Ito Hiroshi, Inoue Kentaro, Goto Ryoi, Kinomura Shigeo, Taki Yasuyuki, Okada Ken, Sato Kazunori, Sato Tachio, Kanno Iwao, Fukuda Hiroshi
Department of Nuclear Medicine and Radiology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
Ann Nucl Med. 2006 Feb;20(2):131-8. doi: 10.1007/BF02985625.
Three accumulative tracers, iodine-123-labeled N-isopropyl-p-iodoamphetamine (I-123-IMP), technetium-99m-labeled hexamethylpropyleneamineoxime (Tc-99m-HMPAO), and technetium-99m-labeled ethyl cysteinate dimer (Tc-99m-ECD) are widely used to measure cerebral blood flow (CBF) in single-photon emission computed tomography (SPECT). In the present study, normal regional distribution of CBF measured with three different SPECT tracers was entered into a database and compared with regional distribution of CBF measured by positron emission tomography (PET) with H2(15)O. The regional distribution of tissue fractions of gray matter determined by voxel-based morphometry was also compared with SPECT and PET CBF distributions.
SPECT studies with I-123-IMP, Tc-99m-HMPAO, and Tc-99m-ECD were performed on 11, 20, and 17 healthy subjects, respectively. PET studies were performed on 11 healthy subjects. Magnetic resonance (MR) imaging studies for voxel-based morphometry were performed on 43 of the 48 subjects who underwent SPECT study. All SPECT, PET, and MR images were transformed into the standard brain format with the SPM2 system. The voxel values of each SPECT and PET image were globally normalized to 50 ml/100 ml/min. Gray matter, white matter, and cerebrospinal fluid images were segmented and extracted from all transformed MR images by applying voxel-based morphometry methods with the SPM2 system.
Regional distribution of all three SPECT tracers differed from that of H2150 in the pons, midbrain, thalamus, putamen, parahippocampal gyrus, posterior cingulate gyrus, temporal cortex, and occipital cortex. No significant correlations were observed between the tissue fraction of gray matter and CBF with any tracer.
Differences in regional distribution of SPECT tracers were considered to be caused mainly by differences in the mechanism of retention of tracers in the brain. Regional distribution of CBF was independent of regional distribution of gray matter fractions, and consequently the blood flow per gray matter volume differed for each brain region.
三种累积示踪剂，即碘-123标记的N-异丙基-p-碘安非他明（I-123-IMP）、锝-99m标记的六甲基丙烯胺肟（Tc-99m-HMPAO）和锝-99m标记的半胱氨酸乙酯二聚体（Tc-99m-ECD），被广泛用于单光子发射计算机断层扫描（SPECT）中测量脑血流量（CBF）。在本研究中，将用三种不同SPECT示踪剂测量的CBF正常区域分布输入数据库，并与用H2(15)O正电子发射断层扫描（PET）测量的CBF区域分布进行比较。还将基于体素形态学测定的灰质组织分数区域分布与SPECT和PET的CBF分布进行比较。
分别对11名、20名和17名健康受试者进行了I-123-IMP、Tc-99m-HMPAO和Tc-99m-ECD的SPECT研究。对11名健康受试者进行了PET研究。对48名接受SPECT研究的受试者中的43名进行了基于体素形态学的磁共振（MR）成像研究。所有SPECT、PET和MR图像均使用SPM2系统转换为标准脑格式。将每个SPECT和PET图像的体素值全局归一化为50 ml/100 ml/min。通过使用SPM2系统应用基于体素形态学方法，从所有转换后的MR图像中分割并提取灰质、白质和脑脊液图像。
在脑桥、中脑、丘脑、壳核、海马旁回、后扣带回、颞叶皮质和枕叶皮质中所有三种SPECT示踪剂的区域分布均与H2150的不同。在灰质组织分数与任何示踪剂的CBF之间未观察到显著相关性。
SPECT示踪剂区域分布的差异被认为主要是由示踪剂在脑中保留机制的差异引起的。CBF的区域分布与灰质分数的区域分布无关，因此每个脑区每单位灰质体积的血流量不同。
