@article{oai:repo.qst.go.jp:00045272,
 author = {Mishina, Masahiro and Ohyama, Masashi and Ishii, Kenji and Kitamura, Shin and Kimura, Yuichi and Oda, Keiichi and Kawamura, Kazunori and Sasaki, Touru and Kobayashi, Shirou and Katayama, Yasuo and Ishiwata, Kiichi and 石井 賢二 and 木村 裕一 and 織田 圭一 and 石渡 喜一},
 issue = {3},
 journal = {Annals of Nuclear Medicine},
 month = {May},
 note = {Objective:  The sigma1 receptor is considered to be involved in cognitive function. A postmortem study reported that the sigma1 receptors were reduced in the hippocampus in Alzheimer's disease (AD). However, in vivo imaging of sigma1 receptors in the brain of AD patients has not been reported. The aim of this study is to investigate the mapping of sigma1 receptors in AD using [11C]SA4503 positron emission tomography (PET). 
Methods:  We studied fi ve AD patients and seven elderly volunteers. A dynamic series of decay-corrected PET data acquisition was performed for 90 min starting at the time of the injection of 500 MBq of [11C]SA4503. A twotissue three-compartment model was used to estimate K1, k2, k3, k4, and the delay between metabolite-corrected plasma and tissue time activity using a Gauss-Newton algorithm. The ratio of k3 to k4 was computed as the binding potential (BP), which is linearly related to the density of sigma1 receptors. Unpaired t tests were used to compare K1 and BP in patients with AD and normal subjects.
Results:  As compared with normals, BP in the AD was signifi cantly lower in the frontal, temporal, and occipital lobe, cerebellum and thalamus, whereas K1 was signifi - cantly lower in the parietal lobe.
Conclusions:  [11C]SA4503 PET can demonstrate that the density of cerebral and cerebellar sigma1 receptors is reduced in early AD.},
 pages = {151--156},
 title = {Low density of sigma1 receptors in early Alzheimer's disease},
 volume = {22},
 year = {2008}
}