Feasibility Study of a Time-of-Flight Brain Positron Emission Tomography Employing Individual Channel Readout Electronics

The purpose of this study was to investigate the feasibility of a time-of-flight (TOF) brain positron emission tomography (PET) providing high-quality images. It consisted of 30 detector blocks arranged in a ring with a diameter of 257 mm and an axial field of view of 52.2 mm. Each detector block was composed of two detector modules and two application-specific integrated circuit (ASIC) chips. The detector module was composed of an 8 × 8 array of 3 × 3 mm2 multi-pixel photon counters and an 8 × 8 array of 3.11 × 3.11 × 15 mm3 lutetium yttrium oxyorthosilicate scintillators. The 64-channel individual readout ASIC was used to acquire the position, energy, and time information of a detected gamma ray. A coincidence timing resolution of 187 ps full width at half maximum (FWHM) was achieved using a pair of channels of two detector modules. The energy resolution and spatial resolution were 6.6 ± 0.6% FWHM (without energy nonlinearity correction) and 2.5 mm FWHM, respectively. The results of this study demonstrate that the developed TOF brain PET could provide excellent performance, allowing for a reduction in radiation dose or scanning time for brain imaging due to improved sensitivity and signal-to-noise ratio.

Kinetics and 28-day test–retest repeatability and reproducibility of [11C]UCB-J PET brain imaging

[11C]UCB-J is a novel radioligand that binds to synaptic vesicle glycoprotein 2A (SV2A). The main objective of this study was to determine the 28-day test–retest repeatability (TRT) of quantitative [11C]UCB-J brain positron emission tomography (PET) imaging in Alzheimer’s disease (AD) patients and healthy controls (HCs). Nine HCs and eight AD patients underwent two 60 min dynamic [11C]UCB-J PET scans with arterial sampling with an interval of 28 days. The optimal tracer kinetic model was assessed using the Akaike criteria (AIC). Micro-/macro-parameters such as tracer delivery (K1) and volume of distribution (VT) were estimated using the optimal model. Data were also analysed for simplified reference tissue model (SRTM) with centrum semi-ovale (white matter) as reference region. Based on AIC, both 1T2k_VB and 2T4k_VB described the [11C]UCB-J kinetics equally well. Analysis showed that whole-brain grey matter TRT for VT, DVR and SRTM BPND were –2.2% ± 8.5, 0.4% ± 12.0 and –8.0% ± 10.2, averaged over all subjects. [11C]UCB-J kinetics can be well described by a 1T2k_VB model, and a 60 min scan duration was sufficient to obtain reliable estimates for both plasma input and reference tissue models. TRT for VT, DVR and BPND was <15% (1SD) averaged over all subjects and indicates adequate quantitative repeatability of [11C]UCB-J PET.

A New Positron Emission Tomography Probe for Orexin Receptors Neuroimaging

The orexin receptor (OX) is critically involved in motivation and sleep−wake regulation and holds promising therapeutic potential in various mood disorders. To further investigate the role of orexin receptors (OXRs) in the living human brain and to evaluate the treatment potential of orexin-targeting therapeutics, we herein report a novel PET probe ([11C]CW24) for OXRs in the brain. CW24 has moderate binding affinity for OXRs (IC50 = 0.253 μM and 1.406 μM for OX1R and OX2R, respectively) and shows good selectivity to OXRs over 40 other central nervous system (CNS) targets. [11C]CW24 has high brain uptake in rodents and nonhuman primates, suitable metabolic stability, and appropriate distribution and pharmacokinetics for brain positron emission tomography (PET) imaging. [11C]CW24 warrants further evaluation as a PET imaging probe of OXRs in the brain.

Brain positron emission tomography with 2-18F-2-deoxi-D-glucose of patients with dystonia and essential tremor detects differences between these disorders

We studied patients with dystonia (D) and essential tremor (ET) using positron emission tomography (PET) equipped with Cortex ID software. This allowed PET brain visualisation to be compared to scans of a control group by means of the z-score. The study revealed hypo-metabolism in both D and ET groups, and additionally revealed a difference between these two groups of patients in certain areas of the brain. These two nosological forms overlap in clinical features and are difficult to differentiate. The PET picture may help to provide a differential diagnosis in addition to the biochemical difference in dopamine exchange previously revealed by us in this group of patients.