Advances in CNS Imaging Agents: Focus on PET and SPECT Tracers in Experimental and Clinical Use

Abstract

The physiological functioning of the brain is not well-known in current day medicine and the pathologies of many neuropsychiatric disorders are still not yet fully understood. With our aging population and better life expectancies, it has become imperative to find better biomarkers for disease progression as well as receptor target engagements. In the last decade, these major advances in the field of molecular CNS imaging have been made available with tools such as functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), single photon emission computed tomography (SPECT), and neuroreceptor-targeted positron emission tomography (PET). These tools have given researchers, pharmaceutical companies, and clinical physicians a better method of understanding CNS dysfunctions, and the ability to employ improved therapeutic agents. This review is intended to provide an update on brain imaging agents that are currently used in clinical and translational research toward treatment of CNS disorders. The review begins with amyloid and tau imaging, the former of which has at least three [(18)F] agents that have been recently approved and will soon be available for clinical use for specific indications in the USA and elsewhere. Other prevalent PET and SPECT neurotransmitter system agents, including those newly US FDA-approved imaging agents related to the dopaminergic system, are included. A review of both mature and potentially growing PET imaging agents, including those targeting serotonin and opiate receptor systems, is also provided.

Tau imaging with [18F]THK‐5351 in progressive supranuclear palsy

“…To elucidate the neurodegenerative mechanisms, imaging technology has been developed to identify these misfolded and aggregated proteins in living patients. For over a decade, positron emission tomography (PET) imaging has allowed visualization of amyloid plaques with Aβ‐PET tracers, such as Pittsburgh compound B (PIB) among others . Recently, several tau imaging radiotracers have been developed and used in clinical studies .…”

Nuclear Medicine in Times of COVID-19: How Radiopharmaceuticals Could Help to Fight the Current and Future Pandemics

“…A particular advantage of these techniques is that only tracer quantities of a radiolabeled drug need to be administered for PK and ADME studies, so that they can be performed early (i.e., before phase I trials) in patients [63,64]. For a more detailed description of nuclear imaging techniques and their many applications, the reader is referred to several previous reviews on the topic [58,60,[65][66][67].…”

Biomarkers of Brain Structure and Function for Neurodegenerative Disorders: Are They Adequate for Go/No Go Decisions in Drug Development?

“…Beyond ligands that bind to receptors to which drugs are targeted, there are those such as [ 18 F] florbatepir, recently approved by the US Food and Drug Administration (FDA) as a clinical imaging agent, which bind to substances, in this case amyloid, in the brain that can be used to selection of patients for drug trials . Such ligands can also be used to assess drug effects on the substance in question.…”