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SABRE: A time efficient semi-automated regional parcellation method for structural magnetic resonance brain images

6th international conference on medical Imaging computing and computer-assisted intervention

作者： Dade, LA Gao, FQ Kovacevic, N Roy, P Rockel, C O' Toole, CM Quddus, A Feinstein, A Levine, B Black, SE Baycrest Geriatr Care Rotman Res Inst Toronto ON M4S 1V5 Canada Univ Toronto Hlth Sci Ctr Sunnybrook & Womens Coll Toronto ON M4N 3M5 Canada

ISBN: (纸本)3540204644

Structural MR brain imaging is important in the understanding of regional brain changes in healthy aging and in disease processes. Current methods are often labour-intensive, requiring hours of manual tracing. SABRE (Semi-automatic Brain Region Extraction) is a new technique that allows rapid and reliable parcellation of cortical and subcortical brain regions. Utilization of SABRE in conjunction with a validated tissue-compartment segmentation program [1] can provide measures of gray matter, white matter, ventricular CSF, and sulcal CSF measures for designated brain regions. We present data showing high inter-rater reliably for all regions, with correlations between 0.95 - 0.99. Regional tissue measures of healthy young and healthy older adults were also examined, demonstrating the sensitivity of this protocol to brain volume changes that occur with aging.

关键词： Magnetic resonance imaging

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Application of an intra-operative load measuring system for knee replacement surgery

Application of an intra-operative load measuring system for ...

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6th international conference on medical image computing and computer-assisted intervention

作者： Skrinskas, TV Viskontas, DG Ferreira, L Chess, DG Johnson, JA St Josephs Hlth Care London Hand & Upper Limb Ctr Bioengn Lab London ON N6A 4L6 Canada Univ Western Ontario Dept Biomed Engn London ON N6A 3K7 Canada Univ Western Ontario Dept Surg London ON N6A 3K7 Canada Univ Western Ontario Dept Mech & Mat Engn London ON N6A 3K7 Canada

ISBN: (纸本)3540204628

Joint gap balancing during total knee arthroplasty has been an empirical undertaking to date. Ligament tensioning devices exist to aid soft tissue management, however quantifying tension remains problematic. The purpose of this study was to validate modifications made to a current balancing system, allowing for quantification of joint load using a computer-assisted technique. An additional goal was to determine if the tool would improve joint gap management and consequently load balance in an in-vitro model. The load sensing capability of the tool was validated under known loading conditions. Intraoperative use of the tool relative to current techniques was evaluated in a preliminary in-vitro study using cadaveric knees. There was a trend towards improved joint gap management when using the tensioning device, but this did not translate into a more balanced joint in our knee simulator.

关键词： Transplantation (surgical)

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A rapid method for magnetic tracker calibration using a magneto-optic hybrid tracker 1

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6th international conference on medical Imaging computing and computer-assisted intervention

作者： Nakada, K Nakamoto, M Sato, Y Konishi, K Hashizume, M Tamura, S Osaka Univ Div Interdisciplinary Image Anal Suita Osaka 5650871 Japan Kyushu Univ Grad Sch Med Sci Fukuoka 812 Japan

ISBN: (数字)9783540399032

ISBN: (纸本)3540204644

Electromagnetic trackers are greatly affected by magnetic field distortion resulting from metal objects and electronic equipment in close proximity. In this paper, we propose a rapid method for magnetic tracker calibration using a magneto-optic hybrid tracker. Although the calibration data can be acquired by freehand using the hybrid tracker, two problems arise as a result of freehand acquisition. One is the error caused by the time delay between the measurements of optical and magnetic trackers. The other is the inconsistency of calibration accuracy resulting from variations on uniformity and density of the freehand acquisition of calibration data. To overcome the problem of error, we developed a temporal calibration procedure to estimate the time delay and apply it accordingly. For the problem of inconsistent calibration accuracy, we formulated a distortion model selection method using a cross-validation technique with five distortion models obtained by 0-th to 4-th degree polynomial fitting to the calibration data. We experimentally evaluated the method in a setting affected by an actual operating table. By combining the temporal calibration and model selection methods, the error caused by the magnetic distortion was reduced from around 40 mm to less than 2 mm, and 30 seconds were needed to obtain the calibration data for a 200 x 200 x 20 mm(3) volume.

关键词： Errors

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ImLib3D: An efficient, open source, medical image processing framework in C++ 1

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medical image computing and computer-assisted intervention, MICCAI 2003 - 6th international conference Proceedings

作者： Bosc, Marcel Vik, Torbjorn Armspach, Jean-Paul Heitz, Fabrice LSIIT UMR-7005 CNRS Strasbourg I University 67400 Illkirch France IPB UMR-7004 CNRS Strasbourg I University 67085 Strasbourg France

ISBN: (数字)9783540399032

ISBN: (纸本)9783540204640

ImLib3D is a C++ library for 3D medical image processing research. It provides a carefully designed, object-oriented, standards conforming C++ library, as well as a separate visualization system. Focus has been put on simplicity for the researcher who is considered to be the end-user. Source code is freely available and has been placed in an open collaborative development environment.

关键词： image processing

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Accuracy of a fluoroscopy technique for assessing patellar tracking

Accuracy of a fluoroscopy technique for assessing patellar t...

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6th international conference on medical image computing and computer-assisted intervention

作者： Tang, TSY MacIntyre, NJ Gill, HS Fellows, RA Hill, NA Wilson, DR Ellis, RE Queens Univ Sch Comp Kingston ON K7L 3N6 Canada Queens Univ Human Mobil Res Ctr Dept Mech Engn Kingston ON K7L 3N6 Canada Univ Oxford Nuffield Orthopaed Ctr OOEC Nuffield Dept Orthopaed Surg Oxford OX1 2JD England Univ British Columbia Dept Orthopaed Vancouver BC V5Z 1M9 Canada

ISBN: (纸本)3540204628

Accuracy of a novel fluoroscopy-based method of assessing patellar tracking was determined by comparing the pattern of patellar motion with respect to orientation (flexion, internal rotation, and lateral tilt) and translation (lateral, proximal, and anterior) with the pattern of patellar motion measured using Roentgen Stereophotogram-metric Analysis (RSA) in one cadaver knee specimen. Each pose in the patellar motion could be obtained from a single as well as multiple calibrated fluoroscopic images. The mean error (SD) varies from 0.73 (0.44) to 1.60 (0.48) degrees for patellar orientation and from 0.48 (0.37) to 1.20 (0.57) mm. for patellar translation. These errors appear to be sufficiently low to identify clinically significant differences in patellar kinematics.

关键词： Orthopedics

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A fully automatic and robust brain MRI tissue classification method

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medical image ANALYSIS 2003年第4期7卷 513-527页

作者： Cocosco, CA Zijdenbos, AP Evans, AC McGill Univ Montreal Neurol Inst McConnell Brain Imaging Ctr Montreal PQ H3A 2B4 Canada

A novel. fully automatic, adaptive, robust procedure for brain tissue classification from 3D magnetic resonance head images (MRI) is described in this paper. The procedure is adaptive in that it customizes a training set, by using a 'pruning' strategy, such that the classification is robust against anatomical variability and pathology. Starting from a set of samples generated from prior tissue probability maps (a 'model') in a standard, brain-based coordinate system ('stereotaxic space'), the method first reduces the fraction of incorrectly labeled samples in this set by using a minimum spanning tree graph-theoretic approach. Then, the corrected set of samples is used by a supervised kNN classifier for classifying the entire 3D image. The classification procedure is robust against variability in the image quality through a non-parametric implementation: no assumptions are made about the tissue intensity distributions. The performance of this brain tissue classification procedure is demonstrated through quantitative and qualitative validation experiments on both simulated MRI data (10 subjects) and real MRI data (43 subjects). A significant improvement in output quality was observed on subjects who exhibit morphological deviations from the model due to aging and pathology. (C) 2003 Elsevier B.V. All rights reserved.

关键词： automatic brain MRI classification automatic brain tissue segmentation morphological variability insensitivity pruning non-parametric method

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Assessing early brain development in neonates by segmentation of high-resolution 3T MRI 1

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6th international conference on medical Imaging computing and computer-assisted intervention

作者： Gerig, G Prastawa, M Lin, WL Gilmore, J Univ N Carolina Dept Comp Sci Chapel Hill NC 27599 USA Univ N Carolina Dept Psychiat Chapel Hill NC 27599 USA Univ N Carolina Dept Radiol Chapel Hill NC 27599 USA

ISBN: (数字)9783540399032

ISBN: (纸本)3540204644

This paper describes effort towards automatic tissue segmentation in neonatal MRI. Extremely low contrast to noise ratio (CNR), regional intensity changes due to RF coil inhomogeneity and biology, and tissue property changes due to the early myelination and axon pruning processes require a methodology that combines the strength of spatial priors (template atlas), data modelling, and prior knowledge about brain development. We use an EM-type algorithm that includes tissue classification, inhomogeneity correction and brain stripping into an iterative optimization scheme using a mixture distribution model. A statistical brain atlas registered to the subject image serves as a spatial prior. White matter in neonates is modeled as a mixture model of non-myelinated and myelinated regions. A pilot study on 10 neonates demonstrates the feasibility of high-resolution neonatal MRI and of automatic tissue segmentation. Results demonstrate that interleaved segmentation and inhomogeneity correction, guided by a statistical spatial prior, will provide a powerful and efficient segmentation framework for this type of imaging data. It is demonstrated that the mixture model for white matter allows us to segment early myelination regions of the projection tract up to the motor cortex, while also providing Don-myelinated white, gray and csf segmentation. The early myelination regions are hypothesized to develop early but have not yet been shown in quantitative MRI studies.

关键词： Iterative methods

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Tool localization in 3D ultrasound images 1

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medical image computing and computer-assisted intervention, MICCAI 2003 - 6th international conference Proceedings

作者： Novotny, Paul M. Cannon, Jeremy W. Howe, Robert D. Division of Engineering Science Harvard University Cambridge MA United States Department of Cardiac Surgery Children's Hospital Boston MA United States

ISBN: (数字)9783540399032

ISBN: (纸本)9783540204640

The three-dimensional ultrasound imaging, which helps in the visualization of tools during surgical procedures was investigated. The images were acquired with a real-time three-dimensional ultrasound system. The technique was verified by overlaying the three-dimensional ultrasound images with a geometric representation of the cylinder at the calculated position and orientation. The results show that the overlay enhances the image by filling the missing structures.

关键词： medical imaging

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The potential for image guided radiation therapy with cobalt-60 tomotherapy 1

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6th international conference on medical image computing and computer-assisted intervention, MICCAI 2003

作者： Schreiner, L. John Kerr, Andrew Salomons, Greg Dyck, Christine Hajdok, George Medical Physics Department Kingston Regional Cancer Centre 25 King St W KingstonONK7L 5P9 Canada Departments of Physics and Oncology Queen’s University Canada Department of Medical Biophysics University of Western Ontario 790 Commissioners Rd. E LondonONN6A 4L6 Canada

ISBN: (数字)9783540399032

ISBN: (纸本)3540204644

Helical tomotherapy, a new approach for Intensity Modulated Radiation Therapy, employs a fan-beam of radiation from a source mounted in a CT-like ring gantry. Complex conformal dose delivery is achieved by modulating the intensity of the radiation beam as the source revolves about the patient. A particular benefit of helical tomotherapy is the ability to perform in-situ CT imaging to confirm patient set-up, and to reconstruct the dynamically delivered dose distributions. In this paper we present the results of ongoing work to establish the potential for tomotherapy using a Cobalt-60 radioactive source. Both dose delivery and megavoltage CT imaging data confirm the feasibility of image guided radiation therapy using Cobalt-60 tomotherapy. © Springer-Verlag Berlin Heidelberg 2003.

关键词： Radiotherapy

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Temporal lobe epilepsy lateralization based on MR image intensity and registration features

Temporal lobe epilepsy lateralization based on MR image inte...

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6th international conference on medical image computing and computer-assisted intervention

作者： Duchesne, S Bernasconi, N Janke, A Bernasconi, A Collins, DL McGill Univ Montreal Neurol Inst Montreal PQ H3A 2T5 Canada Univ Queensland Ctr Magnet Resonance Brisbane Qld Australia

ISBN: (纸本)3540204628

In the context of MR imaging, explicit segmentation followed by stereologic volumetry of the hippocampus (HC) has been the standard approach toward temporal lobe epilepsy (TLE) lateralization of the seizure focus. The novelty of the method presented here resides in its analysis of characteristics of large, non-specific Volumes of Interest from T1 MRI data aiming to lateralize the seizure focus in patients with TLE without segmentation. For this purpose, Principal Components Analysis (PCA) of two image features are united to create a multi-dimensional space representative of a training set population composed of 150 normal subjects. The feature instances consist of grey-level intensity and an approximation of the Jacobian matrix of non-linear registration-derived dense deformation fields. New data for TLE subjects are projected in this space, under the assumption that the distributions of the projections of normal and patients are not identical and can be used for lateralization. Results are presented following PCA modeling of the left medial temporal lobe only for all subjects. It is shown that linear discriminant analysis of the eigencoordinates can be used to lateralize the seizure focus in TLE patients with a 75% accuracy. It is expected that adding a right temporal lobe model will improve lateralization results beyond those of HC volumetry.

关键词： MR intensity non-linear deformation fields jacobian matrices principal components analysis linear discriminant

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