![]() For instance, the glutamate hypothesis arose initially from observations that administration of ketamine and other non-competitive antagonists at the glutamatergic NMDA receptor (NMDAR) leads to psychological effects, which closely resemble symptoms that occur in schizophrenia. The advent of PET systems having a resolution of about 1 mm will thus provide a significant improvement for such examinations.īeyond dopamine, present evidence suggests alterations in other major neurotransmission systems in neuropsychiatric disorders including schizophrenia. Considering the hierarchical organization of the brain it cannot be excluded that some of these structures may have a key role in the pathophysiology of schizophrenia. The imaging findings support the view that striatal dysregulation of dopamine neurotransmission may be central to the disruption of neuronal networks and symptoms of schizophrenia.Īpart from the striatum, the dopamine subsystems also innervate several small brain structures in which there is a limited expression of dopaminergic markers, for instance the amygdala, the entorhinal cortex and subnuclei of the thalamus. Over the years, PET imaging has shown evidence for abnormalities in the brain dopaminergic system and that clinically useful treatments interact with dopamine receptors in the central nervous system. The dopamine system has since long been of central interest in schizophrenia research. Therefore, although some radiopharmaceuticals have the potential for clinical use in relation to mental disorders, none is actually used in the clinical practice. Moreover, most new radiopharmaceuticals require a new expensive specific module, in a hot cell. The infrastructure required to synthesize radiotracers is still complex, expensive and occupies a large space.Current PET/MRI scanners are extremely expensive, hampering a wide expansion of this technology.Even for processes localized within the amygdala, a part of the limbic system related to fear and anxiety, it is currently not possible to differentiate if they are occurring within the basolateral complex or the central nucleus. ![]() The standard PET/CT and the new PET/MRI whole body scanners result in a PET image resolution in the 4–5 mm FWHM range and, therefore, they are not optimized for imaging critical structures of the brain with dimensions of few millimetres. PET scanner resolution does not allow the visualization of brain critical structures. ![]()
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