Ito Hiroshi, Sato Tachio, Odagiri Hayato, Inoue Kentaro, Shidahara Miho, Suhara Tetsuya, Hatazawa Jun, Fukuda Hiroshi
Department of Nuclear Medicine and Radiology, Division of Brain Sciences, Institute of Development, Aging and Cancer, Tohoku University.
Ann Nucl Med. 2006 Aug;20(7):493-8. doi: 10.1007/BF02987259.
Iodine-123 (123I)-labeled N-isopropyl-4-iodoamphetamine (IMP) has been used as a cerebral blood flow (CBF) tracer for single-photon emission computed tomography (SPECT). An autoradiographic (ARG) method has been developed for the quantitation of CBF by IMP and SPECT. Two IMPs (IMPA and IMPB) produced by different radiopharmaceutical companies are marketed in Japan. In the present study, whole-body distributions including brain and blood of the two IMPs were compared in the same human subjects.
Two brain SPECT studies using IMPA or IMPB were performed on separate days in six young healthy men. Whole-body scans were also obtained with a large field-of-view single-head gamma camera. One-point arterial blood sampling was performed at 10 min after injection of IMP to measure both the radioactivity concentrations of whole blood and of octanol-extracted components.
No significant differences between the two tracers were observed in body distribution, tracer kinetics in brain, or regional distribution in brain. However, the octanol extraction fraction in blood was significantly different between the two tracers. Radiochemical purity was slightly but significantly different between the tracers.
In the ARG method, arterial input function is determined by calibration of a standard input function with the radioactivity concentration of arterial whole blood. Because the standard input function in the ARG method was obtained using IMPA, the standard input function obtained for IMPB should be used when CBF is calculated by the ARG method with IMPB.
碘-123（123I）标记的N-异丙基-4-碘安非他明（IMP）已被用作单光子发射计算机断层扫描（SPECT）的脑血流（CBF）示踪剂。已开发出一种放射自显影（ARG）方法，用于通过IMP和SPECT定量CBF。由不同放射性药物公司生产的两种IMP（IMPA和IMPB）在日本上市。在本研究中，对同一人类受试者中两种IMP的包括脑和血液在内的全身分布进行了比较。
在六名年轻健康男性中，在不同日期分别使用IMPA或IMPB进行了两项脑SPECT研究。还使用大视野单头伽马相机进行了全身扫描。在注射IMP后10分钟进行单点动脉血采样，以测量全血和辛醇萃取成分的放射性浓度。
在身体分布、脑中示踪剂动力学或脑内区域分布方面，未观察到两种示踪剂之间存在显著差异。然而，两种示踪剂之间血液中的辛醇萃取分数存在显著差异。示踪剂之间的放射化学纯度略有但显著不同。
在ARG方法中，动脉输入函数通过用动脉全血的放射性浓度校准标准输入函数来确定。由于ARG方法中的标准输入函数是使用IMPA获得的，因此当使用IMPB通过ARG方法计算CBF时，应使用为IMPB获得的标准输入函数。
