Radiopharmaceuticals for PET and SPECT Imaging: A Literature Review over the Last Decade

Abstract

Positron emission tomography (PET) uses radioactive tracers and enables the functional imaging of several metabolic processes, blood flow measurements, regional chemical composition, and/or chemical absorption. Depending on the targeted processes within the living organism, different tracers are used for various medical conditions, such as cancer, particular brain pathologies, cardiac events, and bone lesions, where the most commonly used tracers are radiolabeled with 18F (e.g., [18F]-FDG and NA [18F]). Oxygen-15 isotope is mostly involved in blood flow measurements, whereas a wide array of 11C-based compounds have also been developed for neuronal disorders according to the affected neuroreceptors, prostate cancer, and lung carcinomas. In contrast, the single-photon emission computed tomography (SPECT) technique uses gamma-emitting radioisotopes and can be used to diagnose strokes, seizures, bone illnesses, and infections by gauging the blood flow and radio distribution within tissues and organs. The radioisotopes typically used in SPECT imaging are iodine-123, technetium-99m, xenon-133, thallium-201, and indium-111. This systematic review article aims to clarify and disseminate the available scientific literature focused on PET/SPECT radiotracers and to provide an overview of the conducted research within the past decade, with an additional focus on the novel radiopharmaceuticals developed for medical imaging.

LHRH conjugated gold nanoparticles assisted efficient ovarian cancer targeting evaluated via spectral photon-counting CT imaging: a proof-of-concept research

“…32 PET and SPECT are sensitive but are non-specific, need radioactive tracers and are relatively slower. 33 Several studies have indicated SPCCT as an emerging modality with potential to overcome the current imaging challenges. [34][35][36][37][38][39] SPCCT imaging benefits from an energy-discriminating photoncounting detector with high spatial and spectral resolution to differentiate and quantify multiple organic and inorganic components (biomarker labels, nanoparticles, calcium phosphate, lipid, water) in the target soft/hard tissue using a single scan plus postimage processing.…”

Skin Cancer Pathobiology at a Glance: A Focus on Imaging Techniques and Their Potential for Improved Diagnosis and Surveillance in Clinical Cohorts

“…As a result of recent advances in detector technologies and informatic processing algorithms, the spatial resolution of SPECT images is expected to approach that of PET images, without experiencing any decrease in sensitivity. Yet, the answer to the question concerning which technology will dominate the nuclear imaging field remains elusive [ 226 ]. At a glance, when compared to SPECT/CT, PET technology provides improved resolution and less attenuation and scatter artifacts and, therefore, superior imaging capabilities.…”

“…In order to achieve an increased sensitivity, PET generally operates with more versatile and reliable tracers, which come with exorbitant costs limiting the availability of PET imaging. In contrast, radiopharmaceuticals needed for SPECT are cheaper, have increased availability, and, due to the longer half-life of single photon emitters, display more effective targeting abilities of molecular targets of interest, allowing for an accurate imaging of the biological processes at equilibrium in vivo [ 226 ].…”

Neurospecific Molecules Measured in Periphery in Humans: How Do They Correlate with the Brain Levels? A Systematic Review

“…Scintigraphic quantification of radioisotopes distributed in the body after their infusion into the blood is the essence of PET and SPECT (gamma-emission), usually coupled with computer tomography (CT) or MRI. Both are increasingly used to estimate energy metabolism, blood flow, and chemical absorption (e.g., binding of brain receptors or transporters) but may also estimate a specific brain chemical (which is relevant to this review) in the case of development of an appropriate radioactive tracer [ 31 , 32 ]. While PET has the advantage of higher resolution and sensitivity, SPECT is more accessible and cheaper.…”