Methamphetamine dependence can lead to psychotic symptoms which may be mediated by frontal, striatal, limbic, and thalamic regions. There are few neuroimaging data that allow comparison of individuals with methamphetamine dependence who do, and do not, have psychosis. Two complementary imaging techniques were employed to investigate neurocircuitry associated with methamphetamine dependence with and without psychotic symptoms. Three groups of participants were recruited: methamphetamine dependent (MAA) (N = 11), methamphetamine dependent with psychotic symptoms (MAP) (N = 14), and controls (N = 14). Resting brain glucose metabolism was measured using [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) and cerebral perfusion was assessed using arterial spin labelling (ASL) magnetic resonance imaging. Methamphetamine abusers (MAA and MAP groups) had decreased glucose metabolism compared to healthy controls in the left insula, left precentral gyrus, and the anterior cingulate cortex. Compared to MAA participants, MAP participants had 1) decreased glucose metabolism in the left precentral gyrus and the left inferior frontal gyrus and 2) increased glucose metabolism in the putamen and pallidum. MAP participants also had increased cerebral perfusion in the right putamen and right pallidum compared to MAA. Findings support the involvement of frontal, striatal, and limbic regions in methamphetamine dependence. Furthermore, they indicate that glucose metabolism and cerebral perfusion in these regions are disrupted in methamphetamine dependent individuals with psychotic symptoms.

The use of radionuclides as potential therapeutic radiopharmaceuticals is increasingly investigated. An important aspect is the delivery of the radionuclide to the target, i.e. the radionuclide is not lost from the chelating agent. For in vivo generators, it is not only the log K of complexation between the metal ion and the chelator that is important, but also whether the daughter radionuclide stays inside the chelator after decay of the parent radionuclide. In our previous work, we showed that the classical recoil effect is only applicable for decays with a Q value higher than 0.6 MeV (in the atomic mass range around 100). However, Zhernosekov et al. [1] published a result for¹⁴⁰Nd/¹⁴⁰Pr (Q = 0.222 MeV) which indicated that >95% of the daughter (¹⁴⁰Pr) was lost by a DOTA chelator upon decay of¹⁴⁰Nd. The authors ascribed this to the & ldquo;post-effect”. Their experiment was repeated with the¹⁶⁶Dy/¹⁶⁶Ho generator to ascertain whether our calculations were correct. It was found that 72% of the daughter (¹⁶⁶Ho) was liberated from the DOTA chelator, indicating that the “post effect” does exist in contrast to our recoil calculations. Upon further investigation, we determined that one should not only consider recoil energy levels but also the mode of decay which was able to explain the partial recoil found for¹⁶⁶Dy/¹⁶⁶Ho. It is concluded for the¹⁶⁶Dy/¹⁶⁶Ho system that the low recoil energy of the daughter nucleus¹⁶⁶Ho is not a sufficient reason to rule out release of the nuclide from chelators. On the other hand, we found that the ratio of the¹⁶⁶Ho that gets released corresponds to the ratio of relaxation of Ho atoms via the Auger process.