Psychiatric disorders

In the field of psychiatry, positron emission tomography (PET) imaging has attracted interest of researchers in a broad spectrum of diseases, such as depression, anxiety disorders, schizophrenia, and impulse control disorders. Being able to provide quantitative measurements of glucose metabolism, perfusion, and neurotransmitter functionality (e.g., neuroreceptors, transporters), PET provides useful information which adds to the differential diagnosis of diseases, as well as to understanding the neurobiological basis and determining neurotransmitter impairments. Functional imaging may further help to establish novel concepts and theoretic frameworks regarding diseases and to provide a rationale for specific pharmacological treatment. In psychiatric drug development, PET may play a role in the pharmacokinetic evaluation of a drug and in receptor occupancy studies, which helps to determine optimal dosing for further clinical trials. Finally, PET measurements may function as a biomarker, which could improve the selection of subjects entering clinical trials and provide an additional means of response evaluation. With the arrival of hybrid imaging, such as PET/CT and PET/MRI, simultaneous anatomical and functional biomarkers are obtained, which may be complementary in selected cases. Recent developments in functional MRI allow for different imaging combinations, such as the combined studies of cerebral perfusion and neurotransmitter systems. In this chapter, we will address the role of PET and anatomical imaging in various psychiatric disorders, with a particular focus on the separate PET and MRI findings and on potential applications of hybrid imaging.