[PET imaging for better understanding of normal and pathological neurotransmission]. / L'imagerie TEP pour une meilleure compréhension de la neurotransmission normale et pathologique.

Positron emission tomography imaging is still an expanding field of preclinical and clinical investigations exploring the brain and its normal and pathological functions. In addition to technological improvements in PET scanners, the availability of suitable radiotracers for unexplored pharmacological targets is a key factor in this expansion. Many radiotracers (or radiopharmaceuticals, when administered to humans) have been developed by multidisciplinary teams to visualize and quantify a growing numbers of brain receptors, transporters, enzymes and other targets. The development of new PET radiotracers still represents an exciting challenge, given the large number of neurochemical functions that remain to be explored. In this article, we review the development context of the first preclinical radiotracers and their passage to humans. The main current contributions of PET radiotracers are described in terms of imaging neuronal metabolism, quantification of receptors and transporters, neurodegenerative and neuroinflammatory imaging. The different approaches to functional imaging of neurotransmission are also discussed. Finally, the contributions of PET imaging to the research and development of new brain drugs are described.

TITLE: L'imagerie TEP pour une meilleure compréhension de la neurotransmission normale et pathologique. ABSTRACT: La neuroimagerie des récepteurs cérébraux a commencé au début des années 1980. Aujourd'hui, quelque quarante ans plus tard, l'imagerie par tomographie d'émission de positons (TEP) est toujours un domaine en expansion dans les études précliniques et cliniques cherchant à explorer le cerveau et son fonctionnement normal et pathologique. Outre les améliorations apportées aux caméras TEP et à l'analyse d'images, la disponibilité de radiotraceurs est un facteur déterminant de cette expansion. De nombreux radiotraceurs (ou radiopharmaceutiques, lorsque injectés chez l'Homme) ont été mis au point par des équipes pluridisciplinaires pour visualiser et quantifier un nombre croissant de récepteurs, transporteurs, enzymes et autres cibles moléculaires du cerveau. Le développement de nouveaux radiotraceurs TEP représente un défi passionnant, du fait du grand nombre de cibles et de fonctions neurochimiques qui restent encore à explorer. Dans cet article, nous resituons le contexte de développement des premiers radiotraceurs précliniques et leur passage à l'Homme. Les principales contributions actuelles des radiotraceurs TEP sont décrites en termes d'imagerie du métabolisme neuronal, de quantification des récepteurs et des transporteurs, d'imagerie neurodégénérative et neuroinflammatoire. Les différentes approches d'imagerie fonctionnelle de la neurotransmission sont également abordées. Enfin, les apports de l'imagerie TEP à la recherche et au développement de nouveaux médicaments du cerveau sont décrits.

Classics in Neuroimaging: Imaging the Dopaminergic Pathway with PET.

The success of positron emission tomography (PET) for observing molecular processes underlying brain function and disease is underpinned by radiotracer chemistry. From the earliest applications of PET to measure dopamine synthesis capacity and the abundance of neuroreceptors and transporters, to the more recent topic of dynamic neurochemical imaging, interrogation of brain dopamine in conditions such as neurodegenerative diseases, schizophrenia, mood disorders, and addictions has been a driving force that challenges the ingenuity of radiopharmaceutical scientists. In fact, the pursuit of new ligands and reaction methods to address longstanding challenges has often been pioneered in the context of dopamine imaging. From this viewpoint, we highlight the unique history of imaging the dopaminergic pathway with PET, and present our interpretation of how this worldwide effort shaped and continues to drive the field of molecular imaging.

Historic images in nuclear medicine: 1976: the first issue of clinical nuclear medicine and the first human FDG study.

In 1976, 2 major molecular imaging events coincidentally took place: Clinical Nuclear Medicine was first published in June, and in August researchers at the Hospital of the University of Pennsylvania created the first images in humans with F-FDG. FDG was initially developed as part of an evolution set in motion by fundamental research studies with positron-emitting tracers in the 1950s by Michel Ter-Pegossian and coworkers at the Washington University. Today, Clinical Nuclear Medicine is a valued scientific contributor to the molecular imaging community, and FDG PET is considered the backbone of this evolving and exciting discipline.

Nuclear medicine procedures in the diagnosis of NET: a historical perspective.

Novel diagnostic tools and therapies have emerged as a result of the continuous endeavors relating to neuroendocrine tumors (NETs). Nuclear medicine plays a pivotal role in the imaging and treatment of NETs. Somatostatin receptor analogues and metaiodobenzylguanidine remain front-line single-photon emission computed tomography (SPECT) radiotracers in the imaging of NET; their utility has been augmented by the increasing availability of SPECT/CT. Positron emission tomography has been growing rapidly in the imaging of NETs, paralleled by great efforts toward the development of new tracers. Hybrid imaging will play an important role in the future of NETs.