PET-BIDS, an extension to the brain imaging data structure for positron emission tomography

The Brain Imaging Data Structure (BIDS) is a standard for organizing and describing neuroimaging datasets, serving not only to facilitate the process of data sharing and aggregation, but also to simplify the application and development of new methods and software for working with neuroimaging data. Here, we present an extension of BIDS to include positron emission tomography (PET) data, also known as PET-BIDS, and share several open-access datasets curated following PET-BIDS along with tools for conversion, validation and analysis of PET-BIDS datasets

PET-BIDS, an extension to the brain imaging data structure for positron emission tomography

The Brain Imaging Data Structure (BIDS) is a standard for organizing and describing neuroimaging datasets. It serves not only to facilitate the process of data sharing and aggregation, but also to simplify the application and development of new methods and software for working with neuroimaging data. Here, we present an extension of BIDS to include positron emission tomography (PET) data (PET-BIDS). We describe the PET-BIDS standard in detail and share several open-access datasets curated following PET-BIDS. Additionally, we highlight several tools which are already available for converting, validating and analyzing PET-BIDS datasets.Competing Interest StatementThe authors have declared no competing interest

Mapping neurotransmitter systems to the structural and functional organization of the human neocortex

Neurotransmitter receptors support the propagation of signals in the human brain. How receptor systems are situated within macro-scale neuroanatomy and how they shape emergent function remain poorly understood, and there exists no comprehensive atlas of receptors. Here we collate positron emission tomography data from more than 1,200 healthy individuals to construct a whole-brain three-dimensional normative atlas of 19 receptors and transporters across nine different neurotransmitter systems. We found that receptor profiles align with structural connectivity and mediate function, including neurophysiological oscillatory dynamics and resting-state hemodynamic functional connectivity. Using the Neurosynth cognitive atlas, we uncovered a topographic gradient of overlapping receptor distributions that separates extrinsic and intrinsic psychological processes. Finally, we found both expected and novel associations between receptor distributions and cortical abnormality patterns across 13 disorders. We replicated all findings in an independently collected autoradiography dataset. This work demonstrates how chemoarchitecture shapes brain structure and function, providing a new direction for studying multi-scale brain organization.</p

Investigation of Atomoxetine Occupancy of Serotonin Transporters

Objectives: Atomoxetine (ATX) is a putative selective norepinephrine transporter (NET) reuptake inhibitor and is used for treatment of depression and attention-deficit/hyperactivity disorder. We have shown that ATX displayed a dose-dependent occupancy on NET using PET and [11C]MRB, a selective NET radioligand [1]. Our previous study also indicated that ATX (1.5 mg/kg) blocked the binding of the SERT ligand [11C]DASB in the baboon brain, an effect similar to that of fluoxetine (an SSRI) [2]. The purpose of this study was to determine if ATX, at clinically relevant doses, occupied SERT in a dose-dependent fashion in rhesus monkeys, using PET and [11C]AFM, a highly selective radioligand for SERT [3].\nMethods: Following a similar scanning paradigm as our previous study using [11C]MRB [1], rhesus monkeys were scanned four times with [11C]AFM (baseline & medium dose of ATX on day 1; low & high doses of ATX on day 2). ATX or saline infusion began 2 h before each scan, lasting until the end of the 2 h scan, to mimic the human oral dose PK profile. Infusion rates ranged 0.045-1.054 mg/kg/h. ATX plasma levels and arterial input functions were measured. Distribution volumes (VT) were estimated by one-tissue compartment model and ATX IC50 values were calculated.\nResults: In baseline scans, regional brain [11C]AFM VT [mL/cm3] reflected the known distribution of SERT, with high binding in the brainstem (VT = 127+-52) and thalamus (VT = 114+-23), intermediate binding in temporal cortex (VT = 73+-13), and lowest binding in the cerebellum (VT = 36+-0.6). VT in the cerebellum was reduced by up to 32% with increasing ATX dose, suggesting that there was some contribution of specific binding to the cerebellum signal. Receptor occupancy (r) and non displaceable volume of distribution (VND) were calculated from the occupancy model in the absence of an ideal reference region [4]: VT(baseline) - VT(post-drug) = r * (VT(baseline) - VND). After administration of ATX, a dose-dependent occupancy from 49 to 90% was observed. The IC50 was estimated to be 167+-16 ng/mL of plasma ATX concentration (corresponding to an infusion rate of 0.126+-0.013 mg/kg/h). At a therapeutic ATX dose (1.8 mg/kg, ~600 ng/mL plasma) ATX would have occupied ~80% of SERT.\nConclusions: This study demonstrated that ATX inhibited [11C]AFM binding in rhesus monkey brain in a dose-dependent fashion. Compared with our reported ATX IC50 value for NET with [11C]MRB [3], the ATX in vivo IC50 ratio of SERT to NET was ~6, consistent with the reported in vitro affinity (Kd) ratio of ~4.5 (8.9 and 2 nM for SERT and NET, respectively) [5]. Our comparative studies of ATX effects on NET and SERT suggest that ATX at clinical doses occupies both transporters. Thus, PET occupancy studies are important in clarifying the mechanism of ATX therapeutic action.\nReferences:[1] Gallezot J-D, et al., NeuroImage, 41:T49, 2008.[2] Ding Y-S and Fowler, J, NMB, 32:707-718, 2005.[3] Huang Y, et al., NMB, 31:543-556, 2004.[4] Lassen NA, et al., JCBFM, 15: 152-165, 1995.[5] Tatsumi M, et. al., EJP, 340: 249-258, 1997.Brain\u2709 & BrainPET\u270

Partial volume correction analysis for 11C-UCB-J PET studies of Alzheimer's disease

Purpose: 11C-UCB-J PET imaging, targeting synaptic vesicle glycoprotein 2A (SV2A), has been shown to be a useful indicator of synaptic density in Alzheimer's disease (AD). For SV2A imaging, a decrease in apparent tracer uptake is often due to the combination of gray-matter (GM) atrophy and SV2A decrease in the remaining tissue. Our aim is to reveal the true SV2A change by performing partial volume correction (PVC). Methods: We performed two PVC algorithms, Müller-Gärtner (MG) and ‘iterative Yang’ (IY), on 17 AD participants and 11 cognitive normal (CN) participants using the brain-dedicated HRRT scanner. Distribution volume VT, the rate constant K1, binding potential BPND (centrum semiovale as reference region), and tissue volume were compared. Results: In most regions, both PVC algorithms reduced the between-group differences. Alternatively, in hippocampus, IY increased the significance of between-group differences while MG reduced it (VT, BPND and K1 group differences: uncorrected: 20%, 27%, 17%; MG: 18%, 22%, 14%; IY: 22%, 28%, 17%). The group difference in hippocampal volume (10%) was substantially smaller than any PET measures. MG increased GM binding values to a greater extent than IY due to differences in algorithm assumptions. Conclusion: 11C-UCB-J binding is significantly reduced in AD hippocampus, but PVC is important to adjust for significant volume reduction. After correction, PET measures are substantially more sensitive to group differences than volumetric MRI measures. Assumptions of each PVC algorithm are important and should be carefully examined and validated. For 11C-UCB-J, the less stringent assumptions of IY support its use as a PVC algorithm over MG

Forum DocNum - présentation des textes et commentaires

Forum DocNum - présentation des textes et commentaires d'une liste de discussion autour du document numérique. Marc Augier, Evelyne Broudoux, Dominique Cotte, Olivier Ertzscheid, Gabriel Gallezot, Yves Jeanneret, Sylvie Merviel, Niels Windfeld Lund, Jean-Discussion autour de la définition du "document numérique"Discussion about definition of "digital document