Potential application of [F]AlF-PSMA-11 PET/CT in radioiodine refractory thyroid carcinoma.

Background: Patients diagnosed with radioiodine refractory (RAI-R) thyroid carcinoma (TC) have a significantly worse prognosis than patients with radiosensitive TC. These refractory malignancies are often dedifferentiated, hindering the effectiveness of iodine-based imaging. Additionally, the role of metabolic imaging using [F]FDG PET/CT is also limited in these cases, making adequate staging of RAI-R TC challenging.

F-PSMA-11 Versus Ga-PSMA-11 Positron Emission Tomography/Computed Tomography for Staging and Biochemical Recurrence of Prostate Cancer: A Prospective Double-blind Randomised Cross-over Trial.

Background: Fluorine-18 (F)-labelled prostate-specific membrane antigen (PSMA) offers several advantages over gallium-68 (Ga) in terms of costs, yield, transport/distribution, and image resolution.

Objective: This trial investigates the new radiotracer F-PSMA-11 via a prospective, intraindividual crossover design. The trial was powered for noninferiority of F-PSMA-11 over Ga-PSMA-11 positron emission tomography (PET)/computed tomography (CT) in terms of the number of positive PET scans.

Impact of F-PSMA-11 PET/CT on Management of Biochemical Recurrence and High-Risk Prostate Cancer Staging : F-PSMA-11 PET/CT and Impact on Prostate Cancer Management.

Purpose: In this study, we evaluated the impact of F-PSMA-11 PET/CT on the patient management plan in patients with primary or recurrent disease. Furthermore, a correlation between PET findings and other modalities was performed.

Procedures: In this prospective observational study, 60 prostate cancer patients (9 primary staging, 51 biochemical recurrence) were imaged with F-PSMA-11 PET/CT.

Accelerated HF-rTMS Modifies SERT Availability in the Subgenual Anterior Cingulate Cortex: A Canine [C]DASB Study on the Serotonergic System.

Repetitive transcranial magnetic stimulation (rTMS) is thought to partly exert its antidepressant action through the serotonergic system. Accelerated rTMS may have the potential to result in similar but faster onset of clinical improvement compared to the classical daily rTMS protocols, but given that delayed clinical responses have been reported, the neurobiological effects of accelerated paradigms remain to be elucidated including on this neurotransmitter system. This sham-controlled study aimed to evaluate the effects of accelerated high frequency rTMS (aHF-rTMS) over the left frontal cortex on the serotonin transporter (SERT) in healthy beagle dogs.

Intra-individual dynamic comparison of F-PSMA-11 and Ga-PSMA-11 in LNCaP xenograft bearing mice.

Recently, a F-labeled derivative of the widely used Ga-PSMA-11 was developed for PET imaging of prostate cancer. Although F-PSMA-11 has already been evaluated in a Phase I and Phase II clinical trial, preclinical evaluation of this radiotracer is important for further understanding its dynamic behavior. Saturation binding experiments were conducted by incubation of LNCaP cells with F-PSMA-11 or Ga-PSMA-11 for 1 h, followed by determination of the specific and aspecific binding.

Optimization of PET protocol and interrater reliability of F-PSMA-11 imaging of prostate cancer.

Background: Several scan parameters for PET imaging with F-PSMA-11 such as dosage, acquisition time and scan duration were evaluated to determine the most appropriate scan protocol, as well as the effect of furosemide administration on lesion visualization. Forty-four patients were randomly assigned to a dosage group (2.0 ± 0.

Radiation Dosimetry and Biodistribution of F-PSMA-11 for PET Imaging of Prostate Cancer.

Prostate-specific membrane antigen (PSMA) is highly overexpressed in prostate cancer. Many PSMA analog radiotracers for PET/CT prostate cancer staging have been developed, such as Ga-PSMA-11. This radiotracer has achieved good results in multiple clinical trials, but because of the superior imaging characteristics of F-fluoride, F-PSMA-11 was developed.

Regional alterations of cerebral [F]FDG metabolism in the chronic unpredictable mild stress- and the repeated corticosterone depression model in rats.

Preclinical research has been indispensable in the exploration of the neurological basis of major depressive disorder (MDD). The present study aimed to examine effects on regional brain activity of two frequently used depression models, the chronic unpredictable mild stress (CUMS)- and the chronic corticosterone (CORT) depression model. The CUMS and CORT depression model were induced by exposing male Long-Evans rats to a 4-week procedure of unpredictable mild stressors or a 3-week procedure of chronic corticosterone, respectively.

Anaesthesia, not number of sessions, influences the magnitude and duration of an aHF-rTMS in dogs.

Background: Currently, the rat has been a useful animal model in brain stimulation research. Nevertheless, extrapolating results from rodent repetitive Transcranial Magnetic Stimulation (rTMS) research to humans contains several hurdles. This suggests the desperate need for a large animal model in translational rTMS research.

Accurate external localization of the left frontal cortex in dogs by using pointer based frameless neuronavigation.

Background: In humans, non-stereotactic frameless neuronavigation systems are used as a topographical tool for non-invasive brain stimulation methods such as Transcranial Magnetic Stimulation (TMS). TMS studies in dogs may provide treatment modalities for several neuropsychological disorders in dogs. Nevertheless, an accurate non-invasive localization of a stimulation target has not yet been performed in this species.

Estimation of the optimal dosing regimen of escitalopram in dogs: A dose occupancy study with [11C]DASB.

Although the favourable characteristics of escitalopram as being the most selective serotonin reuptake inhibitor and having an increased therapeutic efficacy via binding on an additional allosteric binding site of the serotonin transporter, its dosing regimen has not yet been optimized for its use in dogs. This study aimed to estimate the optimal dosing frequency and the required dose for achieving 80% occupancy of the serotonin transporters in the basal ganglia. The dosing frequency was investigated by determining the elimination half-life after a four day oral pre-treatment period with 0.

In Vivo Evaluation of Blood Based and Reference Tissue Based PET Quantifications of [11C]DASB in the Canine Brain.

This first-in-dog study evaluates the use of the PET-radioligand [11C]DASB to image the density and availability of the serotonin transporter (SERT) in the canine brain. Imaging the serotonergic system could improve diagnosis and therapy of multiple canine behavioural disorders. Furthermore, as many similarities are reported between several human neuropsychiatric conditions and naturally occurring canine behavioural disorders, making this tracer available for use in dogs also provide researchers an interesting non-primate animal model to investigate human disorders.

In vivo quantification of the [(11)C]DASB binding in the normal canine brain using positron emission tomography.

Background: [(11)C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile ([(11)C]DASB) is currently the mostly used radiotracer for positron emission tomography (PET) quantitative studies of the serotonin transporter (SERT) in the human brain but has never been validated in dogs. The first objective was therefore to evaluate normal [(11)C]DASB distribution in different brain regions of healthy dogs using PET. The second objective was to provide less invasive and more convenient alternative methods to the arterial sampling-based kinetic analysis.

Correlation between individual differences in striatal dopamine and in visual consciousness.

A widely held view on consciousness is that it is related to the 'broadcasting' of sensory information to the whole brain [1-3]. Despite the fact that there is general support for this view, it remains unclear how exactly this broadcasting is established. It has been proposed [2,3] that thalamocortical circuits are an important mediator of such broadcasting, but empirical support for this claim is lacking.

Radiochemistry devoted to the production of monoamine oxidase (MAO-A and MAO-B) ligands for brain imaging with positron emission tomography.

Monoamine oxidase (MAO) belongs to a family of flavin-containing integral enzymes that are present in the outer mitochondrial membrane in neurons and glial cells in the central nervous system. These enzymes catalyze the oxidative deamination of various neurotransmitters, biogenic amines, and xenobiotics, thereby influencing their availability and physiological activity in brain and body. Over the past decades, many potential positron emission tomography tracers have been put forward to visualize MAO in the brain with varying success, and recent publications on the topic illustrate the continuing interest in the field.

Improved HPLC purification strategy for [11C]raclopride and [11C]DASB leading to high radiochemical yields and more practical high quality radiopharmaceutical formulations.

A downscaled analytical HPLC purification strategy for [(11)C]raclopride and [(11)C]DASB was proposed to obtain a straightforward produced injectable solution with a substantially reduced volume. Both tracers were radiosynthesized using [(11)C]methyl triflate, and several analytical columns, in combination with ethanol containing eluents, were examined to optimize the chromatographic resolution. This resulted in a 5 mL solution of [(11)C]raclopride, obtained after 6 min, and a 7 mL solution of [(11)C]DASB, obtained after 10 min, using a C16-alkylamide and CN column respectively.