Spelling suggestions: "subject:"image processing computer - assisted"" "subject:"lmage processing computer - assisted""
11 |
The reliability of three-dimensional computer-generated linear and angular cephalometric measurementsKusnoto, Budi. January 1998 (has links)
Thesis (M.S. in oral sciences)--University of Illinois at Chicago, 1998. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
|
12 |
An assessment of facial profile preference of surgical patients using video imagingArpino, Vincent J. January 1996 (has links)
Thesis (M.S.)--University of Illinois at Chicago, 1996. / Includes bibliographical references.
|
13 |
Harmonic source wavefront aberration correction for ultrasound imaging.Dianis, SW, von Ramm, OT 01 1900 (has links)
A method is proposed which uses a lower-frequency transmit to create a known harmonic acoustical source in tissue suitable for wavefront correction without a priori assumptions of the target or requiring a transponder. The measurement and imaging steps of this method were implemented on the Duke phased array system with a two-dimensional (2-D) array. The method was tested with multiple electronic aberrators [0.39π to 1.16π radians root-mean-square (rms) at 4.17 MHz] and with a physical aberrator 0.17π radians rms at 4.17 MHz) in a variety of imaging situations. Corrections were quantified in terms of peak beam amplitude compared to the unaberrated case, with restoration between 0.6 and 36.6 dB of peak amplitude with a single correction. Standard phantom images before and after correction were obtained and showed both visible improvement and 14 dB contrast improvement after correction. This method, when combined with previous phase correction methods, may be an important step that leads to improved clinical images. / Dissertation
|
14 |
Inverse problems in transcient [sic] elastography. / Inverse problems in transient elastographyJanuary 2012 (has links)
由線性彈性模型引起的多維系數反問題在很多範疇都有其應用,如斷層探測、油田檢測、鹽石檢測、礦石檢測及醫療成像等。瞬時成像技術是其中最有用的應用。它提供了一個快速及安全的醫療成像技術,可以用來檢測在身體內快速移動的器官的一些異常組織,如肝腫瘤。在這篇論文中,我們會重點討論兩個解決瞬時弹性成像反問題的數值方法,即水平集反演方法和近似全局收斂方法。我們會研究這兩種方法的推導和數值結果。 / 特別地,近似全局收斂方法是一種由Klibanov 新提出用來解決由雙曲偏微分引起的多維系數反問題的方法。因為這佪方法沒有使用求泛函極小值的步驟,因此能避免了一些眾所周知的問題,所以它特別穩定。數值結果顯示近似全局收斂方法對噪聲有很高的穩定性。這表明近似全局收斂方法是一個解決由線性彈性模型引起的多維系數反問題的其中一個有效方法。 / Multi-dimensional coefficient inverse problem (MCIP) in linear elasticity has found many applications, such as crack detection, oil/salt/ore detection, medical imaging. Transient elastography is among one of the most useful applications, providing a fast and safe medical imaging technique which can be used to detect tumors or abnormal tissue in “fast-moving“ organs such as the liver. In this thesis focus is casted on two of the numerical algorithms to solve inverse problems related to transient elastography, namely the level-set inversion method and the approximate globally convergent method. The derivations of both methods and numerical results are presented. In particular, the approximate globally convergent method is a newly developed stable method to solve coefficient determination inverse problem for hyperbolic partial differential equation proposed by Beilina and Klibanov in [6]. It achieves pproximately a global convergence by avoiding construction of a least squares functional, thus averting some of the well-known problems of trapping in the neighborhoods of local minima when one minimizes such a nonlinear functional. The results of the approximate globally convergent method have shown its strong stability and robustness. This suggests a good way for the reconstruction of the distribution of the shear modulus in the coefficient inverse problem of linear elasticity. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chow, Yat Tin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 98-102). / Abstracts also in Chinese. / Chapter 1 --- Introduction --- p.6 / Chapter 2 --- Linear Elasticity Model --- p.9 / Chapter 2.1 --- Introduction to Linear Elasticity Model --- p.9 / Chapter 2.2 --- Physical Meanings of Elasticity Equation --- p.12 / Chapter 2.3 --- Derivations of Linear Elasticity Equation --- p.14 / Chapter 2.4 --- Discussion of Christoffel’s Equation --- p.17 / Chapter 3 --- Formulations of the Forward and Inverse Problem --- p.27 / Chapter 3.1 --- The Forward Problem --- p.29 / Chapter 3.2 --- The Inverse Problem --- p.29 / Chapter 3.3 --- A Uniqueness Result --- p.30 / Chapter 4 --- Algorithms for Inverse Problems in Elasticity --- p.33 / Chapter 5 --- Level Set Inversion Method --- p.37 / Chapter 5.1 --- Arrival Time Acquisition: Cross-Correlation --- p.37 / Chapter 5.2 --- The Distance Inversion Method --- p.41 / Chapter 5.3 --- Solving the Forward Eikonal Equation --- p.43 / Chapter 5.3.1 --- Discretizing the eikonal equation --- p.43 / Chapter 5.3.2 --- A forward eikonal solver: fast marching algorithm --- p.47 / Chapter 5.3.3 --- A forward eikonal solver: fast sweeping algorithm --- p.50 / Chapter 5.4 --- Level Set Inversion Scheme --- p.54 / Chapter 5.5 --- Numerical Implementation --- p.57 / Chapter 5.6 --- Results of Reconstructions --- p.58 / Chapter 6 --- Approximate Globally Convergent Method --- p.63 / Chapter 6.1 --- The Forward Problem --- p.65 / Chapter 6.1.1 --- Forward problem in time domain --- p.65 / Chapter 6.1.2 --- Forward problem in Laplace domain --- p.67 / Chapter 6.2 --- The Inverse Problem --- p.67 / Chapter 6.2.1 --- Inverse problem in time domain --- p.67 / Chapter 6.2.2 --- Inverse problem in Laplace domain --- p.68 / Chapter 6.3 --- A Nonlinear Integral Differential Equation --- p.69 / Chapter 6.4 --- Approximation of the First Tail --- p.71 / Chapter 6.5 --- The Algorithm --- p.72 / Chapter 6.6 --- Notes About the Convergence Analysis --- p.76 / Chapter 6.6.1 --- Approximate global convergence --- p.76 / Chapter 6.6.2 --- Basic formulation of Theorem 2.9.4 of [6] --- p.78 / Chapter 6.6.3 --- Some ideas of the convergence analysis for the algorithm in section 6.5 --- p.80 / Chapter 6.7 --- Numerical Implementation --- p.81 / Chapter 6.8 --- Results of Reconstructions --- p.88 / Chapter 7 --- Conclusions --- p.96 / Bibliography --- p.98
|
15 |
Multiscale geodesic active contours and local phase information in ultrasonic applications: 多尺度測地主動輪廓線和局部相位信息在超聲應用中的使用. / 多尺度測地主動輪廓線和局部相位信息在超聲應用中的使用 / Multiscale geodesic active contours and local phase information in ultrasonic applications: Duo chi du ce di zhu dong lun kuo xian he ju bu xiang wei xin xi zai chao sheng ying yong zhong de shi yong. / Duo chi du ce di zhu dong lun kuo xian he ju bu xiang wei xin xi zai chao sheng ying yong zhong de shi yongJanuary 2014 (has links)
在各种临床应用广泛使用的诊断和治疗工具中,超声成像是其中的一个。与其他成像模式相比,比如计算机断层照相法和磁共振成像,超声波检查法有许多优点:没有辐射风险,设备价格低以及能够实时获取图像。很多超声应用的第一步通常是对感兴趣组织和结构的检测和定位。然而,超声图像存在一些特有的伪影,比如高噪声,低信噪比和灰度不均,这些伪影使得检测任务变得困难。此外,感兴趣区域之间的低对比度也使得这一任务变得更加复杂。在这篇论文里,我们深入研究这些图像伪影并提出新的方法来促进临床中的超声应用。 / 首先,我们提出一个多尺度的框架来进行超声图像的分割,这个框架是基于各向异性去噪扩散和测地主动轮廓线的。各向异性去噪扩散是对边缘敏感且专门用于斑点噪声图像的扩散过程,这里它被用来去除超声图像的斑点噪声,我们对每幅输入图像构造一个多尺度的表示方法,随着尺度的增加,噪声被逐渐地消除。之后,多尺度测地主动轮廓线从粗到细渐进地应用到这些尺度来提取物体的边界线。为了避免在低对比度区域出现边界泄漏的情况,我们把不同尺度之间的边界形状相似性结合到传统的测地主动轮廓线模型里作为一个外部约束来指导轮廓线的演化。在合成和临床图像的实验结果证明了我们的方法的优越性。 / 其次,我们提出一个基于相位的方法来检查和测量超声图像里的胎儿腹部轮廓线。我们定义了一个基于局部相位的度量来检测胎儿腹部的边界线,这个度量称为多尺度特征非对称性,它与图像的亮度无关,并且能为图像里特征的重要程度提供一个绝对的测量。为了估计与腹部轮廓线相吻合的椭圆,我们使用一个迭代随机霍夫变换来排除内腹部边界线的影响,从而使得估计的椭圆逐渐收敛到外边界线。在临床超声图像里进行腹部周长测量的实验结果验证了我们的方法与手工的方法有很高的一致性,这也表明我们的方法可以作为一个可靠的工具来进行产科的护理和诊断。 / Ultrasound imaging is one of the most widely used diagnostic and therapeutic tools for a variety of clinical applications. Compared with other imaging modalities, such as computed tomography and magnetic resonance imaging, ultrasonography has a lot of advantages: free of radiation risk, low cost of acquisition and images are available in real-time. The first step in many ultrasonic applications is usually the detection and localization of interested tissues and structures. However, there are a number of characteristic artifacts in ultrasound images that make the task difficult such as high speckle noise, low signal-to-noise ratio and intensity inhomogeneity. Besides, the low contrast between regions of interest further complicates the processing. In this thesis, we deeply investigate these image artifacts and propose new techniques to facilitate ultrasonic applications in clinic. / First, we propose a multiscale framework for ultrasound image segmentation based on speckle reducing anisotropic diffusion(SRAD) and geodesic active contours (GAC). SRAD is an edge-sensitive diffusion tailored for speckled images, and it is adopted here to reduce speckle noise by constructing a multiscale representation for each input image, where the noise is gradually removed as the scale increases. Multiscale geodesic active contours are then applied along the scales in a coarse-to-fine manner to capture the object boundaries progressively. To avoid boundary leakages in low contrast regions, traditional GAC model is modified by incorporating the boundary shape similarity between different scales as an external constraint to guide the contour evolution. Experimental results in both synthetic and clinical images demonstrate the superiority of the proposed approach. / Second, we propose a phase-based approach for fetal abdominal contour detection and measurement in ultrasound images.We define a local phase-based measure, called multiscale feature asymmetry (MSFA), from the monogenic signal to detect the boundaries of fetal abdomen. The MSFA measure is intensity invariant and provides an absolute measurement for the significance of features in the image. In order to estimate the ellipse that fits to the abdominal contour, we employ an iterative randomized Hough transform to exclude the interferences of the inner boundaries of the abdomen, after which the estimated ellipse gradually converges to the outer boundaries. Experimental results in clinical ultrasound images validate the high agreement between our approach and manual approach in the measurement of abdominal circumference, indicating that the proposed approach can be used as a reliable tool for obstetric care and diagnosis. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wang, Weiming . / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 68-84). / Abstracts also in Chinese. / Wang, Weiming .
|
16 |
Image analysis of retinal vascular network geometry and its relationship to cardiovascular complications. / 圖像分析視網膜血管網的特徵及其與心血管疾病的關係 / CUHK electronic theses & dissertations collection / Tu xiang fen xi shi wang mo xue guan wang de te zheng ji qi yu xin xue guan ji bing de guan xiJanuary 2012 (has links)
目的1)發現與中風相闋的視網膜特徵2) 利用視網膜特徵建立統計模型對老年人中風風險進行分類。 / 方法:配對病例對照研究。病例為中風患者,一部分中風患者來自於糖尿病眼病的篩查項目,另外一部分是腦內科的中風患者。對照是沒有中風的老年人。對照來自糖尿病眼病篩查項目內沒有患中風的患者及在眼科門診沒有中風及特殊眼病的患者。對照與病例在年齡及是否患有糖尿病進行匹配。所有研究對象均來自香港威爾斯親王醫院。我們收集所有研究對象的中風危險因素,包括年齡,性別,吸煙,及是否患有糖尿病,高血壓,缺血性心髒病,心房顫動,高血脂。所有研究對象的彩色視網膜照片都被採集。我們應用軟件“ImageJ"分析並記錄視網膜動靜脈直徑,血管分叉係數,分叉角度,分叉對稱性,視乳頭周長。我們也記錄其他視網膜特徵,如動靜脈壓跡,出血,硬性滲出,動脈阻塞及血管彎曲性。獨立t檢驗用於對連續變量的單因素分析,卡方檢驗用於對分類變量的單因素分析。Logistic 回歸用於建立統計模型對中風風險進行分類。所有統計方法均應用SPSS16.0 軟件。 / 結果:本研究納入122 中風患者及122 例患者做對照。每組分別有81 例糖尿病患者, 41 例非糖尿病患者。視網膜特徵包括動靜脈直徑,血管彎曲度,出血,硬性滲出,動靜脈壓跡在兩組中有顯著性差異。我們建立風險模型對兩組患者進行風險分類。分類準確度最高達的模型裡面包括的因子有:1)中風相關危險因素包括:高血壓,糖尿病,心房顫動2) 視網膜特徵包括:動脈直徑,血管彎曲性,出血,動靜脈壓跡跟靜脈對稱性;3) 視網膜特徵間的交立作用包括:動脈直徑與靜脈對稱性,動脈直徑與出血,靜脈對稱性與血管彎曲度。分類的準確度為80 .4%。只包括視網膜特徵的分類模型的準確度為74.5% 。 / 結論:彩色視網膜照相可成為中風風險的分類工具。與中風相關的視網膜特徵包括血管直徑,血管彎曲度,血管對稱性,出血,動靜脈壓跡。視網膜特徵與中風之間的聯繫存在交互作用。 / Objective: 1) To detect retina characteristics that associated with stroke; 2) To develop a statistics model with variables of retina characteristics for classifying patients with stroke from those without stroke in aged population. / Method: Matched case control study. Patients with stroke from the diabetic retinopathy screening program and stroke patients from Acute Stroke Unit were selected as stroke cases. Controls (patients without history of stroke) with matched diabetes status and age were selected from the diabetic retinopathy screening program and eye outpatient clinics. All subjects in this study were from Prince of Wales Hospital, Hong Kong. Risk factors of stroke from all subjects were collected, including age, gender, diabetes, hypertension, hyperlipidemia, history of ischemic heart disease, atrial fibrillation and smoking. Color retina images of each subject were collected and analyzed. The retina characteristics, including diameters of arterioles and venules, bifurcation coefficients, bifurcation angles, branch symmetry, optic disc perimeter were extracted from the color retina images by software "ImageJ". Other retina characteristics including arteriole-venule nicking, hemorrhages, exudates, arteriole occlusion, and vessel tortuosity were also recorded. Independent t test and Chi-squire test were used to compare the continuous and categorical retina characteristics respectively between patients with stroke and those without stroke. Logistic model combining the risk factors of stroke and retina characteristics was established to classify patients with stroke from those without stroke. All data analysis was by SPSS 16.0. / Results: there were 122 stroke cases and 122 controls recruited in this study. There were 41 patients without diabetes and 81 patients with diabetes in each group. Retina characteristics including diameters of arterioles and venules, vessel tortuosity, hemorrhages, exudates, arteriole-venule nicking were significantly different between the two groups. We established risk models to classify patients with stroke from those without stroke. The risk model with highest accuracy of classification included 1) stroke risk factors including hypertension, diabetes and atrial fibrillation; 2) retina characteristics, including arteriole diameters, vessel tortuosity, hemorrhages, arteriolevenule nicking and venule symmetry; 3)interaction between retina characteristics, including arteriole diameters by venule symmetry, arteriole diameters by hemorrhage,and venule symmetry by vessel tortuosity. The accuracy of classification was 80.4%. Using retinal characteristics alone achieved an accuracy of 74.5%. / Conclusion: color retina images are a potential tool for stroke risk stratification. Useful characteristics found in the retinal images included vessel diameters, vessel tortuosity, vessel symmetry, hemorrhage, arteriole-venule nicking. The association between the retinal characteristic and stroke was modified by other retinal characteristics. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Li, Qing. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 139-148). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract (English) --- p.i / Abstract (Chinese) --- p.iii / Acknoledgements --- p.v / Chapter Chapter 1 --- Introduction and review of the Literature --- p.1 / Chapter Section 1: --- Stroke prevention and risk assessment tools --- p.1 / Chapter Section 2: --- Rationale of relationship of vascular circulation between retina and brain --- p.9 / Chapter Section 3: --- Manifestation of hypertensive retinopathy and diabetic retinopathy --- p.12 / Chapter Section 4: --- Retina characteristics related to stroke --- p.15 / Chapter Section 5: --- How to make retina as a tool of risk stratification for stroke --- p.28 / Chapter Section 6: --- Rationale to do study to further explore the useful information in color retina images to make it as tool for stroke risk stratification --- p.31 / Chapter Chapter 2 --- Research hypothesis and general design --- p.33 / Chapter Chapter 3 --- Methods of retia characteristics extraction --- p.34 / Chapter Chapter 4 --- A Study of the Reliability of manual measurement of Retinal characteristics using ImageJ --- p.46 / Chapter Chapter 5 --- A study of comparison of retina characteristics between patients with stroke and patients without stroke --- p.55 / Chapter Section 1: --- Method --- p.56 / Chapter Section 2: --- Result-univariate analysis --- p.62 / Chapter Section 3: --- Results-stratification analysis --- p.68 / Chapter Section 4: --- Result-risk model building for stroke risk stratification --- p.79 / Chapter Chapter 6: --- Discussion --- p.118 / Chapter Chapter 7: --- Limitation of this study --- p.133 / Chapter Chapter 8: --- Future development and application of the study results --- p.134 / Appendix --- p.136 / Reference --- p.139
|
17 |
Análise por meio de elementos finitos de placas de reconstrução em defeitos mandibulares /Macedo, Diogo de Vasconcelos January 2019 (has links)
Orientador: Marcelo Silva Monnazzi / Resumo: Defeitos segmentares no osso mandibular podem ocorrer após traumatismo local, infecção ou ressecção cirúrgica. Não realizar reconstrução nesses pacientes pode acarretar em prejuízo estético grave, dificuldades na mastigação, fala e consequente diminuição de qualidade de vida. Várias possibilidades reconstrutivas estão disponíveis atualmente, e a estabilização temporária dos segmentos ósseos com placas de reconstrução é comumente utilizada quando a reconstrução óssea imediata não é possível. No entanto, pouca atenção tem sido dada aos aspectos biomecânicos envolvidos neste tipo de abordagem e estudos realizados com biomodelos esbarram na dificuldade de simular as forças musculares envolvidas. A utilização da Análise de Elementos Finitos permite avaliar matematicamente estruturas em um ambiente controlado, e a aplicação de forças em qualquer ponto e/ou direção, aferindo a deformação dos materiais, bem como a tensão aplicada aos mesmos. Assim, o objetivo deste estudo foi avaliar placas de reconstrução utilizadas sobre defeitos segmentares, por meio de análise matemática por meio de elementos finitos. Após simulação, foram encontrados menores valores de estresse nas placas de maior espessura, sugerindo maior resistência destas à fratura. Em contrapartida, valores significativamente aumentados de estresse sobre os parafusos estavam presentes nas placas mais espessas. / Abstract: Segmental defects in the mandibular bone may occur after local trauma, infection or surgical resection. Failure to perform reconstruction in these patients can lead to severe aesthetic impairment, difficulties in chewing, speech, and subsequent decrease in quality of life. Numerous reconstructive possibilities are currently available, and the temporary stabilization of bone segments with reconstruction plates is commonly used when immediate bone reconstruction is not possible. However, little attention has been given to the biomechanical aspects involved in this kind of approach and studies carried out with plastic models can not properly reproduce the muscular forces involved. The use of finite element analysis allows to mathematically evaluate structures in a controlled environment and the application of forces at any point and / or direction, assessing the deformation of the materials, as well as the stress applied to them. Thus, the objective of this study is to evaluate reconstruction plates used on segmental defects through mathematical analysis using finite elements. After simulation, lower stress values were found in the thicker plates, suggesting greater resistance to fracture. In contrast, significantly increased stress values on the screws were present on the thicker plates. / Mestre
|
18 |
Image segmentation using prior information and its application on medical ultrasound image processing. / CUHK electronic theses & dissertations collectionJanuary 2004 (has links)
Xie Jun. / "July 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 177-204). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
|
19 |
Variational and spline based multi-modal non-rigid medical image registration and applications. / CUHK electronic theses & dissertations collectionJanuary 2005 (has links)
In the brain mapping case, the geodesic closest points are used as the anatomical constraints for the inter-subject non-rigid registration. The method uses the anatomical constraint in the non-rigid registration which is much more reasonable for the anatomical correspondence. The registration result shows significant improvement comparing with the iterative closest points based method. / In the third application, we use the non-rigid registration method to register the different sweeps of freehand ultrasound images. We setup a 3D freehand ultrasound imaging system to capture images of a human anatomy such as liver, prostate, brain tumor and fetus. The arbitrary scanned image slices are reconstructed and resliced into volumetric dataset. We use a B-spline based non-rigid registration method to compounding different freehand ultrasound sweeps. This technique can be used to make 3D ultrasound models of fetus and other organs. / Medical image registration is an active research area during the last two decades. The registration technique can be widely used in the applications of the computer aided surgery, brain mapping and pathological detection and analysis. With the development of the computing power, fast and accurate registration techniques have been developed into necessary tools for quantitative analysis of the medical image. / Non-rigid registration methods can be used in atlas based image segmentation, inter-subject brain image registration and 3D freehand ultrasound modeling. In one of our proposed novel segmentation methods, we interleave the segmentation and the registration processes by using the segmentation to provide the anatomical constraints for registration to improve the atlas based non-rigid registration. This updated registration can be used to improve the new segmentation. This process is repeated until a good result in segmentation is obtained. / The registration methods can be classified into rigid and non-rigid registrations according to whether the anatomy is locally deformed or not. According to the sensor by which the images are taken, the registration will be divided into mono-modal and multi-modal image registration. Since the invention of the medical imaging devices, great diversity of medical imaging sensors have been developed with different physical principles. In practice we have to face the problem of multi-modal registration. In medical image analysis, we often have to consider the images of the human anatomy with deformable characteristics. In order to achieve this goal we need to use the voxel based registration method which considers all of the voxel information of the images in matching. There are several non-rigid registration approaches. However, the variational approach of non-rigid registration can represent the registration problem into a well-posed problem with a well-founded mathematical base. In our work, we considered the forward and backward deformation functions and proposed a variational approach for a new consistent multi-modal non-rigid registration method. By this way, we will find the forward and backward transform to be close to the inverse of each other. This makes the correspondence between two images more consistent and accurate. We use both explicit and implicit difference method to solve the Euler-Lagrange equation and the results show significant improvements in the transformation inverse consistency. Although variational approach for multi-modal non-rigid registration can solve the non-rigid registration problem well, generally speaking, it is slow. The displacement of each voxel has to be calculated and the iteration time is very long since the number of the unknowns are large. Although a multi-resolution strategy can be used to speed up, the registration problem is still slow when registering large medical datasets. The 3D B-spline based method has been used as an efficient method to register medical images since only a small number of control points are used to manipulate the local deformation field. In our work, we developed a 3D B-spline based consistent multi-modal non-rigid registration method with an explicit representation of derivatives. The conventional optimization methods can be used to find the optimal parameters. We use a hierarchical B-spline refinement method to approximate the deformation function from larger to smaller scale. Since the derivatives of the cost function is represented in an explicit way, the computing is reduced. It is more efficient than directly computing the derivative of the cost function by using a numerical evaluation method. The method can be considered as a multi-grid method for solving the consistent variational registration problem. The computing speed is increased by several times. The B-spline based method needs far less iterations to converge as its number of unknowns is small. / Zhang Zhijun. / "October 2005." / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6645. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 209-233). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
|
20 |
Efeitos da mitomicina-c tÃpica em queimadura de camundongos / Effects of topical mitomycin-c in thermal burns of miceJose Lima de Carvalho Rocha 26 February 2009 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Atualmente, grande parte das investigaÃÃes sÃo dirigidas para a anÃlise de mediadores da resposta imuno-inflamatÃria local e sistÃmica apÃs a agressÃo tÃrmica. A Mitomicina-C (MMC), um antibiÃtico isolado do Streptomyces caespitosus, à utilizado clinicamente para diminuir o processo de cicatrizaÃÃo de feridas, devido a sua aÃÃo antiproliferativa em fibroblastos in vitro. Produziram-se queimaduras dÃrmicas em quarenta e oito camundongos Swiss albino utilizando-se um ferro de solda modificado, aplicado à pele por nove segundos. No primeiro dia (DO) a queimadura foi submetida a tratamento tÃpico, em dose Ãnica, com SF 0,9% (controle) ou Mitomicina-C (MMC). Avaliaram-se os efeitos da MMC na cicatrizaÃÃo de queimaduras utilizando-se mÃtodos macroscÃpicos, microscÃpicos e computacionais no 4 dia (D4), 7o (D7), 14o (D14) e 21o pÃs-queimadura (D21PQ). Na anÃlise macroscÃpica, utilizou-se escala visual analÃgica (EVA), e planimetria digital; nas microscÃpicas, as amostras de pele foram coradas pela picrosirius red (PR) analisadas à microscopia de luz polarizada, quantificando-se a densidade do colÃgeno tipo I e tipo III. Os parÃmetros biomÃtricos nÃo evidenciaram efeitos deletÃrios sobre o estado nutricional dos animais. A EVA demonstrou que as feridas do grupo MMC exibiram melhor aparÃncia significativa que as do grupo controle no D14PQ com p= 0,0002. A taxa mÃdia de migraÃÃo das margens das feridas (TMM) evidenciou menor valor no grupo MMC, sendo diferenÃa bastante significativa (p =0, 0033). A morfometria do processamento de imagem assistida por computador evidenciou que o colÃgeno tipo I teve um comportamento decrescente de deposiÃÃo no grupo controle; jà no grupo tratado com MMC, foi crescente entre D4 e D14, decrescendo entre D14 e D21. Da mesma forma constatou-se uma diferenÃa significante entre os grupos no D14 e bastante significante no D21 na quantidade de colÃgeno tipo III das feridas do grupo MMC, o que evidencia a capacidade da MMC de retardar a transformaÃÃo do colÃgeno imaturo (tipo III) em maturo (tipo I). A MMC foi eficaz em retardar a maturaÃÃo da ferida por queimadura tÃrmica, gerando menor quantidade de fibrose. / Many research works which are currently being carried out are driven towards the analysis of the mediators of the local and systematical immune inflammatory response after episodes of thermal aggression. Mitomycin-C (MMC), an insulated antibiotic of the Streptomyces caespitosus kind is used clinically in order to shorten the wound healing process due to its anti-proliferation action in fibroblasts in vitro. Dermal burns were produced on forty eight Swiss albine mice as a result of using an adapted iron-welding device which inflicted burns upon the back dorsum of the cavies for a lapse of time of nine seconds. On the first day the burns received topical treatment in a single dose with 0.9% sterile isotonic saline (control) or Mitomycin-C (MMC). The effects of MMC in the healing process of the burns were evaluated by using macroscopic, microscopic and computerized methods on the 4th day (PBD 4), 7th (PBD 7), 14th (PBD 14) and on the 21st post-burn day (PBD 21). For the macroscopic analysis an analogical visual scale (AVS) and a digital planimetry were used. On the microscopic analysis, the samples of the skin were colored by picrosirius red (PR) and analyzed at a microscope under a polarized light and the quantification of the collagen type I and III was carried out. The biometric parameters did not evidence any harmful effects over the nutritional conditions of the animals. The AVS evidenced that the wounds of the MMC group presented a significant better look than those of the control group in the PBD 14 (p= 0.0002). The wound edge migration rates (WEMR) evidenced a smaller rate in the MMC group than those of the control group, with significant difference (p =0.0033). The morphometry of the image processing, computer-assisted showed that the collagen type I presented a decreasing behavior in the process of healing in the control group, whereas in the group which was treated with MMC there was growth between PBD 4 and PBD 14 and a decrease between PBD 14 and PBD 21.Likewise, there was a significant difference among the groups on PBD 14 and a quite significant difference on PBD 21 in the amount of collagen type III on the wounds of the MMC, which evidences the capacity of MMC in slowing down the transformation of the immature collagen (type III) into a mature one (type I). MMC has proved to be efficacious in slowing the maturation of the wounds caused by thermal burns, thus generating a minor amount of fibrosis.
|
Page generated in 0.1092 seconds