| 1. |
- Moreno, Rodrigo, 1973-, et al.
(författare)
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Anisotropy Estimation of Trabecular Bone in Gray-Scale : Comparison Between Cone Beam and Micro Computed Tomography Data
- 2015
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Ingår i: Developments in Medical Image Processing and Computational Vision. - Cham : Springer. - 9783319134062 - 9783319134079 ; , s. 207-220
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Bokkapitel (refereegranskat)abstract
- Measurement of anisotropy of trabecular bone has clinical relevance in osteoporosis. In this study, anisotropy measurements of 15 trabecular bone biopsies from the radius estimated by different fabric tensors on images acquired through cone beam computed tomography (CBCT) and micro computed tomography (micro-CT) were compared. The results show that the generalized mean intercept length (MIL) tensor performs better than the global gray-scale structure tensor, especially when the von Mises-Fisher kernel is applied. Also, the generalized MIL tensor yields consistent results between the two scanners. These results suggest that this tensor is appropriate for estimating anisotropy in images acquired in vivo through CBCT.
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| 2. |
- Moreno, Rodrigo, 1973-, et al.
(författare)
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Correlations between fabric tensors computed on cone beam and microcomputed tomography images
- 2014
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Ingår i: Computational Vision and Medical Image Processing IV. - : CRC Press. - 9781138000810 ; , s. 393-398
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Konferensbidrag (refereegranskat)abstract
- Computational Vision and Medical Image Processing. VIPIMAGE 2013contains invited lectures and full papers presented at VIPIMAGE 2013 - IV ECCOMAS Thematic Conference on Computational Vision and Medical Image Processing (Funchal, Madeira Island, Portugal, 14-16 October 2013). International contributions from 16 countries provide a comprehensive coverage of the current state-of-the-art in the fields of: 3D Vision; Computational Bioimaging and Visualization; Computational Vision and Image Processing applied to Dental Medicine; Computational Vision; Computer Aided Diagnosis, Surgery, Therapy, and Treatment; Data Interpolation, Registration, Acquisition and Compression; Image Processing and Analysis; Image Segmentation; Imaging of Biological Flows; Medical Imaging; Physics of Medical Imaging; Shape Reconstruction; Signal Processing; Simulation and Modeling; Software Development for Image Processing and Analysis; Telemedicine Systems and their Applications; Trabecular Bone Characterization; Tracking and Analysis of Movement; Virtual Reality.Related techniques covered in this book include the level set method, finite element method, modal analyses, stochastic methods, principal and independent components analysis and distribution models. Computational Vision and Medical Image Processing. VIPIMAGE 2013 is useful to academics, researchers and professionals in Biomechanics, Biomedical Engineering, Computational Vision (image processing and analysis), Computer Sciences, Computational Mechanics and Medicine.
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| 3. |
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| 4. |
- Moreno, Rodrigo, et al.
(författare)
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Estimation of Trabecular Thickness in Gray-Scale Images Through Granulometric Analysis
- 2012
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 9780819489630
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper extends to gray-scale the method proposed by Hildebrand and Ru ̈egsegger for estimating thickness of trabecular bone, which is the most used in trabecular bone research, where local thickness at a point is defined as the diameter of the maximum inscribed ball that includes that point. The proposed extension takes advantage of the equivalence between this method and the opening function computed for the granulometry generated by the opening operation of mathematical morphology with ball-shaped structuring elements of different radii. The proposed extension (a) uses gray-scale instead of binary mathematical morphology, (b) uses all values of the pattern spectrum of the granulometry instead of the maximum peak as used for binary images, (c) corrects bias on local thickness estimations generated by partial volume effects, and (d) uses the gray-scale as a weighting function for global thickness estimation. The proposed extension becomes equivalent to the original method when it is applied to binary images. A new non-flat structuring element is also proposed in order to reduce the discretization errors generated by traditional flat structuring elements. Translation invariance can be attained by up-sampling the images through interpolation by a factor of two. Results for synthetic and real images show that the quality of the measurements obtained through the original method strongly depend on the binarization process, whereas the measurements obtained through the proposed extension does not. Consequently, the proposed extension is more appropriate for images with limited resolution where binarization is not trivial.
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| 5. |
- Moreno, Rodrigo, 1973-, et al.
(författare)
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Evaluation of the plate-rod model assumption of trabecular bone
- 2012
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Ingår i: 9th IEEE International Symposium on Biomedical Imaging (ISBI), 2012. - : IEEE Press. - 9781457718571 ; , s. 470-473
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Konferensbidrag (refereegranskat)abstract
- Trabecular bone has traditionally been assumed to be composed of plate- and rod-like trabeculae. This paper proposes a method to numerically evaluate the appropriateness of this assumption. In a first step, local constancy of thickness is estimated by comparing the maximum and mean diameter of the maximum inscribed balls centered at the medial axis/surface that includes every local point. In a second step, deviations from null curvature at the medial axis/surface are locally measured by comparing the geodesic and Euclidean distances from a point to its neighbors in the medial axis/surface. Finally, these two measurements are combined in order to locally estimate the compliance of the dataset with the plate-rod model assumption. Experiments on synthetic datasets show that the proposed measurements can be used to decide the compliance of a 3D shape with the plate-rod model. Results on micro computed tomography images show that the plate-rod model is more valid for a vertebra than for a radius. Thus, especially for the radius, measurements based on this model should be complemented with the proposed measurements.
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| 6. |
- Moreno, Rodrigo, et al.
(författare)
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Generalizing the mean intercept length tensor for gray-level images
- 2012
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Ingår i: Medical physics (Lancaster). - : American Association of Physicists in Medicine. - 0094-2405. ; 39:7, s. 4599-4612
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The mean intercept length tensor is the most used technique to estimate microstructure orientation and anisotropy of trabecular bone. This paper proposes an efficient extension of this technique to gray-scale images based on a closed formulation of the mean intercept length tensor and a generalization using different angular convolution kernels.Methods: First, the extended Gaussian image is computed for the binary or gray-scale image. Second, the intercepts are computed for all possible orientations through an angular convolution with the half-cosine function. Finally, the tensor is computed by means of the covariance matrix. The complexity of the method is O(n + m) in contrast with O(nm) of traditional implementations, where n is the number of voxels in the image and m is the number of orientations used in the computations. The method is generalized by applying other angular convolution kernels instead of the half-cosine function. As a result, the anisotropy of the tensor can be controlled while keeping the eigenvectors intact.Results: The proposed extension to gray-scale yields accurate results for reliable computations of the extended Gaussian image and, unlike the traditional methodology, is not affected by artifacts generated by discretizations during the sampling of different orientations.Conclusions: Experiments show that the computations on both binary and gray-scale images are correlated, and that computations in gray-scale are more robust, enabling the use of the mean intercept length tensor to clinical examinations of trabecular bone. The use of kernels based on the von Mises-Fisher distribution is promising as the anisotropy can be adjusted with a parameter in order to improve its power to predict mechanical properties of trabecular bone.
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| 7. |
- Moreno, Rodrigo, 1973-, et al.
(författare)
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On the Efficiency of the Mean Intercept Length Tensor
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Mean Intercept Length tensor is one of the most used techniques to estimate microstructure orientation and anisotropy of materials from 2D or 3D binary images. This paper proposes an efficient implementation of this technique. First, the Extended Gaussian Image is computed for the binary image. Second, the intercepts are computed for all possible orientations through an angular convolution. Finally, the tensor is computed by means of the covariance matrix. The complexity of the method is O(n+m) in contrast with O(nm) of traditional implementations, where n is the number of voxels in the image and m is the number of orientations used in the computations.
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| 8. |
- Moreno, Rodrigo, et al.
(författare)
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Soft classification of trabeculae in trabecular bone
- 2011
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Ingår i: Biomedical Imaging: From Nano to Macro, 2011. - : IEEE. - 9781424441273 ; , s. 1641-1644
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Konferensbidrag (refereegranskat)abstract
- Classification of trabecular bone aims at discriminating different types of trabeculae. This paper proposes a method to perform a soft classification from binary 3D images. In a first step, the local structure tensor is used to estimate a membership degree of every voxel to three different classes, plate-, rod- and junction-like trabeculae. In a second step, the global structure tensor of plate-like trabeculae is compared with the local orientation of rod-like trabeculae in order to discriminate aligned from non-aligned rods. Results show that soft classification can be used for estimating independent parameters of trabecular bone for every different class, by using the classification as a weighting function.
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| 9. |
- Moreno, Rodrigo, 1973-, et al.
(författare)
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Techniques for Computing Fabric Tensors : A Review
- 2014
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Ingår i: Visualization and Processing of Tensors and Higher Order Descriptors for Multi-Valued Data. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642543005 - 9783642543012 ; , s. 271-292
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Bokkapitel (refereegranskat)abstract
- The aim of this chapter is to review different approaches that have been proposed to compute fabric tensors with emphasis on trabecular bone research. Fabric tensors aim at modeling through tensors both anisotropy and orientation of a material with respect to another one. Fabric tensors are widely used in fields such as trabecular bone research, mechanics of materials and geology. These tensors can be seen as semi-global measurements since they are computed in relatively large neighborhoods, which are assumed quasi-homogeneous. Many methods have been proposed to compute fabric tensors. We propose to classify fabric tensors into two categories: mechanics-based and morphology-based. The former computes fabric tensors from mechanical simulations, while the latter computes them by analyzing the morphology of the materials. In addition to pointing out advantages and drawbacks for each method, current trends and challenges in this field are also summarized.
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