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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Naoki Kawachi Shu Fujimaki Satomi Ishii Nobuo Suzui Noriko S. Ishioka Shinpei Matsuhashi Plant Positron Imaging Group Quantum Beam Science Directrate Japan Atomic Energy Agency Takasaki Gunma Japan

The positron emitting tracer imaging system (PETIS) and carbon-11-labeled carbon dioxide ( 11 CO 2 ) can image carbon movement during photosynthesis in a plant leaf, and 11 C kinetics make it possible to estimate physiological function parameters in those photosynthesis processes. With an exposure 11 CO 2 gas to a leaf, PETIS experiments were performed iteratively under dark and light environments on a single leaf. In order to estimate the rate constants of photosynthetic parameters, time activity curves of 11 CO 2 gas input and leaf response were fitted to an appropriate compartmental tracer kinetic model, which applies influx and efflux for photo-assimilation and sucrose export rate constants respectively. Results obtained from the kinetic analysis are consistent with physiological knowledge and important to discuss photosynthesis in plant physiology and agriculture. In addition, the proposed method in this paper produce parametric images of photosynthetic functions on a pixel-by-pixel basis successfully, in other words, molecular imaging for plant study is demonstrated.

关键词： Carbon dioxide Positrons Kinetic theory Parameter estimation Sugar Plants (biology) physiology Agriculture Pixel Molecular imaging

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Extracellular matrix (ECM) microstructural composition regulates local cell-ECM biomechanics and fundamental fibroblast behavior: a multidimensional perspective

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JOURNAL OF APPLIED physiology 2005年第5期98卷 1909-1921页

作者： Pizzo, AM Kokini, K Vaughn, LC Waisner, BZ Voytik-Harbin, SL Purdue Univ Sch Vet Med Weldon Sch Biomed Engn Dept Basic Med Sci W Lafayette IN 47907 USA Purdue Univ Sch Vet Med Sch Mech Engn W Lafayette IN 47907 USA Univ Alabama Dept Mech Engn Tuscaloosa AL USA

The extracellular matrix (ECM) provides the principal means by which mechanical information is communicated between tissue and cellular levels of function. These mechanical signals play a central role in controlling cell fate and establishing tissue structure and function. However, little is known regarding the mechanisms by which specific structural and mechanical properties of the ECM influence its interaction with cells, especially within a tissuelike context. This lack of knowledge precludes formulation of biomimetic microenvironments for effective tissue repair and replacement. The present study determined the role of collagen fibril density in regulating local cell-ECM biomechanics and fundamental fibroblast behavior. The model system consisted of fibroblasts seeded within collagen ECMs with controlled microstructure. Confocal microscopy was used to collect multidimensional images of both ECM microstructure and specific cellular characteristics. from these images temporal changes in three-dimensional cell morphology, time- and space-dependent changes in the three-dimensional local strain state of a cell and its ECM, and spatial distribution of beta 1-integrin were quantified. Results showed that fibroblasts grown within high-fibril-density ECMs had decreased length-to-height ratios, increased surface areas, and a greater number of projections. Furthermore, fibroblasts within low-fibril-density ECMs reorganized their ECM to a greater extent, and it appeared that beta 1-integrin localization was related to local strain and ECM remodeling events. Finally, fibroblast proliferation was enhanced in low-fibril-density ECMs. Collectively, these results are significant because they provide new insight into how specific physical properties of a cell's ECM microenvironment contribute to tissue remodeling events in vivo and to the design and engineering of functional tissue replacements.

关键词： three-dimensional local strain fibroblast three-dimensional morphology confocal reflection microscopy incremental digital volume correlation collagen fibril density

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Medical Imaging 2005 physiology, function, and Structure from Medical images

Medical Imaging 2005 Physiology, Function, and Structure fro...

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Medical Imaging 2005 - physiology, function, and Structure from Medical images

The proceedings contain 43 papers from the conference on Medical Imaging 2005 - physiology, function, and Structure from Medical images. The topics discussed include: multimodality assessment of breast tumor physiology and metabolism;nanoengineered multimodal contrast agent for medical image guidance;three-dimensional optical tomographic brain imaging during kainic-acid-induced seizures in rats;perfusion visualization and analysis for pulmonary embolism;an image-based computational model of ovine lung mechanics and ventilation distribution;a numerical study of gas transport in human lung models;relevant information retrieval and fusion of anatomic, physiologic, and metabolic neuroimaging;and three-dimensional coronary angiography.

关键词： Computerized tomography

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Progress in Biomedical Optics and Imaging: Medical Imaging 2005 - physiology, function, and Structure from Medical images - Part 2

Progress in Biomedical Optics and Imaging: Medical Imaging 2...

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Medical Imaging 2005 - physiology, function, and Structure from Medical images

The proceedings contain 46 papers from the conference on Progress in Biomedical Optics and Imaging - Medical Imaging 2005: physiology, function, and Structure from Medical images - Part 2. The topics discussed include: a feasibility study on laxative-free bowel preparation for virtual colonoscopy;CT colonography of the unprepared colon: an evaluation of electronic stool subtraction;ranking of polyp candidates for CAD in CT colonography;assessing breathing motion by shape matching of lung and diaphragm surfaces;estimation of regional lung expansion via 3D image registration;classification of pulmonary airway disease based on mucosal color analysis;and visualization and quantitative analysis of lung microstructure using micro CT images.

关键词： Computerized tomography

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multidimensional segmentation of coronary intravascular ultrasound images using knowledge-based methods

Multidimensional segmentation of coronary intravascular ultr...

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Medical Imaging 2005 conference

作者： Olszewski, ME Wahle, A Vigmostad, SC Sonka, M Univ Iowa Iowa City IA 52242 USA

ISBN: (纸本)0819457213

In vivo studies of the relationships that exist among vascular geometry, plaque morphology, and hemodynamics have recentlv been made possible through the development of a system that accurately reconstructs coronary arteries imaged by x-ray angiography and intravascular ultrasound (IVUS) in three dimensions. Currently, the bottleneck of the system is the segmentation of the IVUS images. It is well known that IVUS images contain numerous artifacts from various sources. Previous attempts to create automated IVUS segmentation systems have suffered from either a cost function that does not include enough information, or from a non-optimal segmentation algorithm. The approach presented in this paper seeks to strengthen both of those weaknesses first by building a robust, knowledge-based cost function, and then by using a fully optimal, three-dimensional segmentation algorithm. The cost function contains three categories of information: a compendium of learned border patterns, information theoretic and statistical properties related to the imaging physics., and local image features. By combining these criteria in an optimal way, weaknesses associated with cost functions that only try to optimize a single criterion are minimized. This cost function is then used as the input to a fully optimal, three-dimensional, graph search-based segmentation algorithm. The resulting system has been validated against a set of manually traced IVUS image sets. Results did not show any bias, with a mean unsigned luminal border positioning error of 0.180 +/- 0.027 mm and an adventitial border positioning error of 0.200 +/- 0.069 mm.

关键词： intravascular ultrasound segmentation

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Visualization and quantitative analysis of lung microstructure using micro CT images

Visualization and quantitative analysis of lung microstructu...

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Medical Imaging 2005 conference

作者： Yamamoto, T Kubo, M Kawata, Y Niki, N Univ Tokushima Dept Opt Sci Tokushima 770 Japan

ISBN: (纸本)0819457205

Micro CT system is developed for lung function analysis at a high resolution of the micrometer order (up to 5 mu m in spatial resolution). This system reveals the lung distal structures such as interlobular septa, terminal bronchiole, respiratory bronchiole, alveolar duct, and alveolus. In order to visualize lung 3-D microstructures using micro CT images and to analyze them, this research presents a computerized approach. This approach is applied for to micro CT images of human lung tissue specimens that were obtained by surgical excision and were kept in the state of the inflated fixed lung. This report states a wall area such as bronchus wall and alveolus wall about the extraction technique by using the surface thinning process to analyze the lung microstructures from micro CT images measured by the new-model micro CT system.

关键词： micro CT lung microstructures pulmonary alveolus surface thinning

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Deformation analysis of Hoffa's fat pad from CT images of knee flexion and extension

Deformation analysis of Hoffa's fat pad from CT images of kn...

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Medical Imaging 2005 conference

作者： Hamarneh, G Chu, V Bordalo-Rodrigues, M Schweitzer, M Simon Fraser Univ Sch Comp Sci Burnaby BC V5A 1S6 Canada

ISBN: (纸本)0819457205

Recent advances in medicine conjecture that certain body fat may have mechanical function in addition to its classical role of energy storage. In particular we aim to analyze if the intra-articular fat pad of Hoffa is merely a space holder or if it changes shape to provide cushioning for the knee bones. Towards this goal, 3D CT images of real knees, as well as a skeletal knee model with fat simulating Hoffa's pad, were acquired in both extension and flexion. Image segmentation was performed to automatically extract the real and simulated fat regions from the extension and flexion images. Utilizing the segmentation results as binary masks, we performed automatic multi-resolution image registration of the fat pad between flexed and extended knee positions. The resulting displacement fields from flexion-extension registration are examined and used to calculate local fat volume changes thus providing insight into shape changes that may have a mechanical component.

关键词： medical image analysis segmentation registration shape deformation local volume change knee flexion extension computed tomography the insight toolkit (ITK)

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Vessel segmentation in retinal images

Vessel segmentation in retinal images

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Medical Imaging 2005 conference

作者： Paulus, D Chastel, S Feldmann, T Univ Koblenz Landau Inst Computervisualistik D-56070 Koblenz Germany

ISBN: (纸本)0819457205

Detection of the papilla region and vessel detection on images of the retina are problems that can be solved with pattern recognition techniques. Topographic images, as provided e.g. by the HRT device, as well as fundus images can be used as source for the detection. It is of diagnostic importance to separate vessels inside the papilla area from those outside this area. Therefore, detection of the papilla is important also for vessel segmentation. In this contribution we present state of the art methods for automatic disk segmentation and compare their results. Vessels detected with matched filters (wavelets, derivatives of the Gaussian, etc.) are shown as well as vessel segmentation using image morphology. We present our own method for vessel segmentation based on a special matched filter followed by image morphology. In this contribution we argue for a new matched filter that is suited for large vessels in HRT images.

关键词： Image segmentation Image filtering Retina Optic nerve Diagnostics Gaussian filters Head Reflectivity Optical discs Tomography

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A comparison of Gaussian based ANNs for the classification of multidimensional hyperspectral signals

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8th Biennial Meeting of the International Work-conference on Artificial Neural Networks

作者： Prieto, A Bellas, F Duro, RJ Lopez-Peña, F Univ A Coruna Grp Sist Autonomos La Coruna Spain

ISBN: (纸本)3540262083

This paper is concerned with the comparison of three types of Gaussian based Artificial Neural Networks in the very high dimensionality classification problems found in hyperspectral signal processing. In particular, they have been compared for the spectral unmixing problem given the fact that the requirements for this type of classification are very different from other realms in two aspects: there are usually very few training samples leading to networks that are very easily overtrained, and these samples are not usually representative in terms of sampling the whole input-output space. The networks selected for comparison go from the classical Radial Basis function (RBF) network to the more complex Gaussian Synapse Based Network (GSBN) considering an intermediate type, the Radial Basis function with Multiple Deviation (RBFMD). The comparisons were carried out when processing a benchmark set of synthetic hyperspectral images containing mixtures of spectra from materials found in the US Geological Service database.

关键词： Neural networks

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Robust segmentation of 4D cardiac MRI-tagged images via spatio-temporal propagation

Robust segmentation of 4D cardiac MRI-tagged images via spat...

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Medical Imaging 2005 conference

作者： Qian, Z Huang, XL Metaxas, D Axel, L Rutgers State Univ CBIM Ctr Computat Biomed Imaging & Modeling Piscataway NJ 08854 USA

ISBN: (纸本)0819457205

In this paper we present a robust method for segmenting and tracking cardiac contours and tags in 4D cardiac MRI tagged images via spatio-temporal propagation. Our method is based on two main techniques: the Metamorphs Segmentation for robust boundary estimation, and the tunable Gabor filter bank for tagging lines enhancement, removal and myocardium tracking. We have developed a prototype system based on the integration of these two techniques, an achieved efficient, robust segmentation and tracking with minimal human interaction.

关键词： tagged MRI metamorphs segmentation Gabor filter bank tracking

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