Test-retest reproducibility of dopamine D2/3 receptor binding in human brain measured by PET with [11C]MNPA and [11C]raclopride.

Fumitoshi Kodaka, Hiroshi Ito, Yasuyuki Kimura, Saori Fujie, Harumasa Takano, Hironobu Fujiwara, Takeshi Sasaki, Kazuhiko Nakayama, Christer Halldin, Lars Farde, Tetsuya Suhara

European journal of nuclear medicine and molecular imaging 2013 Apr

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Dopamine D receptors (DRs) have two affinity states for endogenous dopamine, referred to as high-affinity state (D ), which has a high affinity for endogenous dopamine, and low-affinity state (D ). The density of D can be measured with (R)-2-CHO-N-n-propylnorapomorphine ([C]MNPA), while total density of D and D (DRs) can be measured with [C]raclopride using positron emission tomography (PET). Thus, the ratio of the binding potential (BP) of [C]MNPA to that of [C]raclopride ([C]MNPA/[C]raclopride) may reflect the proportion of the density of D to that of DRs. In the caudate and putamen, [C]MNPA/[C]raclopride reflects the proportion of the density of D to that of DRs. To evaluate the reliability of the PET paradigm with [C]MNPA and [C]raclopride, we investigated the test-retest reproducibility of non-displaceable BP (BP ) measured with [C]MNPA and of [C]MNPA/[C]raclopride in healthy humans. Eleven healthy male volunteers underwent two sets of PET studies on separate days that each included [C]MNPA and [C]raclopride scans. BP values in the caudate and putamen were calculated. Test-retest reproducibility of BP of [C]MNPA and [C]MNPA/[C]raclopride was assessed by intra-subject variability (absolute variability) and test-retest reliability (intraclass correlation coefficient: ICC). The absolute variability of [C]MNPA BP was 5.30 ± 3.96 % and 12.3 ± 7.95 % and the ICC values of [C]MNPA BP were 0.72 and 0.82 in the caudate and putamen, respectively. The absolute variability of [C]MNPA/[C]raclopride was 6.11 ± 3.68 % and 11.60 ± 5.70 % and the ICC values of [C]MNPA/[C]raclopride were 0.79 and 0.80 in the caudate and putamen, respectively. In the present preliminary study, the test-retest reproducibility of BP of [C]MNPA and of [C]MNPA/[C]raclopride was reliable in the caudate and putamen.

Citation

Fumitoshi Kodaka, Hiroshi Ito, Yasuyuki Kimura, Saori Fujie, Harumasa Takano, Hironobu Fujiwara, Takeshi Sasaki, Kazuhiko Nakayama, Christer Halldin, Lars Farde, Tetsuya Suhara. Test-retest reproducibility of dopamine D2/3 receptor binding in human brain measured by PET with [11C]MNPA and [11C]raclopride. European journal of nuclear medicine and molecular imaging. 2013 Apr;40(4):574-9