[F]FDG uptake in axillary lymph nodes and deltoid muscle after COVID-19 mRNA vaccination: a cohort study to determine incidence and contributing factors using a multivariate analysis.

Purpose: Reactive FDG uptake in the axillary lymph nodes (ALN) and deltoid muscle (DM) after COVID-19 mRNA vaccination has been recognized, although the actual situation in the Japanese population remains unknown. To determine the incidence of reactive FDG uptake and its contributing factors, we retrospectively studied a cohort of subjects who were vaccinated at our hospital.

Methods: Whole-body FDG-PET/CT examinations performed in 237 subjects out of 240 subjects with a definite history of COVID-19 vaccination (BNT162b2; BioNTech-Pfizer) were analyzed.

Adenosine A Receptor Occupancy by Caffeine After Coffee Intake in Parkinson's Disease.

Background: Coffee intake can decrease the risk for Parkinson's disease (PD). Its beneficial effects are allegedly mediated by caffeine through adenosine A receptor (A R) antagonist action.

Objective: We aimed to calculate occupancy rates of striatal A Rs by caffeine after coffee intake in PD.

Test-retest reproducibility of cerebral adenosine A receptor quantification using [C]preladenant.

Objective: To evaluate the reproducibility of cerebral adenosine A receptor (AR) quantification using [C]preladenant ([C]PLN) and PET in a test-retest study.

Methods: Eight healthy male volunteers were enrolled. Dynamic 90 min PET scans were performed twice at the same time of the day to avoid the effect of diurnal variation.

Synthesis and evaluation of N-isopropyl-p-[C]methylamphetamine as a novel cerebral blood flow tracer for positron emission tomography.

Introduction: Increases in fasting plasma glucose (PG) levels lead to a decrease in 2-deoxy-2-[F]fluoro-D-glucose ([F]FDG) uptake in the normal brain, especially in the precuneus, resulting in an Alzheimer's disease (AD)-like uptake pattern. Therefore, patients with higher PG levels, such as those with diabetes, can be erroneously diagnosed with AD when positron emission tomography (PET) imaging is done using [F]FDG, due to reduced uptake of [F]FDG in the precuneus. To help avoid an erroneous diagnosis of AD due to differences in glucose metabolism, evaluating cerebral blood flow (CBF) in the brain is useful.

Unchanged type 1 metabotropic glutamate receptor availability in patients with Alzheimer's disease: A study using C-ITMM positron emission tomography.

Imaging of type 1 metabotropic glutamate receptor (mGluR1) has recently become possible using positron emission tomography (PET). To date, little evidence exists on the role of mGluR1 in the pathophysiology of Alzheimer's disease (AD). We aimed to examine mGluR1 availability in patients with AD.

Pre-discard estimation of radioactivated materials in positron emission tomography cyclotron systems and concrete walls of a cyclotron vault.

Purpose: The concrete vault, cyclotron body, and peripheral equipment in a cyclotron room become radioactivated by neutrons generated by operating an unshielded cyclotron. Radionuclides and the amounts of radioactivated materials must be identified before discarding a cyclotron system. The present study aimed to reduce the amounts of concrete from cyclotron vaults, as well as cyclotron components and peripheral equipment, that will be disposed of as radioactivated waste by clarifying the nature and quantity of radioactivated materials remaining in facilities after cyclotron operations have ceased.

4-Borono-2-F-fluoro-L-phenylalanine PET for boron neutron capture therapy-oriented diagnosis: overview of a quarter century of research.

4-B-Borono-2-F-fluoro-L-phenylalanine (F-FBPA) was developed for monitoring the pharmacokinetics of 4-B-borono-L-phenylalanine (B-BPA) used in boron neutron capture therapy (BNCT) with positron emission tomography (PET). The tumor-imaging potential of F-FBPA was demonstrated in various animal models. Accumulation of F-FBPA was higher in melanomas than in non-melanoma tumors in animal models and cell cultures.

Occupancy of adenosine A receptors by istradefylline in patients with Parkinson's disease using C-preladenant PET.

Istradefylline, an adenosine A receptor (AR) antagonist, is effective as an adjunct to levodopa and can alleviate "off" time and motor symptoms in patients with Parkinson's disease (PD). The present study aimed to calculate occupancy rates of ARs by administrating istradefylline 20 mg or 40 mg, which is the currently approved dose for PD in Japan. Additionally, AR availability was compared between patients with PD and healthy controls.

Longitudinal effects of aging on F-FDG distribution in cognitively normal elderly individuals.

Previous studies of aging effects on fluorine-18-labeled fluorodeoxyglucose (F-FDG) distribution have employed cross-sectional designs. We examined aging effects on F-FDG distribution using both cross-sectional and longitudinal assessments. We obtained two F-FDG positron emission tomography scans at two different time points from 107 cognitively normal elderly participants.

Reliable radiosynthesis of 4-[B]borono-2-[F]fluoro-L-phenylalanine with quality assurance for boron neutron capture therapy-oriented diagnosis.

Objective: The aim of this study was to establish a reliable and routine method for the preparation of 4-[B]borono-2-[F]fluoro-L-phenylalanine (L-[F]FBPA) for boron neutron capture therapy-oriented diagnosis using positron emission tomography.

Methods: To produce L-[F]FBPA by electrophilic fluorination of 4-[B]borono-L-phenylalanine (L-BPA) with [F]acetylhypofluorite ([F]AcOF) via [F]F derived from the Ne(d,α)F nuclear reaction, several preparation parameters and characteristics of L-[F]FBPA were investigated, including: pre-irradiation for [F]F production, the carrier F content in the Ne target, L-BPA-to-F ratios, separation with high-performance liquid chromatography (HPLC) using 10 different eluents, enantiomeric purity, and residual trifluoroacetic acid used as the reaction solvent by gas chromatography-mass spectrometry.

Results: The activity yields and molar activities of L-[F]FBPA (n = 38) were 1200 ± 160 MBq and 46-113 GBq/mmol, respectively, after deuteron-irradiation for 2 h.

Age-Related Decrease in Male Extra-Striatal Adenosine A Receptors Measured C-MPDX PET.

Adenosine A receptors (ARs) are widely distributed throughout the entire human brain, while adenosine A receptors (ARs) are present in dopamine-rich areas of the brain, such as the basal ganglia. A past study using autoradiography reported a reduced binding ability of AR in the striatum of old rats. We developed positron emission tomography (PET) ligands for mapping the adenosine receptors and we successfully visualized the ARs using 8-dicyclopropylmethyl-1-C-methyl-3-propylxanthine (C-MPDX).

Changes in brain amyloid-β accumulation after donepezil administration.

Recent studies using the mouse model of Alzheimer's disease (AD) have shown that donepezil administration reduces brain amyloid-β (Aβ) accumulation. This study investigated whether donepezil administration can reduce brain Aβ accumulation in human patients with AD. Ten patients with AD underwent two C-Pittsburgh Compound B positron emission tomography sessions approximately one year apart to measure brain Aβ accumulation before and after donepezil treatment.

Effects of a novel tungsten-impregnated rubber neck shield on the quality of cerebral images acquired using O-labeled gas.

The present study aimed to validate the effects of a novel tungsten-impregnated rubber neck shield on the quality of phantom and clinical O-labeled gas positron emission tomography (PET) images. Images were acquired in the presence or absence of a neck shield from a cylindrical phantom containing [O]HO (phantom study) and from three individuals using [O]CO, [O]O and [O]CO gas (clinical study). Data were acquired in three-dimensional (3D) mode using a Discovery PET/CT 710.

Increased Binding Potential of Brain Adenosine A Receptor in Chronic Stages of Patients with Diffuse Axonal Injury Measured with [1-methyl-C] 8-dicyclopropylmethyl-1-methyl-3-propylxanthine Positron Emission Tomography Imaging.

The positron emission tomography (PET) radioligand for adenosine A receptor (A1R) [1-methyl-C] 8-dicyclopropylmethyl-1-methyl-3-propylxanthine (MPDX) has recently been developed for human brain imaging. In the present study, we evaluated the alteration of the A1R in patients with diffuse axonal injury (DAI) in chronic stage in vivo. Ten patients with DAI (7 men and 3 women) were included in this study.

Effects of glucose, insulin, and insulin resistance on cerebral 18F-FDG distribution in cognitively normal older subjects.

Background: Increasing plasma glucose levels and insulin resistance can alter the distribution pattern of fluorine-18-labeled fluorodeoxyglucose (18F-FDG) in the brain and relatively reduce 18F-FDG uptake in Alzheimer's disease (AD)-related hypometabolic regions, leading to the appearance of an AD-like pattern. However, its relationship with plasma insulin levels is unclear. We aimed to compare the effects of plasma glucose levels, plasma insulin levels and insulin resistance on the appearance of the AD-like pattern in 18F-FDG images.

Effects of exercise on brain activity during walking in older adults: a randomized controlled trial.

Background: Physical activity may preserve neuronal plasticity, increase synapse formation, and cause the release of hormonal factors that promote neurogenesis and neuronal function. Previous studies have reported enhanced neurocognitive function following exercise training. However, the specific cortical regions activated during exercise training remain largely undefined.

Age and gender effects of C-ITMM binding to metabotropic glutamate receptor type 1 in healthy human participants.

We examined possible age- and gender-related changes in binding of the selective antagonist N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-4-C-methoxy-N-methylbenzamide (C-ITMM) to metabotropic glutamate receptor type 1 in healthy human brains. Dynamic C-ITMM positron emission tomography scans (90 min) with serial arterial blood sampling were performed in 15 young and 24 older healthy adult volunteers. The total distribution volume (V) of several brain regions was estimated with 2-tissue compartment model analysis.

Adenosine A receptors measured with C-MPDX PET in early Parkinson's disease.

Adenosine A receptors (A Rs) interact negatively with dopamine D receptors (D Rs) in neurons of the basal ganglia's direct pathway, while adenosine A receptors (A Rs) negatively interact with dopamine D receptors (D Rs) in indirect-pathway neurons. The aim of this study was to investigate the cerebral density of A Rs in Parkinson's disease (PD) in its early stages, using PET scans with the radioligand 8-dicyclopropylmethyl-1- C-methyl-3-propylxanthine ( C-MPDX). We studied 10 drug-naïve patients with early PD.

Assessment of safety, efficacy, and dosimetry of a novel 18-kDa translocator protein ligand, [C]CB184, in healthy human volunteers.

Background: N,N-di-n-propyl-2-[2-(4-[C]methoxyphenyl)-6,8-dichloroimidazol[1,2-a]pyridine-3-yl]acetamide ([C]CB184) is a novel selective radioligand for the 18-kD translocator protein (TSPO), which is upregulated in activated microglia in the brain, and may be useful in positron emission tomography (PET). We examined the safety, radiation dosimetry, and initial brain imaging with [C]CB184 in healthy human volunteers.

Results: Dynamic [C]CB184 PET scans (90 min) were performed in five healthy male subjects.

Comparison of imaging using C-ITMM and F-FDG for the detection of cerebellar ataxia.

Unlabelled: Objective Newly developed methods for imaging type 1 metabotropic glutamate receptor (mGluR1) have the potential use for estimating cerebellar function. We aimed to compare mGluR1 imaging using N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-4-C-methoxy-N-methylbenzamide (C-ITMM) with the existing marker, fluorine-18-labeled fluorodeoxyglucose (F-FDG) imaging, in the cerebellum.

Methods: Fourteen subjects consisting of 12 patients with cerebellar ataxia and two healthy subjects underwent C-ITMM and F-FDG positron emission tomography.

Initial Evaluation of an Adenosine A Receptor Ligand, C-Preladenant, in Healthy Human Subjects.

C-preladenant is a selective antagonist for mapping of cerebral adenosine A receptors (ARs) by PET. This is a first-in-human study to examine the safety, radiation dosimetry, and brain imaging of C-preladenant in healthy human subjects. Dynamic C-preladenant PET scans (90 min) were obtained in 5 healthy male subjects.

The neural substrate of gait and executive function relationship in elderly women: A PET study.

Aim: Understanding the relationship between age-related gait impairment, such as slow gait, and executive functioning in seniors may help identify individuals at higher risk of mobility decline, falls, and progression to dementia at earlier stages. We aim to identify brain regions concomitantly associated with poor gait and executive functioning in a cohort of well-functioning elderly women.

Methods: In total, 149 well-functioning women aged 70.

Potential Therapeutic Applications of Adenosine A Receptor Ligands and Opportunities for A Receptor Imaging.

Adenosine A receptors (A Rs) are highly expressed in the human striatum, and at lower densities in the cerebral cortex, the hippocampus, and cells of the immune system. Antagonists of these receptors are potentially useful for the treatment of motor fluctuations, epilepsy, postischemic brain damage, or cognitive impairment, and for the control of an immune checkpoint during immunotherapy of cancer. A R agonists may suppress transplant rejection and graft-versus-host disease; be used to treat inflammatory disorders such as asthma, inflammatory bowel disease, and rheumatoid arthritis; be locally applied to promote wound healing and be employed in a strategy for transient opening of the blood-brain barrier (BBB) so that therapeutic drugs and monoclonal antibodies can enter the brain.

Central μ-Opioidergic System Activation Evoked by Heavy and Severe-Intensity Cycling Exercise in Humans: a Pilot Study Using Positron Emission Tomography with 11C-Carfentanil.

The central opioid receptor system likely contributes to the mechanism underlying the changes in affect elicited by exercise. Our aim was to use positron emission tomography (PET) to test whether exercise intensity influences activation of the μ-opioid receptor system in the brain, and whether changes in opioid receptor activation correlate with exercise-induced changes in affect. 7 healthy young male subjects (23±2 years) performed 20-min constant-load cycling exercises at heavy (ExH) and severe-intensity (ExS), and PET was performed using [C]carfentanil as a tracer before and after each exercise.