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P1217Zirconium-89 labelled probe for molecular imaging of inflammation in experimental atherosclerosis
摘要： Early detection of in?amed atherosclerotic lesions by molecular imaging might improve risk assessment beyond that of vascular stenosis and plaque morphology imaging, and improve the clinical management of high-risk patients. To target the key features of unstable atherosclerotic lesions, we studied the feasibility of our radiotracer, based on modi?ed human serum albumin (HSA), to identify in?amed atherosclerotic lesions by in vivo molecular imaging. We applied a maleylated HSA (Mal-HSA) probe, recognised by scavenger receptors on macrophages, in an experimental imaging study of atherosclerosis. Mal-HSA was coupled with a positron-emitting metal ion, Zirconium-89 (89Zr). The targeting potential of this probe was evaluated and compared with unspeci?c 89Zr-HSA and 18F-FDG in a mouse model of atherosclerosis (Apoe?/?, n=22) and compared with wild-type (WT) mice (C57BL/6, n=21) as controls. Radiotracer accumulation in the aortic arch was analysed in vivo by the fusion of positron emission tomography–magnetic resonance imaging (PET-MRI), radiotracer bio-distribution was measured ex vivo by gamma counter, and plaque uptake was evaluated by phosphor imaging (PI) autoradiography (ARG). PET-MRI, gamma counter measurements, and PI-ARG showed the accumulation of 89Zr-Mal-HSA in the atherosclerotic lesions of Apoe?/? mice. The maximum standardised uptake value (SUVmax) for 89Zr-Mal-HSA at 16 and 20 weeks were 26% and 20% higher (P<0.05) in Apoe?/? mice than control WT mice, whereas no difference in SUVmax was found for 18F-FDG in the same animals. 89Zr-Mal-HSA uptake in the aorta as evaluated by gamma counter 48 h post-injection was 32% higher (P<0.01) for Apoe?/? mice compared to WT mice, and the aorta-to-blood ratio was 10-fold higher (P<0.001) for 89Zr-Mal-HSA compared with unspeci?c 89Zr-HSA. HSA probes were mainly distributed to the liver, spleen, kidneys, bone and lymph nodes. The PI-ARG results corroborated the PET and gamma counter measurements, showing higher accumulation of 89Zr-Mal-HSA in the aortas of Apoe?/? mice compared to WT mice; 9.4±1.4 vs 0.8±0.3% (P<0.001). The modi?ed HSA-based radiotracer showed in vivo targeting of in?amed atherosclerotic lesions of mouse aorta, which could also be veri?ed ex vivo. 89Zr-Mal-HSA seems to be a promising diagnostic tool for the identi?cation of vascular in?ammation. Further methodological studies are needed to verify its applicability for detecting rupture-prone plaques.
关键词： atherosclerosis,inflammation,Zirconium-89,PET-MRI,molecular imaging,Nuclear cardiology
更新于2025-09-23 15:19:57
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Xanthene Dye-Functionalized Conjugated Porous Polymers as Robust and Reusable Photocatalysts for Controlled Radical Polymerization
摘要： Photoinduced electron/energy transfer?reversible addition?fragmentation chain transfer (PET?RAFT) polymerization represents a versatile and highly e?cient method for polymerizations of wide-ranging monomer variances upon solar energy harvesting. Although signi?cant progress has been achieved, several drawbacks are still associated with existing photocatalysts, such as toxicity of transition metals, high cost, poor stability, and unavoidable puri?cation procedures because of the photobleaching e?ect, to name a few. Herein, 1,4-diethynylbenzene-linked xanthene dye-conjugated porous polymers (CPPs) have been established as potential heterogenous photocatalysts of PET?RAFT polymerization. With this two-dimensional planar architecture, we demonstrate dual-stimuli toggling of RAFT polymerization using two di?erent external physical manipulations: light “ON”/“OFF” and solution pH “LOW”/“HIGH”. In addition, these CPPs endowed radical polymerizations with various impressive features such as compatibility of diverse monomer formulations, unique oxygen tolerance, and ppm-level catalyst dosage. Demonstrations of chain extension and catalyst recycling further highlight the robustness and performance of this CPP catalyst. Through the study of structure?property relationship using the experimental analyses, we envisage that a series of xanthene dye-functionalized CPPs can be developed as visible light-absorbing organocatalysts rivaling transition-metal photocatalysts.
关键词： PET?RAFT polymerization,visible light-absorbing organocatalysts,xanthene dye-functionalized conjugated porous polymers,dual-stimuli toggling,heterogeneous photocatalysts
更新于2025-09-23 15:19:57
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68Ga CdTe/CdS fluorescent quantum dots for detection of tumors: investigation on the effect of nanoparticle size on stability and in vivo pharmacokinetics
摘要： Background: Quantum dots (QDs)-based theranostics offer exciting new approaches to diagnose and therapy of cancer. To take advantage of the unique properties of these fluorescent QDs for different biomedical applications, their structures, size and/or surface chemistry need to be optimized, allowing their stability and functionalities to be tailored for different biomedical applications. Methodology: Cadmium telluride/Cadmium sulfide QDs (CdTe/CdS QDs) were synthesized and their structure, size, photostability and functionalities as a bioprobe for detection of Fibrosarcoma tumors were studied and compared with Cadmium telluride (CdTe) QDs. Hence, CdTe/CdS QDs were labeled with 68Ga radionuclide for fast in vivo biological nuclear imaging. Using gamma paper chromatography (γ-PC), the physicochemical properties of the prepared labeled QDs were assessed. In vivo biodistribution and positron emission tomography (PET) imaging of the 68Ga@ CdTe/CdS QDs nanocrystals were investigated in Sprague Dawley? rats bearing Fibrosarcoma tumor. Results: CdS shell on the surface of CdTe core increases the size and photostability against high energy radiations; therefore, CdTe/CdS QDs show prolonged fluorescence as compared to CdTe QDs. Conclusion: Excellent accumulation in tumor was observed for core/shell quantum dots, but this study showed that small changes in the size of the QDs (+1 nm), after adding the CdS shell around CdTe core, greatly change their biodistribution (especially the liver uptake).
关键词： core/shell quantum dots,PET,tumor imaging,68Ga,Cadmium telluride/Cadmium sulfide
更新于2025-09-23 15:19:57
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Combining multimodal imaging and treatment features improves machine learning-based prognostic assessment in patients with glioblastoma multiforme
摘要： Background: For Glioblastoma (GBM), various prognostic nomograms have been proposed. This study aims to evaluate machine learning models to predict patients’ overall survival (OS) and progression‐free survival (PFS) on the basis of clinical, pathological, semantic MRI‐based, and FET‐PET/CT‐derived information. Finally, the value of adding treatment features was evaluated. Methods: One hundred and eighty‐nine patients were retrospectively analyzed. We assessed clinical, pathological, and treatment information. The VASARI set of semantic imaging features was determined on MRIs. Metabolic information was retained from preoperative FET‐PET/CT images. We generated multiple random survival forest prediction models on a patient training set and performed internal validation. Single feature class models were created including "clinical," "pathological," "MRI‐based," and "FET‐PET/CT‐based" models, as well as combinations. Treatment features were combined with all other features. Results: Of all single feature class models, the MRI‐based model had the highest prediction performance on the validation set for OS (C‐index: 0.61 [95% confidence interval: 0.51‐0.72]) and PFS (C‐index: 0.61 [0.50‐0.72]). The combination of all features did increase performance above all single feature class models up to C‐indices of 0.70 (0.59‐0.84) and 0.68 (0.57‐0.78) for OS and PFS, respectively. Adding treatment information further increased prognostic performance up to C‐indices of 0.73 (0.62‐0.84) and 0.71 (0.60‐0.81) on the validation set for OS and PFS, respectively, allowing significant stratification of patient groups for OS. Conclusions: MRI‐based features were the most relevant feature class for prognostic assessment. Combining clinical, pathological, and imaging information increased predictive power for OS and PFS. A further increase was achieved by adding treatment features.
关键词： prognostic model,machine learning,VASARI,glioblastoma,FET‐PET,biomarker,MRI
更新于2025-09-23 15:19:57
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Achieving reliable coincidence resolving time measurement of PET detectors using multichannel waveform digitizer based on DRS4 chip
摘要： Coincidence resolving time (CRT) is one of the most important physical-performance measures for positron emission tomography (PET), as reconstruction with accurate time-of-flight information enhances the lesion detectability in patient studies. Accordingly, various PET detector designs and high-performance front-end readout circuits have been actively investigated to improve timing performance. The resulting PET detectors are often evaluated using multichannel waveform digitizers for versatile data analysis of the output signals. However, we have found that inappropriate data acquisition (DAQ) using a multichannel waveform digitizer based on the domino-ring-sampler 4 (DRS4) chip can lead to a considerable error when determining CRT. To address this issue, we performed CRT measurements using a pair of Hamamatsu R9800 photomultiplier tube based PET detectors. Then, considering intra- and inter-chip sampling, we employed four different combinations of input channels into the CAEN DT5742B waveform digitizer and obtained 2D CRT maps according to the leading-edge discriminator threshold for assessing each DAQ scheme. The intra-chip CRT measurement exhibited unusual streak patterns in the 2D CRT map and yielded the artificially-low CRT information in PET detector pairs, whereas the inter-chip CRT measurement provided the reliable estimation of timing resolution. Further, we could prevent the high-frequency signal crosstalk among input channels within the DRS4 chip using the inter-chip CRT measurement. We expect that our findings will also be useful for achieving the reliable CRT measurements when using other single-chip-based multichannel waveform digitizers.
关键词： coincidence resolving time (CRT),multichannel waveform digitizer,position emission tomography (PET),DRS4 chip,timing resolution
更新于2025-09-23 15:19:57
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Dual layer doI detector modules for a dedicated mouse brain PET/MRI
摘要： This work discusses two system geometries including their associated block detectors. Both configurations were based on a dual layer offset structure with small crystals sizes, in the order of 1×1×4/6 mm3, to provide discrete depth of interaction information. The detector for configuration “A” was based on a 4×4 silicon photomultiplier (SiPM) array attached to an optical diffusor, and a 12×12 as well as a 9×11 LSO crystal array, to achieve optimal system sensitivity. This configuration was evaluated by a double layer of 12×12 crystals. Configuration “B” was composed of three 2×2 SiPM arrays equipped with a 1 mm diffusor to read out an LSO stack of 20×6 and 19×5 individual crystals. The average peak-to-valley ratio of the inner/outer layer was 3.5/3.6 for detector “A”, and 3.4/2.8 for detector “B”. The average full width at half maximum (FWHM) energy resolution of the block detectors were 22.24±3.36% for “A” and 30.67±5.37% for “B”. The FWHM of the full block timing resolution of the inner/outer layer was 1.4 ns/1.2 ns for detector “A” and 1.8 ns/1.4 ns for “B”. The performance of the crystal position profile, the energy, and timing resolution indicate that configuration “A” is more appropriate for a mouse brain PET/MRI system.
关键词： PET/MRI,Depth of interaction,brain,small animal brain imaging,PET/RF,integrated MRI-coil,preclinical imaging,PET
更新于2025-09-19 17:15:36
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First prototyping of a dedicated PET system with the hemisphere detector arrangement
摘要： A strong demand is expected for high-sensitivity, high-resolution, and low-cost brain positron emission tomography (PET) imaging for early diagnosis of dementia as well as for general neuroscience studies. Therefore, we have proposed novel geometries of a hemisphere detector arrangement for high-sensitivity brain imaging, in which an add-on detector at the chin position or neck position helps in sensitivity uniformity improvement. In this study, we developed the first prototype system for proof-of-concept using 4-layer depth-of-interaction detectors, each of which consisted of 16×16×4 Zr-doped GSO crystals with dimensions of 2.8×2.8×7.5 mm3 and a high-sensitivity 64-channel flat-panel photomultiplier tube. We used 47 detectors to form a hemisphere detector with a hemisphere shape of 25 cm inner diameter and 50 cm outer diameter, and we used seven detectors for each of the add-on detectors. The hemisphere detector was realized by multiple rings having different numbers of detectors and a cross-shaped top detector unit covering the top. Performance evaluation showed uniform spatial resolutions of 3-4 mm by the filtered back-projection method. Peak sensitivity was measured as more than 10% at a region near the top of the head, which was achieved with the help of the top detector unit. In addition, using the prototype system, we performed the first FDG clinical test with a healthy volunteer. The results showed that the proposed geometries had high potential for realizing high-sensitivity, high-resolution, and low-cost brain PET imaging. As for the add-on detector position, it was shown that the neck position resulted in higher sensitivity and wider field of view (FOV) than the chin position because the add-on detector at the neck position can be placed continuously to the hemisphere detector and close to the FOV.
关键词： brain imaging,helmet-type PET,dementia,positron emission tomography,brain PET,depth-of-interaction
更新于2025-09-19 17:15:36
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Fluorine-18 click radiosynthesis and MicroPET/CT evaluation of a small peptide-a potential PET probe for carbonic anhydrase IX
摘要： Carbonic anhydrase IX (CA IX) is the first carbonic anhydrase found to be associated with cancer that is over-expressed in a variety of human solid tumors. As a surrogate marker for hypoxia, the expression of CA IX is strongly upregulated in hypoxic tumors by hypoxia and hypoxia-inducible factor 1a (HIF-1a). In our pursuit of a CA IX-specific PET probe, we designed and synthesized a peptide-based CA IX imaging probe by the efficient click reaction of 1,3-dipolar cycloaddition of terminal alkynes and organic azides. The probe 18F-CA IX-P1-4-10 was obtained with a radiochemical yield of 35-45% (n = 5) and radiochemical purity of >99% in 70-80 min (HPLC purification time included). 18F-CAIX-P1-4-10 had good stability in phosphate buffered saline (PBS), but about 51% peptide degradation was detected in new-born calf serum (NBCS) after incubation. Preliminary microPET/CT experiments demonstrated a specific uptake of 18F-CA IX-P1-4-10 in HT29 tumor and the uptake of 18F-CA IX-P1-4-10 was blocked by peptide CA IX-P1-4-10-Yne pretreatment. Immunohistochemical staining and western blotting studies confirmed the HT29 tumor was CA IX-positive which further proved tumor accumulation of 18F-CA IX-P1-4-10 was correlated with CA IX expression. The results suggest that 18F-CA IX-P1-4-10 is a promising PET tracer for the specific imaging of CA IX-expressing tumors at the molecular level.
关键词： peptide,tumor hypoxia,18F-labeling,Carbonic anhydrase IX,PET imaging
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Florbetapir Image Analysis for Alzheimer's Disease Diagnosis
摘要： Over decades Alzheimer’s disease (AD) remains without decent cure, and only disease-modifying methods are available. This paper is devoted to the analysis of amyloid-PET images with florbetapir (18F-AV-45) tracer to detect the presence of AD or Mild Cognitive Impairment (MCI). The first part of the article dedicated to image processing pipeline, specifically, spacial normalisation and feature extraction. The second part is devoted to the development of the multiclass classifier with deep learning methods. In particular, deep neural network was developed to distinguish three stages: health control (HC), MCI and AD. After tuning and training a neural network, the final specificity of 78% and sensitivity of 90% has been achieved.
关键词： Deep learning,Florbetapir,PET imaging,Alzheimer's disease,Amyloid Imaging
更新于2025-09-19 17:15:36
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Progress of Coordination and Utilization of Zirconium-89 for Positron Emission Tomography (PET) Studies
摘要： Radiometals have been commonly used in medical applications, and utilization of such metals continues to be an attractive research area. In particular, a variety of radiometals have been developed and implemented for molecular imaging. For such applications, 89Zr has been one of the most interesting radiometals currently used for tumor targeting. Several chemical ligands were developed as 89Zr chelators, and new coordinating methods have also been developed more recently. In addition, immuno-positron emission tomography (PET) studies using 89Zr-labeled monoclonal antibodies have been performed by several scientists. In this review, recent advances to the coordination of 89Zr and the utilization of 89Zr in PET studies are described.
关键词： 89Zr,Ligand,Positron emission tomography (PET),Coordination
更新于2025-09-19 17:15:36