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Bayesian Registration Of Models Using Fem Eigenmodes
"... Highest Confidence First (HCF) estimation is applied to deterministic scaledordered nonrigid registration of organ models. A local Posterior energy measure is computed from Bayesian combination of local Prior and Likelihood energy measures, over a Markov Random Field (MRF) defined over the Finite E ..."
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Highest Confidence First (HCF) estimation is applied to deterministic scaledordered nonrigid registration of organ models. A local Posterior energy measure is computed from Bayesian combination of local Prior and Likelihood energy measures, over a Markov Random Field (MRF) defined over the Finite Element neighbourhood of every element node. Prior energy is derived from the Gompertz metric of biological growth, and Likelihood energy is derived from the biologically meaningful similarity between local FEM eigenmode displacement components. The Centroid Size metric is generalised to give the characteristic scale of an organ model, which allows for normalisation of model size and eigenmode magnitude. Linear axes along which modal moments act are used as an estimate of intrinsic model pose, so that initial rigidbody registration can be achieved. Contents 1 Introduction 3 1.1 Prospectus : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 3 2 Size metric 5 2.1 Covar...
Issues In 3D FreeHand Medical Ultrasound Imaging
 Dept. of Engineering, University of Cambridge
, 1996
"... A drawback of conventional 2D ultrasound imaging is the requirement that the physician mentally reconstruct 3D anatomy given multiple 2D image slices. This paper reviews attempts to overcome this problem using 3D ultrasonic imaging. It is argued that freehand imaging holds the most promise for ..."
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A drawback of conventional 2D ultrasound imaging is the requirement that the physician mentally reconstruct 3D anatomy given multiple 2D image slices. This paper reviews attempts to overcome this problem using 3D ultrasonic imaging. It is argued that freehand imaging holds the most promise for effective and inexpensive 3D ultrasound. In the freehand paradigm, the physician is allowed to move the probe freely over the region of interest, while a sensing device records the position of each scan. The set of 2D scans and position data are subsequently used to construct a 3D data set which can be rendered on a computer monitor or used for volumetric data analysis. In this paper the strengths and weaknesses of freehand imaging are identified, with reference to sources of error in the measurement, reconstruction, visualisation and volumetric analysis processes. The findings suggest several key research topics, aimed at overcoming some of the limitations of freehand imaging.
A Biological Growth Metric For 3D Shape Registration
, 1995
"... We review the Turing (1952) and OsterMurray (1988) models of biological morphogenesis. From the latter we apply primary mechanisms of extracellularmatrix (ECM) deformation, cell mitosis, cell diffusion and ECMcell interaction to a model of biological growth, and derive the principal modes of mas ..."
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We review the Turing (1952) and OsterMurray (1988) models of biological morphogenesis. From the latter we apply primary mechanisms of extracellularmatrix (ECM) deformation, cell mitosis, cell diffusion and ECMcell interaction to a model of biological growth, and derive the principal modes of mass flux from the linear eigenmodes of each mechanism. The assumption of uniform mass distribution means that the eigenmodes are the same for elastic, diffusive and convective modes. We derive a metric of biological growth using the Gompertz function and show that it can also be arrived at from a thermodynamic model of growth inhibition. This metric is to be used in 3D shape registration, and can be computed for partial local registrations using a linear sum of eigenmode projections. Contents 1 Introduction 3 1.1 Prospectus : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 3 2 Biological morphogenesis 5 2.1 The Turing mechanism : : : : : : : : : : : : : : : : : : :...
ModelBased ThreeDimensional
, 1996
"... at the University of Cambridge Summary A 3D freehand ultrasound system augments a conventional clinical scanner with a position sensor on the handheld probe. Such systems are safe, cheap, portable, and allow clinicians to scan using conventional techniques. Unfortunately the resulting freehand imag ..."
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at the University of Cambridge Summary A 3D freehand ultrasound system augments a conventional clinical scanner with a position sensor on the handheld probe. Such systems are safe, cheap, portable, and allow clinicians to scan using conventional techniques. Unfortunately the resulting freehand images are nonparallel, sometimes selfintersecting, and retain the noisy image artefacts inherent in conventional 2D ultrasound. This dissertation proposes two modelbased strategies for interpreting such images: an organ shape model is used for geometric reconstruction of scattered organ landmarks in the images, and the Gompertz growth model is used to register organ shape models to each other in a coherent and biologically justified way. Both strategies are robust to noise and inaccuracies in the organ model meshes, and are intended to complement future work on the detection of tissue boundaries in ultrasound images. So a modelbased framework to organise sparse and noisy cues about tissue boundaries, is a key element in any attempt at fullyautomated interpretation of 3D freehand ultrasound images. A biological model of organ growth is first developed using OsterMurray mechanisms, whose eigenmodes describe the organ's modes of shape variation. An iterative procedure allows these idealised modes to be refined from organ examples. 3D freehand ultrasound images are then segmented by such organ models, for the purpose of organ volume estimation. However, an organ model can only be refined from the segmented organ shape if they both share a common shape parameterisation.
Matching Image Objects in Dynamic
"... Abstract: The paper presents an approach for matching image objects in dynamic pedobarography image sequences, based on finite element modelling of the objects and on modal analysis of the of the object models. The proposed approach allows the determination of correspondences between two distinct im ..."
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Abstract: The paper presents an approach for matching image objects in dynamic pedobarography image sequences, based on finite element modelling of the objects and on modal analysis of the of the object models. The proposed approach allows the determination of correspondences between two distinct images, using either 2D or 3D modelling. The displacement vectors for the nodes of the matched object models are also determined, based on which the deformation energy is computed. The deformation energy can be used as a global measure of the similarity of the matched objects.