且适用于临床应用，并且能够提供BP图像。
