Thematische Bibliographien / Diffusion CT

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Auswahl der wissenschaftlichen Literatur zum Thema „Diffusion CT“

Autor: Grafiati

Veröffentlicht am 25. Mai 2024

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Zeitschriftenartikel zum Thema "Diffusion CT"

Da Silva, Marly Terezinha Quadri Simões, und Wellington Mazer. „Diffusion coefficient and tortuosity: Brownian Motion“. CONTRIBUCIONES A LAS CIENCIAS SOCIALES 16, Nr. 9 (28.09.2023): 18281–302. http://dx.doi.org/10.55905/revconv.16n.9-264.

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The objective of this research is to determine the chloride ion diffusion through Brownian motion using images. The research also aims at the search for diffusional physical tortuosity due to Brownian motion to understand the transport flow of the chloride ion. Through micro-CT scanned images of concrete samples, a 3D reconstruction is performed for the representative element and define its microscopic properties. The implementation of the Brownian motion of the chloride ion particles in the porous network of the representative element considered the initial diffusion coefficient defined by the Stokes-Einstein equation. The diffusion coefficient is an important parameter for predicting the depth of attack of the chloride ion and its displacement due to Brownian motion helps to define the tortuosity of this diffusive transport. The research used computational modeling with MATLAB® software. The results show diffusion due to Brownian motion and tortuousness.

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Guo, Huimin, Zhiwen Zhang, Li Wang, Shuzhan Yao, Shuaishuai Xu, Shulin Ma und Songtao Liu. „Diagnostic Significance of 18F-FDG PET/CT Imaging Coupled with Magnetic Resonance Imaging of the Entire Body for Bone Metastases“. Contrast Media & Molecular Imaging 2022 (27.09.2022): 1–7. http://dx.doi.org/10.1155/2022/7717398.

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Objective. To see if 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) imaging paired with MR diffusion imaging can help doctors diagnose bone metastases. Methods. From September 2020 to December 2021, a total of 30 individuals with probable bone metastases were recruited for the trial. With an average interval of four days, MAGNETIC resonance whole-body diffusion imaging (MR whole-body diffusion imaging) was performed on each of the 30 patients who had 18F-FDG PET/CT. The SUVmax values of the group with bone metastases were compared to those of the group without bone metastases. In this study, 18F-FDG PET/CT imaging, MR whole-body diffusion imaging, and their combination were examined. The researchers compared the results when 18F-FDG PET/CT imaging, whole-body MRI diffusion scans, and their combination indicated abnormal bone lesions. By comparing the diagnostic efficacy of 18F-FDG PET/CT imaging, MR whole-body diffusion imaging, and their combination, as well as accuracy, sensitivity, and specificity, the three techniques for diagnosing bone metastases will be evaluated for diagnostic usefulness. Results: the SUV max values of patients with bone metastases were significantly different from those of patients without bone metastases, as determined by 18F-FDG PET/CT imaging ( P < 0.05). Using 18F-FDG PET/CT imaging, MR whole-body diffusion imaging, and their combined detection of aberrant bone lesions in various areas, we found statistically significant differences. Conclusion. The use of 18F-FDG PET/CT imaging in conjunction with MR whole-body diffusion imaging in the diagnosis of bone metastases can be very helpful.

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Sigismondi, Paolo. „Exploring Translation Gaps: The Untranslatability and Global Diffusion of “Cool”“. Communication Theory 28, Nr. 3 (16.04.2018): 292–310. http://dx.doi.org/10.1093/ct/qtx007.

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Chae, Baek, Chang shik Choi, Seung-Hwa Kang und Yun-Cheol Heo. „Diffusion of television, wax and wane of community and family bond“. Communication Theories 14, Nr. 4 (31.12.2018): 139–82. http://dx.doi.org/10.20879/ct.2018.14.4.139.

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Chae, Baek, Seung-Hwa Kang und Yun-Cheol Heo. „Diffusion of telephone and changes in interpersonal relationship: An oral history study“. Communication Theories 15, Nr. 3 (30.09.2019): 105–51. http://dx.doi.org/10.20879/ct.2019.15.3.105.

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Morris, N. „A Comparative Analysis of the Diffusion and Participatory Models in Development Communication“. Communication Theory 13, >2 (01.05.2003): 225–48. http://dx.doi.org/10.1093/ct/13.2.225.

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Okazumi, Shinichi, Gaku Ohira, Koichi Hayano, Tomoyoshi Aoyagi, Shunsuke Imanishi und Hisahiro Matsubara. „Novel Advances in Qualitative Diagnostic Imaging for Decision Making in Multidisciplinary Treatment for Advanced Esophageal Cancer“. Journal of Clinical Medicine 13, Nr. 2 (22.01.2024): 632. http://dx.doi.org/10.3390/jcm13020632.

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Background: Recently, neoadjuvant therapy and the succeeding surgery for advanced esophageal cancer have been evaluated. In particular, the response to the therapy has been found to affect surgical outcomes, and thus a precise evaluation of treatment effect is important for this strategy. In this study, articles on qualitative diagnostic modalities to evaluate tumor activities were reviewed, and the diagnostic indices were examined. Methods: For prediction of the effect, perfusion CT and diffusion MRI were estimated. For the histological response evaluation, perfusion CT, diffusion-MRI, and FDG-PET were estimated. For downstaging evaluation of T4, tissue-selective image reconstruction using enhanced CT was estimated and diagnostic indices were reviewed. Results: The prediction of the effect using perfusion CT with ‘pre CRT blood flow’ and diffusion MRI with ‘pre CRT ADC value’; the estimation of the histological response using perfusion CT with ‘post CRT blood flow reduction, using diffusion MRI with ‘post CRT ADC increasing’, and using FDG-PET with ‘post CRT SUV reduction’; and the downstaging evaluation of T4 using CT image reconstruction with ‘fibrous changed layer’ were performed well, respectively. Conclusions: Qualitative imaging modalities for prediction or response evaluation of neoadjuvant therapy for progressive esophageal cancer were useful for the decision making of the treatment strategy of the multidisciplinary treatment.

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Kim, Su-Beom, Soo Jin Song, Yeong Hyoen Yoo und Dar Oh Lim. „International Comparative Analysis of Advanced Diagnostic Imaging Equipment Demand Characteristics Using the Bass Diffusion Model“. Journal of Health Informatics and Statistics 49, Nr. 1 (28.02.2024): 27–34. http://dx.doi.org/10.21032/jhis.2024.49.1.27.

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Objectives: This paper proposed the direction of future supply and demand management policies through demand prediction and demand characteristics analysis of advanced diagnostic imaging equipment using new medical technology.Methods: This study used the Bass Diffusion Model to analyze demand characteristics for advanced diagnostic imaging equipment. Derived diffusion coefficients were applied for medium to long-term demand predictions (2021-2050). Parameter estimation employed non-linear regression analysis (SPSS 27.0). Demand characteristics were further analyzed using the ratio of the Bass model’s innovation to imitation coefficients for each country and device.Results: Comparing the imitation coefficients (q/p ratio) for computed tomography (CT) and magnetic resonance imaging (MRI) among South Korea, the United States, and Japan, South Korea has the highest q/p ratio for both CT and MRI. This implies that the influence of opinion leaders and group pressure is relatively more significant in South Korea, particularly in CT purchases. In the demand prediction results, South Korea’s q/p ratio for CT and MRI is notably larger, suggesting that institutional pressures and collective decision-making, rather than individual clinical decisions, play a significant role in the purchase of advanced diagnostic imaging Equipment. The q/p ratio for advanced diagnostic imaging Equipment in South Korea is higher than in other countries, reflecting a large power distance in the adoption of these technologies.Conclusions: This study utilizes the Bass Diffusion Model to predict the demand for advanced diagnostic imaging equipment in South Korea, Japan, and the United States. Findings highlight that imitation, not innovation, is the main driver of diffusion, with South Korea showing a faster adoption rate for CT and MRI. The study identifies factors influencing diffusion in South Korea, noting the impact of the quantity system on CT and the absence of influence on MRI. CT diffusion is positively linked to the quantity-based payment system, while MRI remains unaffected.

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Demeestere, Jelle, Carlos Garcia-Esperon, Pablo Garcia-Bermejo, Fouke Ombelet, Patrick McElduff, Andrew Bivard, Mark Parsons und Christopher Levi. „Evaluation of hyperacute infarct volume using ASPECTS and brain CT perfusion core volume“. Neurology 88, Nr. 24 (17.05.2017): 2248–53. http://dx.doi.org/10.1212/wnl.0000000000004028.

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Objective:To compare the accuracy of Alberta Stroke Program Early Computed Tomography Score (ASPECTS) and CT perfusion to detect established infarction in acute anterior circulation stroke.Methods:We performed an observational study in 59 acute anterior circulation ischemic stroke patients who underwent brain noncontrast CT, CT perfusion, and MRI within 100 minutes from CT imaging. ASPECTS scores were calculated by 4 blinded vascular neurologists. The accuracy of ASPECTS and CT perfusion core volume to detect an acute MRI diffusion lesion of ≥70 mL was evaluated using receiver operating characteristics analysis and optimum cutoff values were calculated using Youden J.Results:Median ASPECTS score was 8 (interquartile range [IQR] 5–9). Median CT perfusion core volume was 22 mL (IQR 10.4–71.9). Median MRI diffusion lesion volume was 24.5 mL (IQR 10–63.9). No significant difference was found between the accuracy of CT perfusion and ASPECTS (c statistic 0.95 vs 0.87, p value for difference = 0.17). The optimum ASPECTS cutoff score to detect a diffusion-weighted imaging lesion ≥70 mL was <7 (sensitivity 0.74, specificity 0.86, Youden J = 0.60) and the optimum CT perfusion core volume cutoff was ≥50 mL (sensitivity 0.86, specificity 0.97, Youden J = 0.84). The CT perfusion core lesion covered a median of 100% (IQR 86%–100%) of the acute MRI lesion volume (Pearson R = 0.88; R2 = 0.77).Conclusions:We found no significant difference between the accuracy of CT perfusion and ASPECTS to predict hyperacute MRI lesion volume in ischemic stroke.

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Sato, Akira, und Koichi Ikeda. „Visualization of diffusion phenomena in porous media by means of X-ray computed tomography (CT) scanning“. Canadian Geotechnical Journal 52, Nr. 10 (Oktober 2015): 1448–56. http://dx.doi.org/10.1139/cgj-2014-0451.

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The migration of water and contamination materials in rock structures is a significant issue in projects that utilize deep underground locations such as “carbon-dioxide capture and storage” (CCS) and disposal of high-level nuclear waste. These phenomena are also important in the area of preservation of stone structures of cultural heritage signficance, as such stone structures are usually located outside, exposed to wind and rain. The migration of contamination materials in the underground environment, especially in porous rock mass, is governed mainly by water permeation and diffusion. In this study, one-dimensional diffusion testing was conducted and the process in the porous materials was visualized by X-ray computed tomography (CT) scanning. Diffusion is the process caused by the concentrate or density gradient, and is a suitable phenomenon for X-ray CT analysis. In this paper, information related to diffusion is extracted from X-ray CT image data and the distribution of concentration is estimated. From the obtained density distribution, diffusion coefficients are evaluated. One-dimensional permeation tests were also conducted and intrinsic permeabilities of porous materials are evaluated, then the relation between diffusion coefficients and intrinsic permeability is discussed.

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Dissertationen zum Thema "Diffusion CT"

Mosavi, Firas. „Whole-Body MRI including Diffusion-Weighted Imaging in Oncology“. Doctoral thesis, Uppsala universitet, Enheten för radiologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-209777.

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Cancer is one of the major causes of worldwide mortality. Imaging plays a vital role in the staging, follow-up, and evaluation of therapeutic response in cancer patients. Whole-body (WB) magnetic resonance imaging (MRI), as a non-ionizing imaging technique, is a promising procedure to assess tumor spreading in a single examination. New MRI technological developments now enable the application of diffusion-weighted imaging (DWI) of the entire body. DWI reflects the random motion of water molecules and provides functional information of body tissues. DWI can be quantified with the use of the apparent diffusion coefficient (ADC). The aim of this dissertation was to demonstrate the value of WB MRI including DWI in cancer patients. WB MRI including DWI, 18F-NaF PET/CT, and bone scintigraphy was performed on 49 patients with newly diagnosed, high-risk prostate cancer, for the purpose of detecting bone metastases. WB DWI showed higher specificity, but lower sensitivity compared to 18F-NaF PET/CT. In addition, WB MRI including DWI, and CT of the chest and abdomen was performed in 23 patients with malignant melanoma. We concluded that WB MRI could not completely supplant CT for the staging of malignant melanoma, especially with respect to the detection of lesions in the chest region. In this study, WB MRI and DWI were able to detect more bone lesions compared to CT, and showed several lesions outside the CT field of view, reinforcing the advantage of whole-body examination. WB MRI, including DWI, was performed in 71 patients with testicular cancer. This modality demonstrated its feasibility for use in the follow-up of such patients. WB MRI, including DWI, and 18F-FDG PET-CT, were carried out in 50 patients with malignant lymphoma. Both these imaging modalities proved to be promising approaches for predicting clinical outcomes and discriminating between different subtypes of lymphomas. In conclusion, WB MRI, including DWI, is an evolving technique that is continuing to undergo technical refinement. Standardization of image acquisition and analysis will be invaluable, allowing for more accurate comparison between studies, and widespread application of this technique in clinical practice. Both WB MRI, including DWI and PET/CT, have their particular strengths and weaknesses in the evaluation of metastatic disease. DWI and PET/CT are different functional techniques, so that combinations of these techniques may provide complementary and more comprehensive information of tumor tissue.

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Takahashi, Hiroaki, Yoshimi Seida und Mikazu Yui. „3D X-ray CT and diffusion measurements to assess tortuosity and constrictivity in a sedimentary rock“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191088.

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Takahashi, Hiroaki, Yoshimi Seida und Mikazu Yui. „3D X-ray CT and diffusion measurements to assess tortuosity and constrictivity in a sedimentary rock“. Diffusion fundamentals 11 (2009) 89, S. 1-11, 2009. https://ul.qucosa.de/id/qucosa%3A14061.

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A high-resolution, three-dimensional (3D) image of the interior of the sedimentary rock was obtained by means of nano-focus X-ray computer tomography (X-ray CT). Using computational methods to analyze the 3D microstructure of the rock, we presented the tortuosity and geometrical constrictivity. We also presented results on the tritiated water (HTO) diffusion tests and a mercury intrusion porosimetry (MIP) test performed on the rock. We have compared these results to understand the dominant parameters that control diffusion of HTO in the present system. These results suggest that the dominant parameters in the present system are not the constrictivity but the tortuosity and the diffusion-accessible porosity. The material considered in this study is the siliceous mudstones sampled from 500 m in depth at the Wakkanai formation around Horonobe underground research center in Hokkaido, Japan.

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Peyrat, Jean-Marc. „Comparison of cardiac anatomy and function : statistics on fibre architecture form DT-MRI and registration of 4D CT images“. Nice, 2009. http://www.theses.fr/2009NICE4053.

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Ce travail de thèse s'est consacré à la comparaison de l'anatomie et de la fonction cardiaques à partir d'images médicales. La première partie de la thèse se concentre sur l'anatomie cardiaque avec une étude statistique de l'architecture des fibres musculaires du cœur à partir d'imagerie par résonance magnétique du tenseur de diffusion (IRM-TD). Dans la deuxième partie est proposée une comparaison conjointe de l'anatomie et de la fonction cardiaque par le recalage non-linéaire spatiotemporel de deux séquences 4D CT de différents patients ou du même patient à différents instants. L'architecture des fibres cardiaques, un arrangement spatial complexe des fibres localement liées les une aux autres pour former des plans appelés feuillets, joue un rôle essentiel dans le comportement électrique et mécanique du cœur, et donc de la fonction cardiaque. Nous avons proposé un cadre algorithmique pour réaliser une analyse statistique de l'architecture des fibres cardiaques à partir d'IRM-TD. La nouveauté de cette approche repose sur une analyse statistiques du premier et second ordre calculées directement sur les tenseurs de diffusion (matrices symétriques définies positives) utilisant la métrique Log-Euclidienne. La variabilité de l'orientation des fibres et feuillets au sein d'une population est ensuite extraite de la matrice de covariance des tenseurs de diffusion. Ce cadre algorithmique est appliqué à des données d'IRM-TD de cœurs chiens acquis ex vivo. Cette comparaison statistique inter-espèce fournit non seulement un modèle moyen (ou atlas) de l'architecture des fibres, mais révèle aussi une cohérence de l'orientation des fibres et une divergence de l'orientation des feuillets au sein de cette population de cœurs. L'atlas canin résultant est ensuite comparée à une donnée humaine rare d'IRM-TD acquise ex vivo et un modèle synthétique utilisé pour des simulations électromécaniques ou de l'analyse d'images. Cette comparaison inter-espèce préliminaire a révélé une bien meilleure similarité de l'orientation des fibres que des feuillets entre les cœurs humains et canins. Comparé à l'atlas canin, le modèle synthétique s'est quant a lui révélé limité pour une description complète et fidèle de l'architecture des fibres. L'acquisition de séquences d'images cardiaques permet d'observer le mouvement cardiaque et donc sa fonction, en plus de son anatomie. Afin de comparer cette fonction cardiaque, nous avons proposé un nouvel algorithme de recalage non-linéaire spatiotemporel de séquences d'images. Ce recalage spatiotemporal est découplé en un recalage temporel qui met en correspondance des événements physiologiques et en un recalage spatial qui quant à lui met en correspondance des points anatomiques tout en assurant une cohérence avec leurs mouvements respectifs. Cette cohérence est assurée par la définition de «contraintes de trajectoires» liant les transformations intra-séquences décrivant le mouvement cardiaque aux transformations inter-séquences décrivant les différences anatomiques à différents instants physiologiques. Sous ces contraintes de trajectoires, le problème de recalage spatial 4D est simplifié en un problème de recalage multicanal 3D résolu avec une nouvelle version des «Démons Diffeomorphes», appelée «Démons Diffeomorphes Multicanaux». Cette nouvelle méthode de recalage est appliquée au recalage inter-sujet de séquences 4D CT pour évaluation. Comparée à d'autres méthodes existantes, elle s'est révélée le meilleur compromis en terme de précision, de régularité spatiale et temporelle, ainsi que de temps de calcul. Un exemple d'application clinique possible du recalage non-linéaire spatiotemporal est proposé pour comparer l'anatomie et la fonction cardiaques avant et après thérapie. Pour cela, nous avons proposé d'étudier l'évolution au cours du cycle cardiaque des déformations des transformations inter-sujets que nous avons appelées «Déformations de Remodelage». Ces nouveaux indices cardiaques permettent notamment d'expliquer et de quantifier le remodelage ayant lieu après thérapie
In this thesis, we address the problem of comparing cardiac anatomy and function from medical images. The first part focuses on cardiac anatomy with a statistical study of cardiac fibre architecture from diffusion tensor magnetic resonance imaging (DT-MRI). The second part focuses on a joint comparison of cardiac anatomy and function with the nonlinear spatiotemporal registration of two 4D computed tomography (CT) sequences of different patients or of the same patient at different times. Cardiac fiber architecture, a complex spatial arrangement of myofibres locally bounded to each other to form planes called laminar sheets, plays an essential role in defining the electrical and mechanical behaviour of the heart, and thus in cardiac function. We propose a unified computational framework to perform a statistical analysis of cardiac fibre architecture from DT-MRI. The novelty of this framework lies on first- and second-order statistics directly computed on diffusion tensors (symmetric definite positive matrices) based on the Log-Euclidean metric. The variability of fibre and laminar sheet orientations among a population is then extracted from the covariance matrix of diffusion tensors. This computational framework is applied to a dataset of canine DT-MRI acquired ex vivo. This intra-species statistical comparison does not only provide an average model (or atlas) of cardiac fibre architecture, but also shows consistency of fibre orientation and discrepancies of laminar sheet orientation among this population of hearts. The resulting canine atlas is then compared to a rare single human DT-MRI acquisition ex vivo and a synthetic model used for electromechanical simulations or image analysis. This preliminary inter-species comparison shows a much better consistency of fibre orientation than laminar sheet orientation between human and canine hearts. Compared to the canine atlas, the synthetic model has showed to be limited for a complete and accurate description of cardiac fibre architecture. The acquisition of time-series of cardiac images gives the opportunity to observe cardiac motion and thus its function in addition to its anatomy. In order to compare this cardiac function, we propose a novel nonlinear spatiotemporal registration algorithm of time-series of images. The spatiotemporal registration is decoupled into a temporal registration that aims at mapping corresponding physiological events and into a spatial registration that aims at mapping corresponding anatomical points ensuring a consistency with their respective motion. This consistency is ensured by defining «trajectory constraints» linking intra-sequence transformations describing cardiac motion to inter-sequence transformations describing anatomical differences at different physiological times. Under these trajectory constraints, the 4D spatial registration problem is simplified to 3D multichannel registration problem solved using a new version of the «Diffeomorphic Demons», called the «Multichannel Diffeomorphic Demons». This new registration method is applied to the inter-subject registration of 4D cardiac CT sequences for evaluation. Its comparison to other existing methods shows that it is the best compromise between accuracy, spatial and temporal regularization, and computation times. A possible clinical application of the spatiotemporal nonlinear registration is then proposed to compare cardiac anatomy and function before and after therapy. We propose to study over a cardiac cycle the evolution of strains of inter-sequence transformations that we called «Remodeling Strains». These new cardiac indices can be used to explain and quantify remodeling processes after therapy

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Peyrat, Jean-Marc. „Comparaison de l'Anatomie et de la Fonction Cardiaque : Statistiques sur l'Architecture des Fibres et Recalage d'Images 4D CT“. Phd thesis, Université de Nice Sophia-Antipolis, 2009. http://tel.archives-ouvertes.fr/tel-00635292.

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Ce travail de thèse s'est consacré à la comparaison de l'anatomie et de la fonction cardiaques à partir d'images médicales. Une première partie se concentre sur l'anatomie cardiaque avec une étude statistique de l'architecture des bres musculaires du c÷ur à partir d'IRM de tenseur de di usion. Dans la deuxième partie est proposée une comparaison la fonction cardiaque de di érents patients ou du même patient a di érents instants par le recalage spatiotemporel de séquences 4D CT. La complexe organisation des bres musculaires cardiaques a un rôle très important dans le comportement électrique et mécanique du c÷ur. Pour étudier cette architecture des bres, nous avons proposé de nouveaux outils algorithmiques d'analyse statistique d'IRM de tenseurs de di usion. La nouveauté de cette approche est de réaliser cette analyse statistique directement sur les tenseurs de di usion l'a où la plupart des études statistiques se font sur des vecteurs ou angles d'orientation décrivant les directions des bres et des feuillets. La variabilité de l'orientation des bres et des feuillets est ensuite directement donnée par la matrice de covariance des tenseurs de di usion de laquelle sont extraites les variabilités des vecteurs propres. L'application de ces outils a une base de données d'IRM de tenseur de di usion de c÷urs de chiens acquis ex vivo a permis d'obtenir un atlas de l'architecture des bres mais aussi de révééler une cohérence de l'orientation des bres et une plus grande variabilité de l'orientation des feuillets. Ensuite, nous avons comparé l'atlas de c÷urs de chien à un c÷ur humain et un modèle synthétique couramment utilisé pour des simulations électromé- caniques ou l'analyse d'images cardiaques. Le c÷ur humain s'est révélé plus proche des c÷urs de chien au niveau de l'orientation des bres que de celle des feuillets. Le modèle synthétique quant à lui s'est montré trop simple pour décrire en détails la complexité de l'architecture des bres. L'acquisition de séquences d'images cardiaques permet d'observer le mouvement cardiaque et donc sa fonction. Nous avons proposé un nouvel algorithme de recalage nonlin éaire spatiotemporel de séquences d'images qui permet de comparer cette fonction cardiaque. Le recalage temporel assure la mise en correspondance d'instants physiologiques similaires. Le recalage spatial quant à lui doit assure une cohérence entre le mouvement des points physiques intra-séquence et leur mise en correspondance inter-séquence. Cette cohérence est assurée par les contraintes de trajectoires liant les transformations intras équences décrivant le mouvement cardiaque aux transformations inter-séquences décrivant les di érences anatomiques au cours du temps. Sous ces contraintes de trajectoires, le recalage spatial 4D est simpli é en un recalage multicanal 3D résolu avec une nouvelle version des Demons Di eomorphes Multicanaux. Cette méthode de recalage spatiotemporel est appliquée au recalage inter-sujet de séquences 4D CT pour évaluation. Comparée a d'autres techniques existantes, cette technique de recalage s'est révélée le meilleur compromis en terme de précision, de régularité spatiale et temporelle, mais aussi de temps de calcul. Un exemple d'application possible du recalage spatiotemporal est proposé avec la comparaison de l'anatomie et de la fonction cardiaques avant et après thérapie.

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Nunn, Jacob. „Investigations of Partial Gas Saturation on Diffusion in Low-permeability Sedimentary Rocks“. Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38396.

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The effect of partially saturated conditions on aqueous diffusion was investigated on the Upper Ordovician Queenston Formation shale from the Michigan Basin of southwest Ontario, Canada. Effective diffusion coefficients (De) were determined for iodide tracer on duplicate cm-scale samples from a core segment. Partially saturated conditions were created with a new gas-ingrowth method that takes advantage of the variability of N2 solubility with pressure. The method is designed to create partially saturated pores, quantify the level of partial gas/brine saturation within the tracer-accessible pore space, and measure De under fully porewater-saturated and partially gas-saturated conditions for the same sample. X-ray radiography is used with an iodide tracer for quantifying the degree of partial saturation and measuring De. The saturated De values range from 2.8 x 10-12 to 3.1 x 10-12 m2/s. Following generation of a gas phase in the pores (average gas saturations of 4 to 6.7 %), De values decrease by 20 to 22 % relative to the porewater-saturated condition, indicating that the tortuosity factor (ratio of constrictivity to tortuosity) is sensitive to saturation. Suggesting that a small volume of the pore fraction is responsible for majority of the transport. The gas-ingrowth method was successful for generating partial gas saturation, but the distribution of the gas phase is non-uniform, with relatively high gas saturations near boundaries and lower saturations in the interior of the samples.

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Gu, Jing, und 谷静. „Multiparametric imaging using diffusion and dynamic-contrast enhanced MRI, and 18F-FDG PET/CT in the evaluation of primary rectal cancer andmalignant lymphoma“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47027174.

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Fabien, Aurélie Jessica. „Etude du couplage comportement hydromécanique – durabilité dans le béton de la structure : application à la maquette MAREVA“. Nantes, 2012. http://www.theses.fr/2012NANT2090.

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Maiwald, Bettina, Donald Lobsien, Thomas Kahn und Patrick Stumpp. „Is 3-Tesla Gd-EOB-DTPA-enhanced MRI with diffusion-weighted imaging superior to 64-slice contrast-enhanced CT for the diagnosis of hepatocellular carcinoma?“ Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-155190.

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Objectives: To compare 64-slice contrast-enhanced computed tomography (CT) with 3-Tesla magnetic resonance imaging (MRI) using Gd-EOB-DTPA for the diagnosis of hepatocellular carcinoma (HCC) and evaluate the utility of diffusion-weighted imaging (DWI) in this setting. Methods: 3-phase-liver-CT was performed in fifty patients (42 male, 8 female) with suspected or proven HCC. The patients were subjected to a 3-Tesla-MRI-examination with Gd-EOB-DTPA and diffusion weighted imaging (DWI) at b-values of 0, 50 and 400 s/mm2. The apparent diffusion coefficient (ADC)-value was determined for each lesion detected in DWI. The histopathological report after resection or biopsy of a lesion served as the gold standard, and a surrogate of follow-up or complementary imaging techniques in combination with clinical and paraclinical parameters was used in unresected lesions. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive values were evaluated for each technique. Results: MRI detected slightly more lesions that were considered suspicious for HCC per patient compared to CT (2.7 versus 2.3, respectively). ADC-measurements in HCC showed notably heterogeneous values with a median of 1.2±0.5×10−3 mm2/s (range from 0.07±0.1 to 3.0±0.1×10−3 mm2/s). MRI showed similar diagnostic accuracy, sensitivity, and positive and negative predictive values compared to CT (AUC 0.837, sensitivity 92%, PPV 80% and NPV 90% for MRI vs. AUC 0.798, sensitivity 85%, PPV 79% and NPV 82% for CT; not significant). Specificity was 75% for both techniques. Conclusions: Our study did not show a statistically significant difference in detection in detection of HCC between MRI and CT. Gd-EOB-DTPA-enhanced MRI tended to detect more lesions per patient compared to contrast-enhanced CT; therefore, we would recommend this modality as the first-choice imaging method for the detection of HCC and therapeutic decisions. However, contrast-enhanced CT was not inferior in our study, so that it can be a useful image modality for follow-up examinations.

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Cunningham, Dustin T. „Fusion of Multimodal Neuroimaging for Deep Brain Stimulation Studies“. The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337895443.

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Bücher zum Thema "Diffusion CT"

Gardner, Andrew, Grant L. Iverson, Paul van Donkelaar, Philip N. Ainslie und Peter Stanwell. Magnetic Resonance Spectroscopy, Diffusion Tensor Imaging, and Transcranial Doppler Ultrasound Following Sport-Related Concussion. Herausgegeben von Ruben Echemendia und Grant L. Iverson. Oxford University Press, 2015. http://dx.doi.org/10.1093/oxfordhb/9780199896585.013.12.

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Sport-related concussion has been referred to as a functional rather than a structural injury with neurometabolic and microstructural alterations reported in several studies. Accordingly, conventional neuroimaging techniques, such as computed tomography (CT) and structural magnetic resonance imaging (MRI), have limited value beyond ruling out structural injury such as a contusion or hemorrhage. This chapter presents a review of three neuroimaging techniques that offer insight into the connectivity and neurometabolic consequences of concussion. A number of studies have now been published using magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI)/diffusion-weighted imaging, and transcranial Doppler ultrasound (TCD) with varying findings. The results of these studies will be presented, together with current and possible future application of these techniques within the field of sport-related concussion.

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Glockner, James F., Kazuhiro Kitajima und Akira Kawashima. Magnetic resonance imaging. Herausgegeben von Christopher G. Winearls. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199592548.003.0015_update_001.

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Magnetic resonance imaging (MRI) provides excellent anatomic detail and soft tissue contrast for the evaluation of patients with renal disease. MRI needs longer scan time than computed tomography (CT); however, no radiation is involved. Gadolinium-based contrast agents (GBCAs) are used to help provide additional image contrast during MRI. MRI is indicated for characterization of renal mass, staging of malignant renal neoplasms, and determination of vena cava involvement by the renal tumour. Magnetic resonance (MR) angiography is widely accepted as a non-invasive imaging work-up of renal artery stenosis. MR urography is an alternative to CT urography to assess the upper urinary tract but does not identify urinary calculi. Diffusion-weighted imaging is a functional MR technique being used to characterize parenchymal renal disease and renal tumours. Nephrogenic systemic fibrosis is a rare but debilitating and potentially life-threatening condition which has been linked to exposure of GBCAs in patients with severe renal insufficiency. The risk versus benefit must be assessed before proceeding.

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Das, Raj, Susan Heenan und Uday Patel. Magnetic resonance imaging in urology. Herausgegeben von Michael Weston. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199659579.003.0134.

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Magnetic resonance imaging is essential for urological imaging. It offers excellent soft tissue contrast and resolution, allowing manipulation of tissue contrast with different image weighting and sequences. The multiplanar aspect of MRI allows image acquisition in different planes and degrees of obliquity to best exhibit pathology. The basic physics of MRI is explored initially with explanation of image weighting, sequences, and diffusion-weighted imaging. The chapter is then divided into renal, bladder, and prostate MRI imaging. The paragraphs on renal MRI outline renal mass analysis and include characterization and assessment of cystic and fat-containing lesions. Staging of renal carcinoma with MRI is also discussed, along with its advantages compared with CT staging. Throughout the text, the key diagnostic MRI features with each disease and organ, and the pitfalls and caveats of MRI imaging are emphasized.

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Buchteile zum Thema "Diffusion CT"

Ferrozzi, Francesco, Giacomo Garlaschi und Davide Bova. „Modalities of Metastatic Diffusion“. In CT of Metastases, 5–10. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-642-59595-0_3.

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Ali, Hazrat, Shafaq Murad und Zubair Shah. „Spot the Fake Lungs: Generating Synthetic Medical Images Using Neural Diffusion Models“. In Communications in Computer and Information Science, 32–39. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-26438-2_3.

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AbstractGenerative models are becoming popular for the synthesis of medical images. Recently, neural diffusion models have demonstrated the potential to generate photo-realistic images of objects. However, their potential to generate medical images is not explored yet. We explore the possibilities of synthesizing medical images using neural diffusion models. First, we use a pre-trained DALLE2 model to generate lungs X-Ray and CT images from an input text prompt. Second, we train a stable diffusion model with 3165 X-Ray images and generate synthetic images. We evaluate the synthetic image data through a qualitative analysis where two independent radiologists label randomly chosen samples from the generated data as real, fake, or unsure. Results demonstrate that images generated with the diffusion model can translate characteristics that are otherwise very specific to certain medical conditions in chest X-Ray or CT images. Careful tuning of the model can be very promising. To the best of our knowledge, this is the first attempt to generate lungs X-Ray and CT images using neural diffusion models. This work aims to introduce a new dimension in artificial intelligence for medical imaging. Given that this is a new topic, the paper will serve as an introduction and motivation for the research community to explore the potential of diffusion models for medical image synthesis. We have released the synthetic images on https://www.kaggle.com/datasets/hazrat/awesomelungs.

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Rossi, Armando, und Giorgio Rossi. „Diffusion of Malignant Tumors of Intraperitoneal Organs to the Peritoneum, Ligaments, Mesenteries, Omentum and Lymph Nodes“. In CT of the Peritoneum, 353–403. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56488-8_13.

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Kaur, Kavkirat, und Shailendra Tiwari. „Low-Dose CT Image Reconstruction Using Complex Diffusion Regularization“. In Advances in Intelligent Systems and Computing, 657–68. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1135-2_50.

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Manniesing, Rashindra, und Wiro Niessen. „Multiscale Vessel Enhancing Diffusion in CT Angiography Noise Filtering“. In Lecture Notes in Computer Science, 138–49. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/11505730_12.

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Kroon, Dirk-Jan, Cornelis H. Slump und Thomas J. J. Maal. „Optimized Anisotropic Rotational Invariant Diffusion Scheme on Cone-Beam CT“. In Medical Image Computing and Computer-Assisted Intervention – MICCAI 2010, 221–28. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-15711-0_28.

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Wan, Simon. „MRI and Diffusion-Weighted MRI in Treatment Response Evaluation Overview“. In Atlas of Clinical PET-CT in Treatment Response Evaluation in Oncology, 17–26. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-68858-5_3.

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Liu, Jianfei, Shijun Wang, Jianhua Yao, Marius George Linguraru und Ronald M. Summers. „Manifold Diffusion for Exophytic Kidney Lesion Detection on Non-contrast CT Images“. In Advanced Information Systems Engineering, 340–47. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-40811-3_43.

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de Win, Maartje M. L. „Imaging of the Orbit: “Current Concepts”“. In Surgery in and around the Orbit, 121–39. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-40697-3_4.

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AbstractOrbital imaging with CT or MRI can be essential in the evaluation of many orbital conditions. Because of its superior bony characterization and fast acquisition, CT is imaging method of first choice in urgent situations like trauma, infection, and evaluation of lesions arising from the orbital wall. Through recent years, CT has also gained a prominent role in (pre)operative planning and navigation, especially through the development of postprocessing software. For the evaluation of more complex orbital disease, MRI is the preferred modality. With its superior soft-tissue differentiation, MRI is useful for determining the extent of orbital lesions, like inflammatory disease, vascular malformations, and orbital tumors. By adding functional MRI techniques, like diffusion and perfusion-weighted imaging, and by combining parameters of different imaging techniques in multiparametric imaging, it is possible to further improve characterization of orbital lesions. In this chapter, the optimal approach to orbital imaging is described, combining knowledge of orbital imaging techniques and imaging indications, together with a structured way of reviewing the orbital images, knowledge of radiological features of common, and more uncommon orbital pathology, and integrating this with the clinical features of the patient.

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Leiva-Salinas, Carlos, Wade Smith und Max Wintermark. „Application of MR Diffusion, CT Angiography and Perfusion Imaging in Stroke Neurocritical Care“. In Emergency Management in Neurocritical Care, 205–13. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118297162.ch23.

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Konferenzberichte zum Thema "Diffusion CT"

Liu, Anqi, Grace J. Gang und Joseph W. Stayman. „Fourier diffusion for sparse CT reconstruction“. In Physics of Medical Imaging, herausgegeben von Rebecca Fahrig, John M. Sabol und Ke Li. SPIE, 2024. http://dx.doi.org/10.1117/12.3008622.

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Li, Shudong, Matthew Tivnan und Joseph W. Stayman. „Diffusion posterior sampling for nonlinear CT reconstruction“. In Physics of Medical Imaging, herausgegeben von Rebecca Fahrig, John M. Sabol und Ke Li. SPIE, 2024. http://dx.doi.org/10.1117/12.3007693.

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Fogden, Andrew, Terri Olson, Qianhao Cheng, Jill Middleton, Andrew Kingston, Michael Turner, Adrian Sheppard und Ryan Armstrong. „Dynamic Micro-CT Imaging of Diffusion in Unconventionals“. In Unconventional Resources Technology Conference. Society of Petroleum Engineers, 2015. http://dx.doi.org/10.2118/178617-ms.

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Fogden, Andrew, Terri Olson, Michael Turner und Jill Middleton. „Dynamic Micro-CT Imaging of Diffusion in Unconventionals“. In Unconventional Resources Technology Conference. Tulsa, OK, USA: American Association of Petroleum Geologists, 2015. http://dx.doi.org/10.15530/urtec-2015-2154822.

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Gao, Yuan, Huiqiao Xie, Chih-Wei Chang, Junbo Peng, Jing Wang, Lei Qiu, Tonghe Wang et al. „Contrast-enhanced dual-energy CT synthesis from single energy CT using diffusion model“. In Clinical and Biomedical Imaging, herausgegeben von Barjor S. Gimi und Andrzej Krol. SPIE, 2024. http://dx.doi.org/10.1117/12.3008507.

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Douiri, Abdel, Musib Siddique, Xujiong Ye, Gareth Beddoe und Greg Slabaugh. „Enhanced detection in CT colonography using adaptive diffusion filtering“. In SPIE Medical Imaging, herausgegeben von Josien P. W. Pluim und Benoit M. Dawant. SPIE, 2009. http://dx.doi.org/10.1117/12.811563.

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Pan, Shaoyan, Elham Abouei, Jacob Wynne, Tonghe Wang, Richard Qiu, Yuheng Li, Chih-Wei Chang et al. „Synthetic CT generation from MRI using 3D diffusion model“. In Image Processing, herausgegeben von Olivier Colliot und Jhimli Mitra. SPIE, 2024. http://dx.doi.org/10.1117/12.3006578.

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Ferreira, Victor, Anselmo Cardoso de Paiva, Aristofanes Silva, João Sousa de Almeida, Geraldo Braz Junior und Francesco Renna. „Diffusion Model for Generating Synthetic Contrast Enhanced CT from Non-Enhanced Heart Axial CT Images“. In 26th International Conference on Enterprise Information Systems. SCITEPRESS - Science and Technology Publications, 2024. http://dx.doi.org/10.5220/0012724600003690.

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Bruder, H., R. Raupach, E. Klotz, K. Stierstorfer und T. Flohr. „Spatio-temporal filtration of dynamic CT data using diffusion filters“. In SPIE Medical Imaging, herausgegeben von Ehsan Samei und Jiang Hsieh. SPIE, 2009. http://dx.doi.org/10.1117/12.811085.

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Khazaee, Tina, Chris J. D. Norley, Hristo N. Nikolov, Steven I. Pollmann und David W. Holdsworth. „Micro-CT imaging technique to characterize diffusion of small-molecules“. In Biomedical Applications in Molecular, Structural, and Functional Imaging, herausgegeben von Barjor S. Gimi und Andrzej Krol. SPIE, 2020. http://dx.doi.org/10.1117/12.2548624.

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