Liquid Xenon Detectors for Positron Emission Tomography

PET is a functional imaging technique based on detection of annihilation photons following beta decay producing positrons. In this paper, we present the concept of a new PET system for preclinical applications consisting of a ring of twelve time projection chambers filled with liquid xenon viewed by avalanche photodiodes. Simultaneous measurement of ionization charge and scintillation light leads to a significant improvement to spatial resolution, image quality, and sensitivity. Simulated performance shows that an energy resolution of <10% (FWHM) and a sensitivity of 15% are achievable. First tests with a prototype TPC indicate position resolution <1 mm (FWHM).Comment: Paper presented at the International Nuclear Physics Conference, Vancouver, Canada, 201

Measuring dopaminergic function in the 6-OHDA-lesioned rat: a comparison of PET and microdialysis

BACKGROUND: [(18) F]fluorodopa (FDOPA) positron emission tomography (PET) allows assessment of levodopa (LDOPA) metabolism and is widely used to study Parkinson's disease. We examined how [(18) F]FDOPA PET-derived kinetic parameters relate the dopamine (DA) and DA metabolite content of extracellular fluid measured by microdialysis to aid in the interpretation of data from both techniques. METHODS: [(18) F]FDOPA PET imaging and microdialysis measurements were performed in unilaterally 6-hydroxydopamine-lesioned rats (n = 8) and normal control rats (n = 3). Microdialysis testing included baseline measurements and measurements following acute administration of LDOPA. PET imaging was also performed using [(11)C]dihydrotetrabenazine (DTBZ), which is a ligand for the vesicular monoamine transporter marker and allowed assessment of denervation severity. RESULTS: The different methods provided highly correlated data. Lesioned rats had reduced DA metabolite concentrations ipsilateral to the lesion (p < 0.05 compared to controls), with the concentration being correlated with FDOPA's effective distribution volume ratio (EDVR; r = 0.86, p < 0.01) and DTBZ's binding potential (BP(ND); r = 0.89, p < 0.01). The DA metabolite concentration in the contralateral striatum of severely (>80%) lesioned rats was lower (p < 0.05) than that of less severely lesioned rats (<80%) and was correlated with the ipsilateral PET measures (r = 0.89, p < 0.01 for BP(ND)) but not with the contralateral PET measures. EDVR and BP(ND) in the contralateral striatum were not different from controls and were not correlated with the denervation severity. CONCLUSIONS: The demonstrated strong correlations between the PET and microdialysis measures can aid in the interpretation of [(18) F]FDOPA-derived kinetic parameters and help compare results from different studies. The contralateral striatum was affected by the lesioning and so cannot always serve as an unaffected control

Is axonal degeneration a key early event in Parkinson’s disease?

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of IOS Press for personal use, not for redistribution. The definitive version was published in Journal of Parkinson's Disease 6 (2016): 703-707, doi:10.3233/JPD-160881.Recent research suggests that in Parkinson’s disease the long, thin and unmyelinated axons of dopaminergic neurons degenerate early in the disease process. We organized a workshop entitled ‘Axonal Pathology in Parkinson’s disease’, on March 23rd, 2016, in Cleveland, Ohio with the goals of summarizing the state-of-the-art and defining key gaps in knowledge. A group of eight research leaders discussed new developments in clinical pathology, functional imaging, animal models, and mechanisms of degeneration including neuroinflammation, autophagy and axonal transport deficits. While the workshop focused on PD, comparisons were made to other neurological conditions where axonal degeneration is well recognized

Movement Disorders in the World of COVID-19

Resumen no disponibleFil: Merello, Marcelo. Fleni. Departamento de Neurología. Servicio de Movimientos Anormales; Argentina.Fil: Stoessl, A Jon. Pacific Parkinson's Research Centre & Djavad Mowafaghian Centre for Brain Health University of British Columbia; Canadá.Fil: Bhatia, Kailash P. UCL Queen Square Institute of Neurology London. Department of Clinical and Movement Neurosciences; Reino Unido

Different pieces of the same puzzle : a multifaceted perspective on the complex biological basis of Parkinson’s disease

The biological basis of the neurodegenerative movement disorder, Parkinson’s disease (PD), is still unclear despite it being ‘discovered’ over 200 years ago in Western Medicine. Based on current PD knowledge, there are widely varying theories as to its pathobiology. The aim of this article was to explore some of these different theories by summarizing the viewpoints of laboratory and clinician scientists in the PD field, on the biological basis of the disease. To achieve this aim, we posed this question to thirteen “PD experts” from six continents (for global representation) and collated their personal opinions into this article. The views were varied, ranging from toxin exposure as a PD trigger, to LRRK2 as a potential root cause, to toxic alpha-synuclein being the most important etiological contributor. Notably, there was also growing recognition that the definition of PD as a single disease should be reconsidered, perhaps each with its own unique pathobiology and treatment regimen