The objective of this study was to demonstrate 1H MR spectroscopy (MRS) changes in cerebral metabolites after acute head trauma. Twenty-five patients (12 children, 13 adults) were examined with quantitative 1H MRS after closed head injury. Clinical grade (Glasgow Coma Scale [GCS]) and outcome (Rancho Los Amigos Medical Center Outcome Score [ROS]) were correlated with quantitative neurochemical findings. N-acetylaspartate (NAA), a neuronal and axonal marker, was reduced (P < .03-.001). In children, a reduced NAA/creatine plus phosphocreatine (Cr) level and the presence of detectable lipid/lactate predicted bad outcome (sensitivity, 89%; specificity, 89%). The first MRS examination of all patients correlated with ROS versus NAA (r = .65, P < .0001). Although most patients showed MRS abnormalities, striking heterogeneity of 1H MRS characterized the individual patients. 1H MRS identifies multiple patterns of diffuse brain injury after blunt head trauma. There was a strong correlation between MRS and outcome. Future prospective studies will be needed to determine the clinical usefulness of MRS in predicting outcome from closed head injury.

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Positron emission tomography (PET) studies with radiolabeled dopamine D2-like receptor ligands reveal d-amphetamine-evoked increases in the competition from endogenous dopamine. However, the corresponding effects of methylenedioxymethamphetamine (MDMA, "Ecstasy"), which releases catecholamines and also serotonin, are unknown. Using PET, we measured the binding potentials (pBs) of the benzamide [11C]raclopride and the butyrophenone N-[11C]methylspiperone ([11C]NMSP) in brain of living pigs first in a baseline condition and at 45 and 165 min after infusion of (+/-)-MDMA-HCl (1 mg/kg, i.v.). Concomitant studies of cerebral blood flow did not reveal significant perfusion changes in the cerebellum reference region or in striatum, supporting the present use of reference tissue methods for the mapping of MDMA-evoked pB changes. Relative to the baseline pB of [11C]raclopride for dopamine D(2/3) receptors in striatum (pB = 1.5-2.2), MDMA-treatment reduced pB by 35% in the first posttreatment scan and by 22% in the second posttreatment scan, comparable to changes typically evoked by d-amphetamine at a similar dose. In most previous studies, the in vivo binding of butyrophenones has been nearly insensitive to d-amphetamine-evoked dopamine release. However, we found the baseline pB of [11C]NMSP for dopamine D2-like receptors in striatum (pB = 4-5) was decreased by 30% in the first post-MDMA scan and by 50% in the second post-MDMA scan, irrespective of assumptions about the extent of equilibrium binding attained during the 90-min-long PET recordings. Distinct properties of MDMA such as simultaneous release of dopamine and serotonin in brain may account for the present finding of progressive decline in the availability of [11C]NMSP binding sites in striatum.

The activity of both isozymes of monoamine oxidase (MAO) is reduced by 50% in the brain of human smokers. We hypothesized that this is not an epiphenomenon, but should bring about potentiation of the action of psychostimulant drugs. To test this hypothesis, we carried out serial positron emission tomography (PET) studies in Göttingen miniature pigs to measure the binding of the MAO-A ligand [11C]harmine and to measure the changes in [11C]raclopride binding evoked by a low dose of amphetamine (0.7 mg/kg as free base, i.v.), first in a baseline condition, and, one month later, after acute treatment with pargyline (2 x 3 mg/kg as free base, i.m.). In the baseline, the distribution volume of [11C]harmine relative to the arterial input (V(d), ml g(-1)) ranged from 74 ml g(-1) in cerebellum to 139 ml g(-1) in the medial hypothalamus. Pargyline treatment reduced the magnitude of V(d) globally to 34-54 ml g(-1). Nearly complete displacement of [11C]harmine binding was detected in neocortex and striatum, but there was evidence for pargyline-resistant binding in the pituitary gland and diencephalon. In the baseline condition, the low dose of amphetamine evoked a 14% decline in the binding potential (BP) (pB) of [11C]raclopride in striatum (P = 0.026). After pargyline treatment, the amphetamine effect was of similar magnitude (-11%), although not statistically significant (P = 0.054). However, the second amphetamine challenge evoked a 24% reduction in [11C]raclopride pB relative to the original baseline condition (P = 0.018). Present results do not strongly support our hypothesis that MAO inhibition should potentiate the amphetamine-evoked dopamine release as measured in the [11C]raclopride competition paradigm.

Background177Lu is used in peptide receptor radionuclide therapies for the treatment of neuroendocrine tumors. Based on the recent literature, SST2 antagonists are superior to agonists in tumor uptake. The compound OPS201 is the novel somatostatin antagonist showing the highest SST2 affinity. The aim of this study was to measure the in vivo biodistribution and dosimetry of 177Lu-OPS201 in five anesthetized Danish Landrace pigs as an appropriate substitute for humans to quantitatively assess the absorbed doses for future clinical applications.Results177Lu-OPS201 was obtained with a specific activity ranging from 10 to 17 MBq/μg. Prior to administration, the radiochemical purity was measured as s > 99.7 % in all cases. After injection, fast clearance of the compound from the blood stream was observed. Less than 5 % of the injected activity was presented in blood 10 min after injection. A series of SPECT/CT and whole-body scans conducted until 10 days after intravenous injection showed uptake mostly in the liver, spine, and kidneys. There was no visible uptake in the spleen. Blood samples were taken to determine the time-activity curve in the blood. Time-activity curves and time-integrated activity coefficients were calculated for the organs showing visible uptake. Based on these data, the absorbed organ dose coefficients for a 70-kg patient were calculated with OLINDA/EXM. For humans after an injection of 5 GBq 177Lu-OPS201, the highest predicted absorbed doses are obtained for the kidneys (13.7 Gy), the osteogenic cells (3.9 Gy), the urinary bladder wall (1.8 Gy), and the liver (1.0 Gy). No metabolites of 177Lu-OPS201 were found by radio HPLC analysis. None of the absorbed doses calculated will exceed organ toxicity levels.ConclusionsThe 177Lu-OPS201 was well tolerated and caused no abnormal physiological or behavioral signs. In vivo distributions and absorbed doses of pigs are comparable to those observed in other publications. According to the biodistribution data in pigs, presented in this work, the expected radiation exposure in humans will be within the acceptable range.Electronic supplementary materialThe online version of this article (doi:10.1186/s13550-016-0204-9) contains supplementary material, which is available to authorized users.