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Tensor Field Visualisation using Adaptive Filtering of Noise Fields combined with Glyph Rendering
Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.ORCID iD: 0000-0003-1395-8296
Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
2002 (English)In: IEEE Visualization 2002 Conference, IEEE , 2002, 371-378 p.Conference paper, Published paper (Refereed)
Abstract [en]

While many methods exist for visualising scalar and vector data, visualisation of tensor data is still troublesome. We present a method for visualising second order tensors in three dimensions using a hybrid between direct volume rendering and glyph rendering.

An overview scalar field is created by using three-dimensional adaptive filtering of a scalar field containing noise. The filtering process is controlled by the tensor field to be visualised, creating patterns that characterise the tensor field. By combining direct volume rendering of the scalar field with standard glyph rendering methods for detailed tensor visualisation, a hybrid solution is created.

A combined volume and glyph renderer was implemented and tested with both synthetic tensors and strain-rate tensors from the human heart muscle, calculated from phase contrast magnetic resonance image data. A comprehensible result could be obtained, giving both an overview of the tensor field as well as detailed information on individual tensors.

Place, publisher, year, edition, pages
IEEE , 2002. 371-378 p.
Keyword [en]
Tensor, Visualisation, Volume rendering, Glyph rendering, Hybrid rendering, Strain-rate
National Category
Medical and Health Sciences Medical Laboratory and Measurements Technologies
Identifiers
URN: urn:nbn:se:liu:diva-14011OAI: oai:DiVA.org:liu-14011DiVA: diva2:22460
Available from: 2006-10-04 Created: 2006-10-04 Last updated: 2013-09-03Bibliographically approved
In thesis
1. Multidimensional MRI of Cardiac Motion: Acquisition, Reconstruction and Visualization
Open this publication in new window or tab >>Multidimensional MRI of Cardiac Motion: Acquisition, Reconstruction and Visualization
2006 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Methods for measuring deformation and motion of the human heart in-vivo are crucial in the assessment of cardiac function. Applications ranging from basic physiological research, through early detection of disease to follow-up studies, all benefit from improved methods of measuring the dynamics of the heart. This thesis presents new methods for acquisition, reconstruction and visualization of cardiac motion and deformation, based on magnetic resonance imaging.

Local heart wall deformation can be quantified in a strain rate tensor field. This tensor field describes the local deformation excluding rigid body translation and rotation. The drawback of studying this tensor-valued quantity, as opposed to a velocity vector field, is the high dimensionality of the tensor. The problem of visualizing the tensor field is approached by combining a local visualization that displays all degrees of freedom for a single tensor with an overview visualization using a scalar field representation of the complete tensor field. The scalar field is obtained by iterated adaptive filtering of a noise field.

Several methods for synchronizing the magnetic resonance imaging acquisition to the heart beat have previously been used to resolve individual heart phases from multiple cardiac cycles. In the present work, one of these techniques is extended to resolve two temporal dimensions simultaneously, the cardiac cycle and the respiratory cycle. This is combined with volumetric imaging to produce a five-dimensional data set. Furthermore, the acquisition order is optimized in order to reduce eddy current artifacts.

The five-dimensional acquisition either requires very long scan times or can only provide low spatiotemporal resolution. A method that exploits the variation in temporal bandwidth over the imaging volume, k-t BLAST, is described and extended to two simultaneous temporal dimensions. The new method, k-t2 BLAST, allows simultaneous reduction of scan time and improvement of spatial resolution.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2006. 51 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1262
Keyword
MRI, cardiac, motion, reconstruction
National Category
Computer Vision and Robotics (Autonomous Systems)
Identifiers
urn:nbn:se:liu:diva-7468 (URN)LIU-TEK-LIC-2006:43 (Local ID)91-85523-37-2 (ISBN)LIU-TEK-LIC-2006:43 (Archive number)LIU-TEK-LIC-2006:43 (OAI)
Presentation
2006-09-15, Wrannesalen, CMIV, Huvudblocket, Universitetssjukhuset, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2006-10-04 Created: 2006-10-04 Last updated: 2013-08-28
2. Multidimensional MRI  of Myocardial Dynamics: Acquisition, Reconstruction and Visualization
Open this publication in new window or tab >>Multidimensional MRI  of Myocardial Dynamics: Acquisition, Reconstruction and Visualization
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Methods for measuring deformation and motion of the human heart in-vivo are crucial in the assessment of cardiac function. Applications ranging from basic physiological research, through early detection of disease to follow-up studies, all rely on the quality of the measurements of heart dynamics. This thesis presents new improved magnetic resonance imaging methods for acquisition, image reconstruction and visualization of cardiac motion and deformation.As the heart moves and changes shape during the acquisition, synchronization to the heart dynamics is necessary. Here, a method to resolve not only the cardiac cycle but also the respiratory cycle is presented. Combined with volumetric imaging, this produces a five-dimensional data set with two cyclic temporal dimensions. This type of data reveals unique physiological information, such as interventricular coupling in the heart in different phases of the respiratory cycle.The acquisition can also be sensitized to motion, measuring not only the magnitude of the magnetization but also a signal proportional to local velocity or displacement. This allows for quantification of the motion which is especially suitable for functional study of the cardiac deformation. In this work, an evaluation of the influence of several factors on the signal-to-noise ratio is presented for in-vivo displacement encoded imaging. Additionally, an extension of the method to acquire multiple displacement encoded slices in a single breath hold is also presented.Magnetic resonance imaging is usually associated with long scan times, and many methods exist to shorten the acquisition time while maintaining acceptable image quality. One class of such methods involves acquiring only a sparse subset of k-space. A special reconstruction is then necessary in order to obtain an artifact-free image. One family of these reconstruction techniques tailored for dynamic imaging is the k-t BLAST approach, which incorporates data-driven prior knowledge to suppress aliasing artifacts that otherwise occur with the sparse sampling. In this work, an extension of the original k-t BLAST method to two temporal dimensions is presented and applied to data acquired with full coverage of the cardio-respiratory cycles. Using this technique, termed k-t2 BLAST, simultaneous reduction of scan time and improved spatial resolution is demonstrated. Further, the loss of temporal fidelity when using the k-t BLAST approach is investigated, and an improved reconstruction is proposed for the application of cardiac function analysis.Visualization is a crucial part of the imaging chain. Scalar data, such as regular anatomical images, are straightforward to display. Myocardial strain and strain-rate, however, are tensor quantities which do not lend themselves to direct visualization. The problem of visualizing the tensor field is approached in this work by combining a local visualization that displays all degrees of freedom for a single tensor with an overview visualization using a scalar field representation of the complete tensor field. The scalar field is obtained by iterated adaptive filtering of a noise field, creating a continuous geometrical representation of the myocardial strain-rate tensor field.The results of the work presented in this thesis provide opportunities for improved imaging of myocardial function, in all areas of the imaging chain; acquisition, reconstruction and visualization.

 

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 71 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1287
Keyword
MRI, Cardiac motion, myocardial dynamics, strain, tensor, deformation, DENSE, k-t BLAST
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:liu:diva-51489 (URN)978-91-7393-494-7 (ISBN)
Public defence
2009-12-18, Conrad, Campus US, Linköpings Universitet, Linköping, 09:15 (English)
Opponent
Supervisors
Available from: 2009-11-30 Created: 2009-11-04 Last updated: 2013-08-28Bibliographically approved

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Sigfridsson, AndreasEbbers, TinoHeiberg, EinarWigström, Lars

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