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[IEEE 2019 16th International Conference on the European Energy Market (EEM) - Ljubljana, Slovenia (2019.9.18-2019.9.20)] 2019 16th International Conference on the European Energy Market (EEM) - Shapley-Value-Based Distribution of the Costs of Solar Photovoltaic Plant Grid Connection
摘要： Positron emission tomography (PET) images are typically reconstructed with an in-plane pixel size of approximately 4 mm for cancer imaging. The objective of this work was to evaluate the effect of using smaller pixels on general oncologic lesion-detection. A series of observer studies was performed using experimental phantom data from the Utah PET Lesion Detection Database, which modeled whole-body FDG PET cancer imaging of a 92 kg patient. The data comprised 24 scans over 4 days on a Biograph mCT time-of-flight (TOF) PET/CT scanner, with up to 23 lesions (diam. 6–16 mm) distributed throughout the phantom each day. Images were reconstructed with 2.036 mm and 4.073 mm pixels using ordered-subsets expectation-maximization (OSEM) both with and without point spread function (PSF) modeling and TOF. Detection performance was assessed using the channelized non-prewhitened numerical observer with localization receiver operating characteristic (LROC) analysis. Tumor localization performance and the area under the LROC curve were then analyzed as functions of the pixel size. In all cases, the images with ～2 mm pixels provided higher detection performance than those with ～4 mm pixels. The degree of improvement from the smaller pixels was larger than that offered by PSF modeling for these data, and provided roughly half the benefit of using TOF. Key results were confirmed by two human observers, who read subsets of the test data. This study suggests that a significant improvement in tumor detection performance for PET can be attained by using smaller voxel sizes than commonly used at many centers. The primary drawback is a 4-fold increase in reconstruction time and data storage requirements.
关键词： PET/CT reconstruction,PET/CT,image reconstruction,Image quality assessment
更新于2025-09-16 10:30:52
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[IEEE 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Sydney, Australia (2018.11.10-2018.11.17)] 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC) - PET-enabled Dual-energy CT: A Proof-of-Concept Simulation Study
摘要： Standard dual-energy CT uses two different x-ray energies to obtain energy-dependent tissue attenuation information to allow quantitative material decomposition. Combined use of dual-energy CT and PET may provide a more comprehensive characterization of disease states in cancer and many other integration of dual-energy CT with PET diseases. However, is not trivial, either requiring costly hardware upgrade or increasing radiation dose. This paper proposes a novel dual-energy CT imaging method that is enabled by the already-available PET data on PET/CT. Instead of using a second x-ray CT scan with a different energy, this method exploits time-of-flight PET image reconstruction to obtain a 511 keV gamma-ray attenuation image from PET emission data and combines the high-energy gamma-ray CT image with the low-energy x-ray CT of PET/CT to provide a pair of dual-energy CT images. We conducted a computer simulation to test the concept for material decomposition using air, soft tissue, fat and calcium. The simulations results indicate that this PET-enabled dual-energy CT method is promising for quantitative material decomposition, though future work is needed for noise supression. The proposed method can be readily implemented on time-of-flight PET/CT scanners to enable simultaneous PET and dual-energy CT for multiparametric imaging.
关键词： Time-of-flight PET,multi-material decomposition,image reconstruction,dual-energy CT
更新于2025-09-16 10:30:52
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UV LED Curing of Hydrogel-Modified Textiles with High Anti-Fouling Resistance
摘要： The hydrogel grafted polyethylene terephthalate (PET) textiles were envisioned to have oil-repelling properties due to the synergistic of combining hydrophilic hydrogel onto PET textiles surfaces. In this work, PAAm hydrogels were grafted i.e. via immersion or dipping methods onto pristine (PPET) and alkaline treated (APET) PET textile surfaces using UV LED light source. The obtained samples were then characterized based on the degree of grafting (DG), Fourier transformed infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), surface wettability by contact angle and oil fouling test. APET was found to be more efficient for grafting compared to the PPET due to the surface modification made after the alkaline treatment. APET surface turned to be more hydrophilic than PPET due to the presence of hydroxyl group (-OH) as proven in the FTIR. In addition, the PAAm hydrogel was confirmed to be successfully grafted onto the APET textile via immersion or dipping methods with the optimum DG obtained was at 20 minutes of UV time. This finding has also proven the potential of UV LED as a promising technology to replace the conventional UVA for hydrogel curing. Higher DG was obtained for immersed grafting sample (PAAm-g-APETimm; DG=160 wt%) when compared to the dipped sample (PAAm-g-APETdip; DG=60 wt%) which indicates that higher mass fraction of PAAm could be attached to the surface of PAAm-g-APETimm. Apart from that, PAAm-g-APETimm shows lower water contact angle (WCA) with WCA=60.90° as compared to PAAm-g-APETdip with WCA=83.15° which could be due to higher thickness of hydrophilic layer that resulted in slower rate of oil fouling performance. To summarize, the PAAm hydrogel grafted onto PET textiles were significantly improved and possessed excellent surface towards oil staining performance. By comparing both textile modifications, grafting via dipping was more preferable. Even though the DG obtained was slightly lower, its thin layer of hydrogel grafted on the APET textile surface was sufficient to de-stain oil from the textile surface at a faster rate (~0.60-0.70 seconds). To some extent; the hydrogel modified textiles via UV LED curing has bright vision in the near future as promising tools for oil/water separation.
关键词： UV LED,PAAm hydrogel,Anti oil-fouling resistance,Photografting,PET textiles
更新于2025-09-16 10:30:52
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In vivo comparison of N-11CH3 vs O-11CH3 radiolabeled microtubule targeted PET ligands
摘要： Altered dynamics of microtubules (MT) are implicated in the pathophysiology of a number of brain diseases. Therefore, radiolabeled MT targeted ligands that can penetrate the blood brain barrier (BBB) may offer a direct and sensitive approach for diagnosis, and assessing the clinical potential of MT targeted therapeutics using PET imaging. We recently reported two BBB penetrating radioligands, [11C]MPC-6827 and [11C]HD-800 as specific PET ligands for imaging MTs in brain. The major metabolic pathway of the above molecules is anticipated to be via the initial labeling site, O-methyl, compared to the N-methyl group. Herein, we report the radiosynthesis of N-11CH3-MPC-6827 and N-11CH3-HD-800 and a comparison of their in vivo binding with the corresponding O-11CH3 analogues using microPET imaging and biodistribution methods. Both O-11CH3 and N-11CH3 labeled MT tracers exhibit high specific binding and brain. The N-11CH3 labeled PET ligands demonstrated similar in vivo binding characteristics compared with the corresponding O-11CH3 labeled tracers, [11C]MPC-6827 and [11C]HD-800 respectively.
关键词： brain,PET,microtubule,tubulin,radiotracer
更新于2025-09-16 10:30:52
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Radiology, Lasers, Nanoparticles and Prosthetics || 7. Positron emission tomography
摘要： Positron emission tomography (PET) is a nuclear imaging modality used in clinics for cardiologic, neurologic, and oncologic studies. The PET method is based on the annihilation of positrons and electrons via converting their rest mass into two γ-photons flying in opposite directions. These two γ-photons are detected in a fashion similar to SPE or SPECT. Positron annihilation spectroscopy (PAS) is also used in condensed matter physics for determining the density and diffusivity of defects in solids. PAS is the opposite effect to pair production, which occurs when photons interact with nuclei at photon energies beyond 1 MeV. Pair production is important for cancer treatment with very hard x-rays, discussed in Chapter 9. However in this chapter we consider PET as an analytic tool.
关键词： nuclear imaging,PET,positron annihilation spectroscopy,γ-photons,Positron emission tomography,PAS
更新于2025-09-16 10:30:52
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Oxygen Tolerant PET-RAFT Facilitated 3D Printing of Polymeric Materials under Visible LEDs
摘要： Photopolymerization-based 3D printing process is typically conducted using free radical polymerization, which leads to fabrication of immutable materials. An alternative 3D printing of polymeric materials using trithiocarbonate (TTC) reversible addition-fragmentation chain transfer (RAFT) agents has always been a challenge for material and polymer scientists. Herein we report 3D printing of RAFT-based formulations that can be conducted fully open to air using standard digital light processing (DLP) 3D printer and under mild conditions of visible light at blue (λ max = 483 nm, 4.16 mW/cm2) or green (λ max = 532 nm, 0.48 mW/cm2) wavelength. Our approach is based on activation of TTC RAFT agents using eosin Y (EY) as a photoinduced electron-transfer (PET) catalyst in the presence of a reducing agent (triethylamine (TEA)), which facilitated oxygen tolerant 3D printing process via a reductive PET initiation mechanism. Re-activation of the TTCs present within the polymer networks enables post-printing monomer insertion into the outer layers of an already printed dormant object under a second RAFT process, which provides a pathway to design a more complex 3D printing. To our best knowledge, this is the first example of oxygen tolerant EY/TEA catalyzed PET-RAFT facilitated 3D printing of polymeric materials. We believe that our strategy is a significant step forward in the field of 3D printing.
关键词： Oxygen Tolerant,Trithiocarbonate,3D Printing,Visible Light-Induced PET-RAFT Polymerization,Digital Light Processing,Photoinduced Electron-Transfer
更新于2025-09-16 10:30:52
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Hybrid Imaging of Aspergillus fumigatus Pulmonary Infection with Fluorescent, 68Ga-Labelled Siderophores
摘要： Aspergillus fumigatus (A. fumigatus) is a human pathogen causing severe invasive fungal infections, lacking sensitive and selective diagnostic tools. A. fumigatus secretes the siderophore desferri‐triacetylfusarinine C (TAFC) to acquire iron from the human host. TAFC can be labelled with gallium‐68 to perform positron emission tomography (PET/CT) scans. Here, we aimed to chemically modify TAFC with fluorescent dyes to combine PET/CT with optical imaging for hybrid imaging applications. Starting from ferric diacetylfusarinine C ([Fe]DAFC), different fluorescent dyes were conjugated (Cy5, SulfoCy5, SulfoCy7, IRDye 800CW, ATTO700) and labelled with gallium‐68 for in vitro and in vivo characterisation. Uptake assays, growth assays and live‐cell imaging as well as biodistribution, PET/CT and ex vivo optical imaging in an infection model was performed. Novel fluorophore conjugates were recognized by the fungal TAFC transporter MirB and could be utilized as iron source. Fluorescence microscopy showed partial accumulation into hyphae. μPET/CT scans of an invasive pulmonary aspergillosis (IPA) rat model revealed diverse biodistribution patterns for each fluorophore. [68Ga]Ga‐DAFC‐Cy5/SufloCy7 and ‐IRDye 800CW lead to a visualization of the infected region of the lung. Optical imaging of ex vivo lungs corresponded to PET images with high contrast of infection versus non‐infected areas. Although fluorophores had a decisive influence on targeting and pharmacokinetics, these siderophores have potential as a hybrid imaging compounds combining PET/CT with optical imaging applications.
关键词： fluorescence microscopy,PET,near infrared,siderophores,gallium‐68,invasive pulmonary aspergillosis
更新于2025-09-16 10:30:52
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Synthesis and evaluation of zirconium-89 labelled and long-lived GLP-1 receptor agonists for PET imaging
摘要： Introduction: Lately, zirconium-89 has shown great promise as a radionuclide for PET applications of long circulating biomolecules. Here, the design and synthesis of protracted and long-lived GLP-1 receptor agonists conjugated to desferrioxamine and labelled with zirconium-89 is presented with the purpose of studying their in vivo distribution by PET imaging. The labelled conjugates were evaluated and compared to a non-labelled GLP-1 receptor agonist in both in vitro and in vivo assays to certify that the modification did not significantly alter the peptides’ structure or function. Finally, the zirconium-89 labelled peptides were employed in PET imaging, providing visual verification of their in vivo biodistribution. Methods: The evaluation of the radiolabelled peptides and comparison to their non-labelled parent peptide was performed by in vitro assays measuring binding and agonistic potency to the GLP-1 receptor, physicochemical studies aiming at elucidating change in peptide structure upon bioconjugation and labelling as well as an in vivo food in-take study illustrating the compounds’ pharmacodynamic properties. The biodistribution of the labelled GLP-1 analogues was determined by ex vivo biodistribution and in vivo PET imaging. Results: The results indicate that it is surprisingly feasible to design and synthesize a protracted, zirconium-89 labelled GLP-1 receptor agonist without losing in vitro potency or affinity as compared to a non-labelled parent peptide. Physicochemical properties as well as pharmacodynamic properties are also maintained. The biodistribution in rats show high accumulation of radiolabelled peptide in well-perfused organs such as the liver, kidney, heart and lungs. The PET imaging study confirmed the findings from the biodistribution study with a significant high uptake in kidneys and presence of activity in liver, heart and larger blood vessels. Conclusions and Advances in Knowledge: This initial study indicates the potential to monitor the in vivo distribution of long-circulating incretin hormones using zirconium-89 based PET.
关键词： GLP-1,Bioconjugation,PET,Molecular imaging,Zirconium-89,Radiolabelling
更新于2025-09-12 10:27:22
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Diagnostic value of radiolabeled amino acid PET for detection of pseudoprogression of brain tumor after treatment
摘要： The purpose of the current study was to investigate the diagnostic performance of radiolabeled amino acid PET for detection of pseudoprogression (PsP) of brain tumor after treatment through a systematic review and meta-analysis. Methods: The PubMed and EMBASE database, from the earliest available date of indexing through 15 February 2019, were searched for studies evaluating the diagnostic performance of radiolabeled amino acid PET for detection of PsP. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios, and constructed summary receiver operating characteristic (SROC) curves. Results: Across seven results from six studies (971 patients), the pooled sensitivity was 0.89 [95% confidence interval (CI): 0.82–0.94] without heterogeneity (I2 = 0.0) and a pooled specificity of 0.88 (95% CI: 0.76–0.94) without heterogeneity (I2=29.4). Likelihood ratio syntheses gave an overall positive likelihood ratio of 7.3 (95% CI: 3.6–14.7) and negative likelihood ratio of 0.12 (95% CI: 0.07–0.21). The pooled diagnostic odds ratio (DOR) was 60 (95% CI: 23–152). Hierarchical SROC curve indicates that the areas under the curve (AUC) was 0.92 (95% CI: 0.90–0.94). Conclusion: The current meta-analysis showed the good sensitivity and specificity of radiolabeled amino acid PET for detection of PsP of brain tumor after treatment. Also, the DOR was high and SROC curve showed high AUC value.
关键词： PET,diagnosis,amino acid,Pseudoprogression,brain tumor
更新于2025-09-12 10:27:22
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Semiconductor Quantum Dots Are Efficient and Recyclable Photocatalysts for Aqueous PET-RAFT Polymerization
摘要： This Letter describes the use of CdSe quantum dots (QDs) as photocatalysts for photoinduced electron transfer reversible addition?fragmentation chain transfer (PET-RAFT) polymerization of a series of aqueous acrylamides and acrylates. The high colloidal solubility and photostability of these QDs allowed polymerization to occur with high efficiency (>90% conversion in 2.5 h), low dispersity (PDI < 1.1), and ultralow catalyst loading (<0.5 ppm). The use of protein concentrators enabled the removal of the photocatalyst from the polymer and monomer with tolerable metal contamination (8.41 ug/g). These isolated QDs could be recycled for four separate polymerizations without a significant decrease in efficiency. By changing the pore size of the protein concentrators, the QDs and polymer could be separated from the remaining monomer, allowing for the synthesis of block copolymers using a single batch of QDs with minimal purification steps and demonstrating the fidelity of chain ends.
关键词： block copolymers,CdSe quantum dots,photocatalysts,aqueous acrylamides,acrylates,protein concentrators,PET-RAFT polymerization
更新于2025-09-12 10:27:22