SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Positron

198

Because curcumin’s anti-inflammatory properties may protect the brain from neurodegeneration, we studied its effect on memory in non-demented adults and explored its impact on brain amyloid and tau accumulation using 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile positron emission tomography (FDDNP-PET).

Concepts: Neurology, Carbon-11, Fluorine-18, Hippocampus, Positron emission, Positron, Alzheimer's disease, Positron emission tomography

168

Positron emission tomography (PET) with (15)O tracers provides essential information in patients with cerebral vascular disorders, such as cerebral blood flow (CBF), oxygen extraction fraction (OEF), and metabolic rate of oxygen (CMRO(2)). However, most of techniques require an additional C(15)O scan for compensating cerebral blood volume (CBV). We aimed to establish a technique to calculate all functional images only from a single dynamic PET scan, without losing accuracy or statistical certainties. The technique was an extension of previous dual-tracer autoradiography (DARG) approach, but based on the basis function method (DBFM), thus estimating all functional parametric images from a single session of dynamic scan acquired during the sequential administration of H(2)(15)O and (15)O(2). Validity was tested on six monkeys by comparing global OEF by PET with those by arteriovenous blood sampling, and tested feasibility on young healthy subjects. The mean DBFM-derived global OEF was 0.57±0.06 in monkeys, in an agreement with that by the arteriovenous method (0.54±0.06). Image quality was similar and no significant differences were seen from DARG; 3.57%±6.44% and 3.84%±3.42% for CBF, and -2.79%±11.2% and -6.68%±10.5% for CMRO(2). A simulation study demonstrated similar error propagation between DBFM and DARG. The DBFM method enables accurate assessment of CBF and CMRO(2) without additional CBV scan within significantly shortened examination period, in clinical settings.Journal of Cerebral Blood Flow & Metabolism advance online publication, 12 December 2012; doi:10.1038/jcbfm.2012.188.

Concepts: Functional magnetic resonance imaging, Medical imaging, Carbon-11, Positron emission, Metabolism, Fluorine-18, Positron, Positron emission tomography

168

Fever of unknown origin is a diagnostic challenge. Among its causes are of large caliber vessels vasculitis (LCVV), including Takayasu arteritis (TA) and giant cell arteritis (GCA). Early diagnosis is vital to prevent fibrosis of the vessel wall, and consequently, stenoses, aneurysms or occlusions. Imaging techniques can be of great help in recent years, highlighting the temporal artery through ultrasound, MRI and PET-CT.

Concepts: Arteritis, Blood vessel, Positron, Takayasu's arteritis, Radiology, Giant cell arteritis, Positron emission tomography, Medical imaging

158

Since prostate-specific membrane antigen (PSMA) has been identified as a diagnostic target for prostate cancer, many urea-based small PSMA-targeting molecules were developed. First, the clinical application of these Ga-68 labelled compounds in positron emission tomography (PET) showed their diagnostic potential. Besides, the therapy of prostate cancer is a demanding field, and the use of radiometals with PSMA bearing ligands is a valid approach. In this work, we describe the synthesis of a new PSMA ligand, CHX-A'‘-DTPA-DUPA-Pep, the subsequent labelling with Ga-68, Lu-177 and Y-90 and the first in vitro characterization. In cell investigations with PSMA-positive LNCaP C4-2 cells, KD values of ≤14.67 ± 1.95 nM were determined, indicating high biological activities towards PSMA. Radiosyntheses with Ga-68, Lu-177 and Y-90 were developed under mild reaction conditions (room temperature, moderate pH of 5.5 and 7.4, respectively) and resulted in nearly quantitative radiochemical yields within 5 min.

Concepts: Fluorine-18, Positron emission, Metastasis, Cancer, Positron, Prostate specific membrane antigen, Prostate cancer, Positron emission tomography

147

Quantitative measurements of change in β-amyloid load from Positron Emission Tomography (PET) images play a critical role in clinical trials and longitudinal observational studies of Alzheimer’s disease. These measurements are strongly affected by methodological differences between implementations, including choice of reference region and use of partial volume correction, but there is a lack of consensus for an optimal method. Previous works have examined some relevant variables under varying criteria, but interactions between them prevent choosing a method via combined meta-analysis. In this work, we present a thorough comparison of methods to measure change in β-amyloid over time using Pittsburgh Compound B (PiB) PET imaging.

Concepts: Clinical trial, Fluorine-18, Pittsburgh compound B, Measurement, Positron, Scientific method, Alzheimer's disease, Positron emission tomography

141

18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and PET/CT have become two of the most powerful tools for malignant lymphoma exploration, but their diagnostic role in primary central nervous system lymphoma (PCNSL) is still disputed. The purpose of our study is to identify the usefulness of 18F-FDG PET and PET/CT for detecting PCNSL.

Concepts: Fludeoxyglucose, Primary central nervous system lymphoma, Positron, Lymphoma, Brain, Central nervous system, Nervous system, Positron emission tomography

140

The aim of this study was to develop a dual-modality positron emission tomography/magnetic resonance (PET/MR) imaging probe by radiolabeling gadolinium-containing AGuIX derivatives with the positron-emitter Gallium-68 ((68)Ga).

Concepts: Positron emission tomography, Radiation therapy, Positron, Medicine, Electron

139

Photoluminescence (PL) was used to estimate the concentration of point defects in GaN. The results are compared with data from positron annihilation spectroscopy (PAS), secondary ion mass spectrometry (SIMS), and deep level transient spectroscopy (DLTS). Defect-related PL intensity in undoped GaN grown by hydride vapor phase epitaxy increases linearly with the concentration of related defects only up to 10(16) cm(-3). At higher concentrations, the PL intensity associated with individual defects tends to saturate, and accordingly, does not directly correlate with the concentration of defects. For this reason, SIMS analysis, with relatively high detection limits, may not be helpful for classifying unidentified point defects in GaN. Additionally, we highlight challenges in correlating defects identified by PL with those by PAS and DLTS methods.

Concepts: Electron, Epitaxy, Secondary ion mass spectrometry, Phase diagram, Positron, Deep-level transient spectroscopy, Analytical chemistry, Spectroscopy

113

To demonstrate the use of (18)Fluorodeoxyglucose positron emission tomography (PET) and magnetic resonance imaging (MRI) in combination ((18)FDG-PET) to assess the metabolic activity of ACL graft tissue and evaluate the utility of this technique for ligament imaging.

Concepts: Helium, Positron, Nuclear magnetic resonance, Spin, Magnetic resonance imaging, Radiology, Medical imaging, Positron emission tomography

100

Alzheimer’s disease (AD) is currently incurable, but there is general agreement that a minimally invasive blood biomarker for screening in preclinical stages would be crucial for future therapy. Diagnostic tools for detection of AD are either invasive like cerebrospinal fluid (CSF) biomarkers or expensive such as positron emission tomography (PET) scanning. Here, we determine the secondary structure change of amyloid-β (Aβ) in human blood. This change used as blood amyloid biomarker indicates prodromal AD and correlates with CSF AD biomarkers and amyloid PET imaging in the cross-sectional BioFINDER cohort. In a further population-based longitudinal cohort (ESTHER), the blood biomarker detected AD several years before clinical diagnosis in baseline samples with a positive likelihood ratio of 7.9; that is, those who were diagnosed with AD over the years were 7.9 times more likely to test positive. This assay may open avenues for blood screening of early AD stages as a funnel for further more invasive and expensive tests.

Concepts: Medical tests, Medical imaging, Positron emission, Fluorine-18, Neuroimaging, Positron, Alzheimer's disease, Positron emission tomography