@misc{oai:repo.qst.go.jp:00063145,
 author = {Arakawa, Ryosuke and Ichimiya, Tetsuya and Ito, Hiroshi and Takano, Akihiro and Okumura, Masaki and Takahashi, Hidehiko and Takano, Harumasa and Yasuno, Fumihiko and Kato, Motoichiro and Okubo, Yoshiro and Suhara, Tetsuya and 荒川 亮介 and 一宮 哲哉 and 伊藤 浩 and 高野 晶寛 and 奥村 正紀 and 高橋 英彦 and 高野 晴成 and 安野 史彦 and 加藤 元一郎 and 大久保 善朗 and 須原 哲也},
 month = {Jul},
 note = {Objectives: Previous in vivo imaging studies using positron emission tomography (PET) or single photon emission computed tomography (SPECT) reported no difference in dopamine transporter (DAT) bindings between control subjects and patients with schizophrenia[1,2]. However, those studies evaluated DAT binding only in the striatum, as DAT density in extrastriatal regions is very low. The recent development of [11C]PE2I, which has high affinity and selectivity for DAT, allows the evaluation of extrastiatal DAT bindings[3]. 
\nMethods: Eight patients (6 men, 2 women; mean age 36.5 +- 9.5 yr, range 25-52 yr) diagnosed with schizophrenia participated in this study. Six of them were antipsychotic naïve and two had been antipsychotic free for at least six months before PET measurement. Psychopathological symptoms were assessed on the same day as the PET scans using the Positive and Negative Syndrome Scale (PANSS). Twelve normal control subjects (10 men, 2 women; mean age 33.2 +- 12.0 yr, range 23-56 yr) also participated. A dynamic PET scan was performed for 90 minutes after intravenous bolus injection of 214.7 +- 13.7 MBq of [11C]PE2I. The specific radioactivity of [11C]PE2I was 344.5 +- 355.3 MBq/nmol. All PET images were transformed into the standard brain size and shape using the statistical parametric mapping (SPM2) system. Regions of interest (ROIs) were drawn on all anatomically standardized PET images with reference to the T1-weighted MR images. ROIs were defined for the cerebellar cortex, caudate head, putamen, substantia nigra and thalamus. Binding potential (BPND) was calculated by the simplified reference tissue model method. The cerebellum was used as reference region because of its negligible density of DAT. After complete description of this study, written informed consent was obtained from all subjects. The study was approved by the Ethics and Radiation Safety Committee of the National Institute of Radiological Sciences, Chiba, Japan.
\nResults: The BPND value in the thalamus was significant higher in patients with schizophrenia (0.36 +- 0.07) than in controls (0.28 +- 0.08) (two-tailed t-test; d.f.=18, t=2.16, P=0.044). There were no significant differences in BPND between the two groups in the caudate, putamen or substantia nigra. In patients with schizophrenia, there were significant positive correlations between BPND in the thalamus and total PANSS score (Pearson's correlation coefficient; r=0.75, P=0.032), positive (r=0.78, P=0.023) and negative scores (r=0.82, P=0.014), but no correlation was observed with the general PANSS score. There was no significant correlation between BPND in other regions and any of PANSS scores. 
\nConclusions: Although the function of DAT in the thalamus has remained unclear, high DAT bindings may suggest a hyper-dopaminergic state of pre-synaptic dopamine function in patients with schizophrenia.
\nReferences: 
[1] Laakso A et al. Am J Psychiatry 2000; 157: 269-71.
[2] Schmitt GJ et al. Schizophr Res 2008; 101: 133-41. 
[3] Hirvonen J et al. J Cereb Blood Flow Metab 2008; 28: 1059-69., Brain '09 & Brain PET '09},
 title = {INCREASE IN THALAMIC BINDING OF [11C]PE2I IN PATIENTS WITH SCHIZOPHRENIA: A POSITRON EMISSION TOMOGRAPHY STUDY OF DOPAMINE TRANSPORTER},
 year = {2009}
}