Purpose: Although two norepinephrine transporter (NET) radioligands, (S,S)-[(18)F]FMeNER-D(2) and (S,S)-[(11)C]MeNER, have been reported to have different characteristics, there has not been a direct comparative study in vivo.
Methods: In this preliminary study, two rhesus monkeys underwent three PET measurements each, one with (S,S)-[(18)F]FMeNER-D(2) and two with different radioactivity of (S,S)-[(11)C]MeNER (360 and 175 MBq). The regional brain uptakes and BP(ND) values from reference tissue models with different time lengths were compared.
Results: The regional uptakes in the thalamus and the brainstem with (S,S)-[(11)C]MeNER did not always reach the peak during 123-min measurements while those with (S,S)-[(18)F]FMeNER-D(2) reached the peak before 30 min. The regional BP(ND) values of (S,S)-[(18)F]FMeNER-D(2) were stable after 150-min measurement lengths while those of (S,S)-[(11)C]MeNER were not stable during 123-min measurements.
Conclusion: (S,S)-[(18)F]FMeNER-D(2) appears to be superior for the quantitative analysis with reference tissue models in the rhesus monkey.