scholarly journals Positron annihilation localization by nanoscale magnetization

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yaser H. Gholami ◽  
Hushan Yuan ◽  
Moses Q. Wilks ◽  
Lee Josephson ◽  
Georges El Fakhri ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Region Of Interest ◽  
Superparamagnetic Iron Oxide ◽  
Fold Increase ◽  
Positron Range ◽  
Positron Emission ◽  
Physical Limit ◽  
Diagnostic Agents ◽  
Image Blurring ◽  
Pet Instrumentation

AbstractIn positron emission tomography (PET), the finite range over which positrons travel before annihilating with an electron places a fundamental physical limit on the spatial resolution of PET images. After annihilation, the photon pair detected by the PET instrumentation is emitted from a location that is different from the positron-emitting source, resulting in image blurring. Here, we report on the localization of positron range, and hence annihilation quanta, by strong nanoscale magnetization of superparamagnetic iron oxide nanoparticles (SPIONs) in PET-MRI. We found that positron annihilations localize within a region of interest by up to 60% more when SPIONs are present (with [Fe] = 3 mM) compared to when they are not. The resulting full width at half maximum of the PET scans showed the spatial resolution improved by up to $$\approx$$ ≈  30%. We also found evidence suggesting that the radiolabeled SPIONs produced up to a six-fold increase in ortho-positronium. These results may also have implications for emerging cancer theranostic strategies, where charged particles are used as therapeutic as well as diagnostic agents and improved dose localization within a tumor is a determinant of better treatment outcomes.

scholarly journals Imaging Salt Uptake Dynamics in Plants Using PET

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Gerard Ariño-Estrada ◽  
Gregory S. Mitchell ◽  
Prasenjit Saha ◽  
Ahmad Arzani ◽  
Simon R. Cherry ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Sodium Transport ◽  
Crop Production ◽  
Small Animal ◽  
Region Of Interest ◽  
Salt Transport ◽  
Small Animal Pet ◽  
Transport Dynamics ◽  
Positron Emission ◽  
Over Time

AbstractSoil salinity is a global environmental challenge for crop production. Understanding the uptake and transport properties of salt in plants is crucial to evaluate their potential for growth in high salinity soils and as a basis for engineering varieties with increased salt tolerance. Positron emission tomography (PET), traditionally used in medical and animal imaging applications for assessing and quantifying the dynamic bio-distribution of molecular species, has the potential to provide useful measurements of salt transport dynamics in an intact plant. Here we report on the feasibility of studying the dynamic transport of 22Na in millet using PET. Twenty-four green foxtail (Setaria viridis L. Beauv.) plants, 12 of each of two different accessions, were incubated in a growth solution containing 22Na+ ions and imaged at 5 time points over a 2-week period using a high-resolution small animal PET scanner. The reconstructed PET images showed clear evidence of sodium transport throughout the whole plant over time. Quantitative region-of-interest analysis of the PET data confirmed a strong correlation between total 22Na activity in the plants and time. Our results showed consistent salt transport dynamics within plants of the same variety and important differences between the accessions. These differences were corroborated by independent measurement of Na+ content and expression of the NHX transcript, a gene implicated in sodium transport. Our results demonstrate that PET can be used to quantitatively evaluate the transport of sodium in plants over time and, potentially, to discern differing salt-tolerance properties between plant varieties. In this paper, we also address the practical radiation safety aspects of working with 22Na in the context of plant imaging and describe a robust pipeline for handling and incubating plants. We conclude that PET is a promising and practical candidate technology to complement more traditional salt analysis methods and provide insights into systems-level salt transport mechanisms in intact plants.

Extrastriatal Dopamine D2/3 Receptor Availability in Alcohol Use Disorder and Individuals at High Risk

2022 ◽  
pp. 1-10
Author(s):  
Gianna Spitta ◽  
Tobias Gleich ◽  
Kristin Zacharias ◽  
Oisin Butler ◽  
Ralph Buchert ◽  
...  
Keyword(s):  
High Risk ◽  
Alcohol Use ◽  
Alcohol Use Disorder ◽  
Protective Factor ◽  
Region Of Interest ◽  
Anterior Cingulate ◽  
Dopamine D2 ◽  
Positron Emission ◽  
Significant Difference ◽  
Meta Analyses

<b><i>Introduction:</i></b> Reduced striatal dopamine D2/3 receptor availability in alcohol use disorder (AUD) has been demonstrated in recent clinical studies and meta-analyses. However, only a limited number of studies investigated extrastriatal D2/3 availability in AUD or in at-risk populations. In line with a dimensional understanding of addiction, extrastriatal dopaminergic neuroadaptations have been suggested to be relevant from a pathobiological perspective. <b><i>Methods:</i></b> We investigated D2/3 receptor availability via <sup>18</sup>F-fallypride positron emission tomography applying a region of interest (ROI) approach. We selected ROIs for the prefrontal cortex (PFC) and the anterior cingulate cortex (ACC). Our sample included 19 healthy controls (low risk [LR]), 19 individuals at high risk (HR) to develop addiction, and 20 recently detoxified AUD patients. <b><i>Results:</i></b> We found significantly higher D2/3 receptor availability of HR compared to AUD in the left and right rostral ACC (rACC), as well as in the left ventrolateral PFC (vlPFC). We did not observe a significant difference between AUD and LR. After corrections for multiple comparisons none of the ROIs reached significance throughout the group comparison. The D2/3 receptor availability in the left rACC was inversely correlated with symptom severity assessed with the Alcohol Dependency Scale. <b><i>Discussion:</i></b> To our knowledge, the present work is the first study investigating extrastriatal D2/3 receptor availabilities in individuals at HR and patients with AUD. The observation that D2/3 receptor availabilities are highest in HR might suggest that their pathobiology differs from subjects with AUD. Future studies are necessary to clarify the intraindividual course of this biomarker over different disease stages and its possible role as a risk or protective factor.

scholarly journals NEMA NU4-2008 Performance Evaluation of Albira: A Two-Ring Small-Animal PET System Using Continuous LYSO Crystals

2016 ◽  
Vol 3 (1) ◽  
pp. 12-26 ◽  
Author(s):  
Malgorzata Z. Pajak ◽  
David Volgyes ◽  
Sally L. Pimlott ◽  
Carlos C. Salvador ◽  
Antonio S. Asensi ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Small Animal Imaging ◽  
Small Animal ◽  
Axial Direction ◽  
Small Animal Pet ◽  
Performance Review ◽  
Good Spatial Resolution ◽  
Positron Emission ◽  
Animal Images ◽  
Pet System

Goals:This paper presents the performance review based on a dual-ring Positron Emission Tomography (PET) scanner being a part of Bruker Albira: a multi-modal small-animal imaging platform. Each ring of Albira PET contains eight detectors arranged as octagon, and each detector is built using a single continuous lutetium-yttrium oxyorthosilicate crystal and multi-anode photo multiplier tube. In two-ring configuration, the scanner covers 94.4 mm in axial- and 80´80 mm in trans-axial direction, which is sufficient to acquire images of small animals (e.g.mice) without the need of moving the animal bed during the scan.Methods:All measurements and majority of data processing were performed according to the NEMA NU4-2008 standard with one exception. Due to the scanner geometry, the spatial resolution test was reconstructed using iterative algorithm instead of the analytical one. The main performance characteristics were compared with those of the other PET sub-systems of tri-modal small-animal scanners.Results:The measured spatial resolution at the centre of the axial field of view in radial, tangential and axial directions was 1.72, 1.70 and 2.45 mm, respectively. The scatter fraction for the mouse-like phantom was 9.8% and for the rat-like phantom, 21.8%. The maximum absolute sensitivity was 5.30%. Finally, the recovery co-efficients for 5, 4, 3, 2, 1 mm diameter rods in image quality phantom were: 0.90, 0.77, 0.66, 0.30 and 0.05, respectively.Conclusion:The Bruker Albira is a versatile small-animal multi-modal device that can be used for variety of studies. Overall the PET sub-system provides a good spatial resolution coupled with better-than average sensitivity and the ability to produce good quality animal images when administering low activities.

4D flow MRI: impact of region of interest size, angulation and spatial resolution on aortic flow assessment

2021 ◽  
Vol 42 (3) ◽  
pp. 035004 ◽  
Author(s):  
M E Casciaro ◽  
A F Pascaner ◽  
F N Guilenea ◽  
J Alcibar ◽  
U Gencer ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Region Of Interest ◽  
Aortic Flow ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

scholarly journals PDMS Nano-Modified Scaffolds for Improvement of Stem Cells Proliferation and Differentiation in Microfluidic Platform

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 668 ◽  
Author(s):  
Hadi Hashemzadeh ◽  
Abdollah Allahverdi ◽  
Mosslim Sedghi ◽  
Zahra Vaezi ◽  
Tahereh Tohidi Moghadam ◽  
...  
Keyword(s):  
Stem Cells ◽  
Surface Roughness ◽  
Stem Cell ◽  
Cell Surface ◽  
Superparamagnetic Iron Oxide ◽  
Fold Increase ◽  
Stem Cell Differentiation ◽  
Gold Nanowires ◽  
Cell Substrate ◽  
Proliferation And Differentiation

Microfluidics cell-based assays require strong cell-substrate adhesion for cell viability, proliferation, and differentiation. The intrinsic properties of PDMS, a commonly used polymer in microfluidics systems, regarding cell-substrate interactions have limited its application for microfluidics cell-based assays. Various attempts by previous researchers, such as chemical modification, plasma-treatment, and protein-coating of PDMS revealed some improvements. These strategies are often reversible, time-consuming, short-lived with either cell aggregates formation, not cost-effective as well as not user- and eco-friendly too. To address these challenges, cell-surface interaction has been tuned by the modification of PDMS doped with different biocompatible nanomaterials. Gold nanowires (AuNWs), superparamagnetic iron oxide nanoparticles (SPIONs), graphene oxide sheets (GO), and graphene quantum dot (GQD) have already been coupled to PDMS as an alternative biomaterial enabling easy and straightforward integration during microfluidic fabrication. The synthesized nanoparticles were characterized by corresponding methods. Physical cues of the nanostructured substrates such as Young’s modulus, surface roughness, and nanotopology have been carried out using atomic force microscopy (AFM). Initial biocompatibility assessment of the nanocomposites using human amniotic mesenchymal stem cells (hAMSCs) showed comparable cell viabilities among all nanostructured PDMS composites. Finally, osteogenic stem cell differentiation demonstrated an improved differentiation rate inside microfluidic devices. The results revealed that the presence of nanomaterials affected a 5- to 10-fold increase in surface roughness. In addition, the results showed enhancement of cell proliferation from 30% (pristine PDMS) to 85% (nano-modified scaffolds containing AuNWs and SPIONs), calcification from 60% (pristine PDMS) to 95% (PDMS/AuNWs), and cell surface marker expression from 40% in PDMS to 77% in SPION- and AuNWs-PDMS scaffolds at 14 day. Our results suggest that nanostructured composites have a very high potential for stem cell studies and future therapies.

scholarly journals Use of Superparamagnetic Iron Oxide Nanoparticles (SPIONs) via Multiple Imaging Modalities and Modifications to Reduce Cytotoxicity: An Educational Review

2020 ◽  
Vol 1 (1) ◽  
pp. 105-135
Author(s):  
Nicholas Nelson ◽  
John Port ◽  
Mukesh Pandey
Keyword(s):  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Targeted Delivery ◽  
Superparamagnetic Iron Oxide ◽  
Superparamagnetic Iron Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Positron Emission ◽  
Multiple Imaging ◽  
Specific Accumulation ◽  
Magnetic Resonance Imaging Mri

The aim of the present educational review on superparamagnetic iron oxide nanoparticles (SPIONs) is to inform and guide young scientists and students about the potential use and challenges associated with SPIONs. The present review discusses the basic concepts of magnetic resonance imaging (MRI), basic construct of SPIONs, cytotoxic challenges associated with SPIONs, shape and sizes of SPIONs, site-specific accumulation of SPIONs, various methodologies applied to reduce cytotoxicity including coatings with various materials, and application of SPIONs in targeted delivery of chemotherapeutics (Doxorubicin), biotherapeutics (DNA, siRNA), and positron emission tomography (PET) imaging applications.

scholarly journals 11C-Diprenorphine Binding in Huntington's Disease: A Comparison of Region of Interest Analysis with Statistical Parametric Mapping

1997 ◽  
Vol 17 (9) ◽  
pp. 943-949 ◽  
Author(s):  
Robert A. Weeks ◽  
Vincent J. Cunningham ◽  
Paola Piccini ◽  
Simon Waters ◽  
Anita E. Harding ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Statistical Parametric Mapping ◽  
Region Of Interest ◽  
Emission Tomography ◽  
Z Score ◽  
Parametric Images ◽  
Positron Emission ◽  
Opioid Binding ◽  
Static Images ◽  
Analytical Approaches

We compare region of interest (ROI) analytical approaches with statistical parametric mapping (SPM) of 11C-diprenorphine positron emission tomography findings in five patients with Huntington's disease (HD) and nine age-matched controls. The ROI were placed on caudate, putamen, and an occipital reference area. Ratios of striatal–occipital uptake from averaged static images centered at 60 minutes showed a mean 20% reduction in caudate ( P = 0.034) and 15% reduction in putamen ( P = 0.095) receptor binding in the HD patients. Dynamic data from caudate and putamen ROI, together with a plasma tracer input function, were analyzed using spectral analysis to give regional impulse response functions. Regional data at 60 minutes after impulse showed a mean 29% decrease in caudate ( P = 0.006) and 23% decrease in putamen ( P = 0.029) opioid binding in the HD cohort. Parametric images of tracer binding also were produced with spectral analysis on a voxel basis. The images of the unit impulse response function at 60 minutes showed a mean 31 % decrease in caudate ( P = 0.005) and a 26% decrease in putamen binding ( P = 0.011) in HD. The voxel-based parametric images were transformed into standard stereotactic space, and a between-group comparison (patient versus controls) was performed with SPM. This approach revealed symmetrical decreases in caudate (peak 40% decrease, z score = 4.38) and putamen opioid binding (peak 24% decrease, z score = 4.686) with additional nonhypothesized changes in cingulate, prefrontal, and thalamic areas. The significance and precision of changes measured with spectral analysis applied to dynamic data sets were superior to ROI-based ratio analysis on static images. The SPM replicated the striatal reductions in opioid binding in HD and detected additional nonpredicted changes. This study suggests that SPM is a valid alternative to conventional ROI analytical approaches for determining binding changes with positron emission tomography and may have advantages over region-based analyses in exploratory studies.

Zinc Superparamagnetic Iron Oxide Nanoparticles for Use as MRI Contrast Agents

2007 ◽  
Author(s):  
Carlos Bárcena ◽  
Chalermchai Khemtong ◽  
Girija S. Chaubey ◽  
Chase W. Kessinger ◽  
J. Ping Liu ◽  
...  
Keyword(s):  
Single Photon ◽  
Photon Emission ◽  
Superparamagnetic Iron Oxide ◽  
Mri Contrast Agents ◽  
Emission Computed Tomography ◽  
Specific Information ◽  
Mri Contrast ◽  
Early Detection Of Disease ◽  
Positron Emission ◽  
Magnetic Resonance Imaging Mri

Molecular imaging has become a rapidly evolving field used in various applications to target macromolecules and biological process [1,2]. Various imaging systems, such as single photon emission computed tomography (SPECT), positron emission tomography (PET), computerized tomography (CT), and magnetic resonance imaging (MRI), use non-invasive techniques that provide disease-specific information through diagnostic imaging. Early detection of disease demonstrates the potential benefit of these systems.

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