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18F-FDG PET/TC para la estadificación y la delineación del volumen de radioterapia en el cáncer de cabeza y cuello
摘要： Purpose: The aim is to investigate the use of 18F-FDG (fluorine-18 fluorodeoxyglucose) PET/CT in head and neck cancer (HNC) staging and its effect on the therapeutic strategy and radiotherapy (RT) planning. Methods and materials: One hundred patients with HNC were included. Primary tumor sites: 18% oral cavity, 20% oropharynx, 12% hypopharynx, 11% nasopharynx, 37% larynx, 2% paranasal sinuses. Patients were staged according to the American Joint Committee of Cancer 7th edition. Stage: 5% stage I, 7% stage II, 14% stage III, 61% stage IVA, 7% stage IVB and 6% stage IVC. A contrast-enhanced CT and a 18F-FDG PET/CT acquired under RT position were performed. Both exams were compared to analyze patients' staging reclassification. Changes in therapeutic strategy were analyzed. Results: 18F-FDG PET/CT detected 6 distant metastases and treatment intention changed to palliative. Eight synchronous tumors were detected; one received palliative treatment. 18F-FDG PET/CT reclassified cTNM staging in 27 patients. Tumor extension changed in 28 (14% up-staged; 14% down-staged), implying a change in GTV (Gross Tumor Volume) delineation. Nodal detection was reclassified in 47 patients: 8 patients down-staged (N2C to N2A/N2B/N1) and 2 were false positive. Nineteen patients were false negatives and 5 staged as N+ (N1/N2A/N2B) turned out into N2C. These staging modifications imply adapting the nodal volume to be irradiated. Conclusions: 18F-FDG PET/CT reclassification was higher than 10% in almost all categories studied (cTNM, tumor extension and nodal disease) and detects more metastases and synchronous tumors than conventional studies, which has an impact on the therapeutic patient management and RT planning.
关键词： Head and neck cancer,18F-FDG PET/CT,Radiotherapy planning,Staging
更新于2025-09-23 15:22:29
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Caracterización y simulación de ruido en las imágenes de PET reconstruidas con OSEM: desarrollo de un método para la generación de imágenes sintéticas
摘要： Introduction: The goals of the study are to characterize imaging properties in 2D PET images reconstructed with the iterative algorithm ordered-subset expectation maximization (OSEM) and to propose a new method for the generation of synthetic images. Material and methods: The noise is analyzed in terms of its magnitude, spatial correlation, and spectral distribution through standard deviation, autocorrelation function, and noise power spectrum (NPS), respectively. Their variations with position and activity level are also analyzed. This noise analysis is based on phantom images acquired from 18F uniform distributions. Experimental recovery coefficients of hot spheres in different backgrounds are employed to study the spatial resolution of the system through point spread function (PSF). The NPS and PSF functions provide the baseline for the proposed simulation method: convolution with PSF as kernel and noise addition from NPS. Results: The noise spectral analysis shows that the main contribution is of random nature. It is also proven that attenuation correction does not alter noise texture but it modifies its magnitude. Finally, synthetic images of 2 phantoms, one of them an anatomical brain, are quantitatively compared with experimental images showing a good agreement in terms of pixel values and pixel correlations. Thus, the contrast to noise ratio for the biggest sphere in the NEMA IEC phantom is 10.7 for the synthetic image and 8.8 for the experimental image. Conclusions: The properties of the analyzed OSEM-PET images can be described by NPS and PSF functions. Synthetic images, even anatomical ones, are successfully generated by the proposed method based on the NPS and PSF.
关键词： PET,Autocorrelation function,OSEM,Iterative reconstruction,Noise power spectrum,Point spread function
更新于2025-09-23 15:22:29
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New Dynamic Photo-Electro-Thermal Modeling of Light-Emitting Diodes with Phosphor Coating as Light Converter
摘要： Phosphor-coated light-emitting diode (PC-LED) is the dominant LED technology for public lighting. This paper presents a comprehensive theory for analyzing and modeling phosphor coating in white light-emitting diodes (LEDs) as a dynamic light converter. The new PC-LED model not only obeys the traditional diode equation, it includes the energy-storage and transient effects of the phosphor coating. Major control variables include energy storage in and the luminous flux from the phosphor coating. This new model enables the dynamic variations of luminous flux and energy storage and power loss in phosphor-coating to be accurately predicted. Part-1 of this paper provides the details of the theory and analysis leading to the new PC-LED model under the framework of the photo-electro-thermal theory. Details of the model parameter determination, model setup and experimental verification are included in Part-2. The model offers the important power loss equation of the phosphor coating which highlights the factors affecting the heat loss and the coating’s blackening effects. This equation can be used by engineers to design LED drivers in order to reduce the coating temperature and the blackening effects and to prolong LED lifetime.
关键词： Phosphor-coated light-emitting diodes (PC-LED),flux capacitor,light converter.,photo-electro-thermal (PET) theory,dynamic model of PC-LED
更新于2025-09-23 15:22:29
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Primary Pulmonary Low-Grade Angiosarcoma Characterized by Mismatch between <sup>18</sup> F-FDG PET and Dynamic Contrast-Enhanced CT
摘要： We report a rare case of primary pulmonary low-grade angiosarcoma on dynamic contrast-enhanced CT and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT imaging. A 38-year-old, asymptomatic woman was hospitalized because of an abnormality on chest radiography. A dynamic contrast-enhanced chest CT showed a 1.2 cm-sized irregular-margined nodule with strong and persistent enhancement in the right lower lobe. The lesion had low metabolic activity on an 18F-FDG PET/CT scan. The patient underwent a wedge resection for the lesion, and pathology revealed a primary pulmonary low-grade angiosarcoma.
关键词： Primary pulmonary angiosarcoma,Dynamic contrast-enhanced CT,Low-grade,18F-FDG PET/CT
更新于2025-09-23 15:22:29
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18F-FDG uptake in the normal appendix in adults: PET/CT evaluation
摘要： Objective This study aimed to determine the level of 18F fluorodeoxyglucose (18F-FDG) activity in the normal adult appendix using positron emission tomography/computed tomography (PET/CT). Materials and methods We performed a retrospective review of PET/CT images using 18F-FDG in 563 consecutive asymptomatic adult patients without appendiceal pathology. We excluded 257 patients for an undetected or obscured appendix and three patients for appendicitis found on CT imaging. FDG uptake in the appendix was qualitatively and quantitatively assessed. The maximum standardized uptake value (SUVmax) was calculated for quantitative analysis with SUVmax of the normal liver for comparison. A total of 303 patients (200 males, 103 females, mean age of 66 years) were included in this study. Medical charts and histories were evaluated for patients who showed positive FDG accumulation. Pearson’s correlations between appendiceal SUVmax and age, body mass index, and blood glucose levels were analyzed. Results The mean appendiceal SUVmax was 1.14 (range 0.52–5.12) with an appendix-to-liver SUVmax ratio of 0.34 (range 0.06–1.28). Three patients qualitatively showed a positive FDG accumulation with appendiceal SUVmax greater than 3.00. There were no correlations between appendiceal SUVmax and age, body mass index, or blood glucose levels. Conclusions FDG in the normal adult appendix shows a low activity level and is lower compared with normal liver. However, the normal appendix can rarely show high FDG accumulation. In such cases, differentiation from appendiceal pathology solely by PET/CT images would be difficult.
关键词： Normal variants,Adult,PET/CT,Appendix
更新于2025-09-23 15:22:29
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?Puede la tomografía por emisión de positrones ayudar en la caracterización de la enfermedad inmunomediada del oído interno?
摘要： Introduction: To evaluate the utility of 18F-FDG PET/TC as an imaging tool for the characterization of immune-mediated inner ear disease (IMIED), providing measurements of the inner ear region activity as well as detecting possible involvement of other organs. Material and methods: The study included 28 patients with IMIED and 4 sex-matched and age-matched control subjects with no history of ear disease. Eighteen patients were considered to be suffering from primary IMIED and 10 patients from secondary. PET/CT scans with 18F-FDG were performed to assess systemic involvement as well as inner ear region activity. Interpretation of PET/CT scans was performed independently by 2 nuclear medicine physicians blinded to clinical history. In order to assess inter-rater agreement before performing the analysis of the inner ear, different Bland & Altman plots and the intraclass correlation coefficients were estimated. Results: Different metabolically active foci findings were reported in 13 patients. Four patients diagnosed as primary IMIED showed thyroid and aorta activity. Regarding the inner-ear semiquantitative analysis, the inter-rater agreement was not sufficiently high. Comparisons between groups, performed using Mann–Whitney test or Kruskal–Wallis tests, showed no differences. Conclusions: The study showed 18F-FDG PET/TC could be an important tool in the evaluation of IMIED as it can support the characterization of this entity providing the diagnosis of unknown or underestimated secondary IMIED. Nevertheless, we consider PET is not an adequate tool to approach the inner ear because of the small size and volume of the cochlea which makes the assessment very difficult.
关键词： Inner ear,Systemic autoimmune disease,PET,Immune-mediated hearing loss,FDG
更新于2025-09-23 15:22:29
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Eficacia de la imagen precoz con 68Ga-PSMA-I&T para la discriminación de lesiones en los pacientes con cáncer de próstata
摘要： Objective: 68Ga-PSMA-uptake shows accumulation in the malignant lesions of prostate cancer patients as early as 5 min p.i. Studies indicate the value of adding an early image of the pelvis to the imaging protocol of 68Ga-PSMA-11 PET/CT scan showed contradictory results. In this study we planned to assess the significance of an additional early imaging in 68Ga-PSMA-I&T PET/CT imaging in prostate cancer patients. Materials and methods: A total of 35 prostate cancer patients referred to 68Ga-PSMA-I&T PET/CT imaging for restaging of the disease due to suspicion of relapse after definitive therapy were enrolled. First an early static pelvic image was obtained at a maximum of 300 s following injection of the radiotracer. Sixty minutes postinjection a whole-body PET/CT scan was conducted with an emission time of 3 min per bed position. The lesions which were categorized as local recurrence, bone lesion and lymph node metastasis in the early images, were compared with the late images in terms of number of lesions detected and SUVmax values. Results: 68Ga-PSMA-I&T PET/CT was positive in 23 of 35 patients (65.7%). A pathological uptake was observed in the prostatic bed site, in the pelvic lymph nodes, and in the bones in 17 patients (48.5%), 12 patients (34.2%), and 13 patients (37.1%), respectively. In one patient, focal pathological increased uptake in the prostatic bed with a SUVmax value of 5.8 was detected but this lesion disappeared in the late images. The average SUVmax values of the lesions in the prostatic bed were 13.7 ± 12.1 versus 26.3 ± 23.8 in the 5 min and 60 min studies respectively (p < 0.001). In one patient, the pathological uptake in the lymph node in the early study cleared in the late study, whereas in another accumulation of activity was detected in a pelvic lymph node in the late study, while there was no lymph node detected in the early study. The average SUVmax values of the lymph nodes were 12.1 ± 8.8 versus 26.3 ± 22.6 in the 5 min and 60 min studies respectively (p < 0.001). The average SUVmax values of the bone lesions were 11.4 ± 6.9 versus 15 ± 10.7 in the 5 min and 60 min studies respectively. Conclusion: Our study is the first in the literature to evaluate the impact of adding an early static pelvic image to the 68Ga-PSMA-I&T scan, in the detection rate of the lesions. Although there was no marked discordance between the 2 sets of images, the addition of an early image to the imaging protocol of 68Ga-PSMA-I&T scan would increase the efficacy of detection of malignant lesions in the pelvis, which might show rapid clearance and has the risk of being masked by the urinary system activity.
关键词： Prostate-specific membrane antigen,68Ga-PSMA-I&T,PET/CT,Lymph node metastases,Prostate cancer
更新于2025-09-23 15:22:29
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Synthesis and <i>in vivo</i> evaluation of a novel PET radiotracer for imaging of synaptic vesicle glycoprotein 2A (SV2A) in non-human primates
摘要： Structural disruption and alterations of synapses are associated with many brain disorders, including Alzheimer’s disease, epilepsy, depression and schizophrenia. We have previously developed the PET radiotracer 11C-UCB-J for imaging and quantification of synaptic vesicle glycoprotein 2A (SV2A) and synaptic density in non-human primates and humans. Here we report the synthesis of a novel radiotracer 18F-SDM-8 and its in vivo evaluation in rhesus monkeys. The in vitro binding assay of SDM-8 showed high SV2A binding affinity (Ki = 0.58 nM). 18F-SDM-8 was prepared in high molar activity (241.7 MBq/nmol) and radiochemical purity (> 98%). In the brain, 18F-SDM-8 displayed very high uptake with peak standardized uptake value greater than 8, and fast and reversible kinetics. A displacement study with levetiracetam and blocking studies with UCB-J and levetiracetam demonstrated its binding reversibility and specificity towards SV2A. Regional binding potential values were calculated and ranged from 0.8 in the brainstem to 4.5 in the cingulate cortex. Comparing to 11C-UCB-J, 18F-SDM-8 displayed the same attractive imaging properties: very high brain uptake, appropriate tissue kinetics, and high levels of specific binding. Given the longer half-life of F-18 and the feasibility for central production and multi-site distribution, 18F-SDM-8 holds promise as an excellent radiotracer for SV2A and as a biomarker for synaptic density measurement in neurodegenerative diseases and psychiatric disorders.
关键词： UCB-J,18F-SDM-8,PET,SV2A,non-human primates,synaptic density
更新于2025-09-23 15:21:21
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Site-specific chelator-antibody conjugation for PET and SPECT imaging with radiometals
摘要： Antibodies and their derivatives radiolabelled with positron- and gamma-emitting radiometals enable sensitive and quantitative molecular Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) imaging of antibody distribution in vivo. Chelators that are covalently attached to antibodies allow radiolabelling with metallic PET and SPECT radioisotopes. Conventional strategies for chelator-protein conjugation generate heterogeneous mixtures of bioconjugates that can exhibit reduced affinity for their targets, and undesirable biodistribution and pharmacokinetics. Recent advances in bioconjugation technology enable site-specific modification to generate well-defined constructs with superior properties. Herein we survey existing site-specific chelator-protein conjugation methods. These include chelator attachment to cysteines/disulfide bonds or the glycan region of the antibody, enzyme-mediated chelator conjugation, and incorporation of sequences of amino acids that chelate the radiometal. Such technology will allow better use of PET and SPECT imaging in the development of antibody-based therapies.
关键词： antibody,radiometals,PET,chelator,site-specific conjugation,SPECT,molecular imaging
更新于2025-09-23 15:21:21
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Integrin α <sub/>γ</sub> β <sub/>3</sub> -targeted [ <sup>64</sup> Cu]CuS Nanoparticles for PET/CT Imaging and Photothermal Ablation Therapy
摘要： Copper sulfide (CuS) nanoparticles have been considered one of the most clinical relevant nanosystems because of their straightforward chemistry, small particle size, low toxicity, and intrinsic theranostic characteristics. In our previous studies, radioactive [64Cu]CuS nanoparticles were successfully developed to be used as efficient radiotracers for positron emission tomography and for photothermal ablation therapy of cancer cells using near-infrared laser irradiation. However, the major challenge of CuS nanoparticles as a theranostic platform is the lack of a means for effective targeted delivery to the tumor site. To overcome this challenge, we designed and synthesized angiogenesis-targeting [64Cu]CuS nanoparticles, which are coupled with cyclic RGDfK peptide [c(RGDfK)] through polyethylene glycol (PEG) linkers using click chemistry. In assessing their tumor-targeting efficacy, we found that the tumor uptakes of [64Cu]CuS-PEG-c(RGDfK) nanoparticles at 24 h after intravenous injection were significantly greater (8.6%±1.4% injected dose/gram of tissue) than those of nontargeted [64Cu]CuS-PEG nanoparticles (4.3%±1.2% injected dose/gram of tissue, p < 0.05). Irradiation of tumors in mice administered [64Cu]CuS-PEG-c(RGDfK) nanoparticles induced 98.7% necrotic areas. In contrast, irradiation of tumors in mice administered non-targeted CuS-PEG nanoparticles induced 59% necrotic areas (p < 0.05). The angiogenesis-targeting [64Cu]CuS nanoparticles may serve as a promising platform for image-guided ablation therapy with high efficacy and minimal side effects in future clinical translation of this novel class of multifunctional nanomaterials.
关键词： PET/CT imaging,RGD peptide,Copper sulfide nanoparticles,photothermal ablation therapy,integrin αvβ3,theranostics
更新于2025-09-23 15:21:21