| 1. |
- Altinay, Doreen, et al.
(author)
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On the estimation of extrinsic and intrinsic parameters for optical microscope calibration
- 2010
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In: Proc. 2010 International Conference on Digital Image Computing: Techniques and Applications (DICTA). - 9781424488162 ; , s. 190 - 195
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Conference paper (peer-reviewed)abstract
- This paper compares several camera calibration methods on the estimation of specific extrinsic and intrinsic parameters. Good estimates of the chosen parameters, rotation and radial lens distortion are essential to increase the accuracy of quantitative measurements and to accurately stitch single field-of-view-based images together. The parameters are obtained using two selected methods on different objective magnifications on a microscope system using a fixed grid calibration pattern. We evaluate two methods and show that the rotation angles from one of the methods is consistent with a simple homography while the other estimates a consistently smaller angle. The radial distortion estimates are both very small and relate to a distortion of less than one pixel.
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| 2. |
- McClymont, Darryl, et al.
(author)
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Improving the discrimination of benign and malignant breast MRI lesions using the apparent diffusion coefficient
- 2010
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In: Proc. 2010 International Conference on Digital Image Computing: Techniques and Applications (DICTA). - 9781424488162 ; , s. 569 - 574
-
Conference paper (peer-reviewed)abstract
- This paper presents an investigation of the apparent diffusion coefficient (ADC) for improving the discrimination of benign and malignant lesions in breast magnetic resonance imaging (MRI). In particular a method is presented for automatically selecting hyper intense tumour voxels in dynamic contrast enhanced (DCE) MRI data and evaluating their average ADC in the corresponding diffusion-weighted (DW) MRI data. The method was applied to ten breast MRI datasets obtained from routine clinical practice. The results demonstrate that the combination of the relative signal increase (DCE-MRI) with the apparent diffusion coefficient (DW-MRI) leads to better discrimination than with either feature alone. The results also suggest that it is important to acquire the DW-MRI data in a consistent fashion, i.e. either before or after the acquisition of the DCE-MRI data.
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| 3. |
- Mehnert, Andrew, 1967, et al.
(author)
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Two non-linear parametric models of contrast enhancement for DCE-MRI of the breast amenable to fitting using linear least squares
- 2010
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In: Proc. 2010 International Conference on Digital Image Computing: Techniques and Applications (DICTA). - IEEE Computer Society, Los Alamitos, CA, USA : IEEE Computer Society. - 9781424488162 ; , s. 611-616
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Conference paper (peer-reviewed)abstract
- This paper proffers two non-linear empirical parametric models - linear slope and Ricker - for use in characterising contrast enhancement in dynamic contrast enhanced (DCE) MRI. The advantage of these models over existing empirical parametric and pharmacokinetic models is that they can be fitted using linear least squares (LS). This means that fitting is quick, there is no need to specify initial parameter estimates, and there are no convergence issues. Furthermore the LS fit can itself be used to provide initial parameter estimates for a subsequent NLS fit (self-starting models). The results of an empirical evaluation of the goodness of fit (GoF) of these two models, measured in terms of both MSE and R2, relative to a two-compartment pharmacokinetic model and the Hayton model are also presented. The GoF was evaluated using both routine clinical breast MRI data and a single high temporal resolution breast MRI data set. The results demonstrate that the linear slope model fits the routine clinical data better than any of the other models and that the two parameter self-starting Ricker model fits the data nearly as well as the three parameter Hayton model. This is also demonstrated by the results for the high temporal data and for several temporally sub-sampled versions of this data.
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