@article{oai:repo.qst.go.jp:00046544,
 author = {Kodaka, Fumitoshi and Ito, Hiroshi and Kimura, Yasuyuki and Fujie, Saori and Takano, Harumasa and Fujiwara, Hironobu and Sasaki, Takeshi and Nakayama, Kazuhiko and Halldin, Christer and Farde, Lars and Suhara, Tetsuya and 小高 文聰 and 伊藤 浩 and 木村 泰之 and 藤江 沙織 and 高野 晴成 and 藤原 広臨 and 佐々木 健至 and ハルディン クリスタ and 須原 哲也},
 issue = {4},
 journal = {European Journal of Nuclear Medicine and Molecular Imaging},
 month = {Apr},
 note = {Purpose: Dopamine D2/3 receptors (D2/3Rs) have two affinity states for endogenous dopamine, referred to as high-affinity state (D2/3HIGH), which has a high affinity for endogenous dopamine, and low-affinity state (D2/3LOW). The density of D2/3HIGH can be measured with (R)-2-11CH3O-N-n-propylnorapomorphine ([11C]MNPA), while total density of D2/3HIGH and D2/3LOW (D2/3Rs) can be measured with [11C]raclopride using positron emission tomography (PET). Thus, the ratio of the binding potential (BP) of [11C]MNPA to that of [11C]raclopride ([11C]MNPA/[11C]raclopride) may reflect the proportion of the density of D2/3HIGH to that of D2/3Rs. In the caudate and putamen, [11C]MNPA/[11C]raclopride reflects the proportion of the density of D2HIGH to that of D2Rs. To evaluate the reliability of the PET paradigm with [11C]MNPA and [11C]raclopride, we investigated the test-retest reproducibility of non-displaceable BP (BPND) measured with [11C]MNPA, and of [11C]MNPA/[11C]raclopride in healthy humans.
Methods: Eleven healthy male volunteers underwent two sets of PET studies on separate days that each included [11C]MNPA and [11C]raclopride scans. BPND values in the caudate and putamen were calculated. Test-retest reproducibility of BPND of [11C]MNPA, and  [11C]MNPA/[11C]raclopride, was assessed by intra-subject variability (absolute variability) and test-retest reliability (intra-class correlation coefficient: ICC). 
Results: The absolute variability of [11C]MNPA BPND was 5.30 +- 3.96% and 12.3 +- 7.95% and the ICC values of [11C]MNPA BPND were 0.72 and 0.82 in the caudate and putamen, respectively. The absolute variability of [11C]MNPA/[11C]raclopride was 6.11 +- 3.68% and 11.60 +- 5.70% and the ICC values of [11C]MNPA/[11C]raclopride were 0.79 and 0.80 in the caudate and putamen, respectively.
Conclusion: In the present preliminary study, the test-retest reproducibility of BPND of [11C]MNPA and of [11C]MNPA/[11C]raclopride was reliable in the caudate and putamen.},
 pages = {574--579},
 title = {Test-retest reproducibility of dopamine D2/3 receptor binding in human brain measured by PET with [11C]MNPA and [11C]raclopride},
 volume = {40},
 year = {2013}
}