Kanai Yasukazu, Hasegawa Shinji, Kimura Yasuyuki, Oku Naohiko, Ito Hiroshi, Fukuda Hiroshi, Hatazawa Jun
Department of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Ann Nucl Med. 2007 Sep;21(7):387-91. doi: 10.1007/s12149-007-0038-7. Epub 2007 Sep 25.
N-isopropyl-4-[123I]iodoamphetamine (123I-IMP) is a lipophilic compound utilized for cerebral blood flow (CBF) measurement with single photon emission computed tomography (SPECT). Two different 123I-IMP products (IMP(A) and IMP(B)) are commercially available. We examined the radiochemical purity, unmetabolized fraction, and octanol extraction fraction in arterial blood, and the regional brain uptake of IMP(A) and IMP(B) in a rat model. IMP(B) (96.4% +/- 0.08%, P < 0.05) showed significantly higher radiochemical purity than IMP(A) (95.5% +/- 0.20%). The mean unmetabolized fraction in arterial blood taken at 10 min after intravenous administration of IMP(B) (69.5% +/- 4.4%, P < 0.01) was significantly higher than that of IMP(A) (59.6% +/- 2.6%). The mean octanol extraction fraction of IMP(B) (75.0% +/- 1.3%, P < 0.01) was also significantly higher than that of IMP(A) (67.2% +/- 0.8%). The mean levels of radioactivity in arterial blood sampled at 10 min after injection and mean regional brain radioactivity (cerebral cortices, basal ganglia, brain stem, and cerebellum) at 10-12 min after injection were not significantly different between IMP(A) and IMP(B). The present study indicates differences in the radiochemical purity and the unmetabolized and octanol extraction fraction in arterial blood between the two commercially available 123I-IMP products. The appropriate octanol extraction fractions for IMP(A) and IMP(B) should be determined in humans and employed for quantitative CBF measurement in clinical SPECT.
N-异丙基-4-[123I]碘安非他明（123I-IMP）是一种亲脂性化合物，用于通过单光子发射计算机断层扫描（SPECT）测量脑血流量（CBF）。有两种不同的123I-IMP产品（IMP(A)和IMP(B)）可供商业使用。我们在大鼠模型中检测了动脉血中的放射化学纯度、未代谢部分和辛醇萃取率，以及IMP(A)和IMP(B)在脑内的区域摄取情况。IMP(B)（96.4%±0.08%，P<0.05）的放射化学纯度显著高于IMP(A)（95.5%±0.20%）。静脉注射IMP(B)后10分钟采集的动脉血中，平均未代谢部分（69.5%±4.4%，P<0.01）显著高于IMP(A)（59.6%±2.6%）。IMP(B)的平均辛醇萃取率（75.0%±1.3%，P<0.01）也显著高于IMP(A)（67.2%±0.8%）。注射后10分钟采集的动脉血放射性平均水平以及注射后10-12分钟脑内区域放射性平均水平（大脑皮层、基底神经节、脑干和小脑）在IMP(A)和IMP(B)之间无显著差异。本研究表明，两种市售123I-IMP产品在放射化学纯度以及动脉血中的未代谢和辛醇萃取率方面存在差异。应在人体中确定IMP(A)和IMP(B)合适的辛醇萃取率，并将其用于临床SPECT的定量CBF测量。
