| 1. |
- Gal, Yaniv, et al.
(författare)
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A new denoising method for dynamic contrast-enhanced MRI
- 2008
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Ingår i: Proc. 2008 Annual International Conference of the IEEE Engineering in Medicine and Biology Society. - 9781424418145 ; , s. 847 - 850
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Konferensbidrag (refereegranskat)abstract
- This paper presents a new algorithm for denoising dynamic contrast-enhanced (DCE) MR images. The algorithm is called Dynamic Non-Local Means and is a novel variation on the Non-Local Means (NL-Means) algorithm. It exploits the redundancy of information in the DCE-MRI sequence of images. An evaluation of the performance of the algorithm relative to six other denoising algorithms—Gaussian filtering, the original NL-Means algorithm, bilateral filtering, anisotropic diffusion filtering, the wavelets adaptive multiscale products threshold method, and the traditional wavelet thresholding method—is also presented. The evaluation was performed by two groups of expert observers—18 signal/image processing experts, and 9 clinicians (8 radiographers and 1 radiologist)—using real DCE-MRI data. The results of the evaluation provide evidence, at the α=0.05 level of significance, that both groups of observers deem the DNLM algorithm to perform visually better than all of the other algorithms.
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| 2. |
- Gal, Yaniv, et al.
(författare)
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An evaluation of four parametric models of contrast enhancement for dynamic magnetic resonance imaging of the breast
- 2007
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Ingår i: Proc. 2007 Annual International Conference of the IEEE Engineering in Medicine and Biology Society. - 9781424407873 ; , s. 71 - 74
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Konferensbidrag (refereegranskat)abstract
- This paper presents an empirical evaluation of the goodness-of-fit (GOF) of four parametric models of contrast enhancement for dynamic resonance imaging of the breast: the Tofts, Brix, and Hayton pharmacokinetic models, and a novel empiric model. The goodness-of-fit of each model was evaluated with respect to: (i) two model-fitting algorithms (Levenberg- Marquardt and Nelder-Mead) and two fitting tolerances; and (ii) temporal resolution. In the first case the GOF was measured using data from three dynamic contrast-enhanced (DCE) MRI data sets from routine clinical examinations: one case with benign enhancement, one with malignant enhancement, and one with normal findings. Results are presented for fits to both the whole breast volume and to a selected region of interest. In the second case the GOF was measured by first fitting the models to several temporally sub-sampled versions of a custom high temporal resolution data set (subset of the breast volume containing a malignant lesion), and then comparing the fitted results to the original full temporal resolution data. Our results demonstrate that under the various optimization conditions considered, in general, both the proposed empiric model and the Hayton model fit the data equally well and that both of these models fit the data better than the Tofts and Brix models.
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| 3. |
- Gal, Yaniv, et al.
(författare)
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Automatic segmentation of enhancing breast tissue in dynamic contrast-enhanced MR images
- 2007
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Ingår i: Proc. 2007 Biennial Conference of the Australian Pattern Recognition Society on Digital Image Computing Techniques and Applications (DICTA). - 0769530672 ; , s. 124-129
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Konferensbidrag (refereegranskat)abstract
- We present a novel method for the segmentation of enhancing breast tissue, suspicious of malignancy, in dynamic contrast-enhanced (DCE) MR images. The method is based on seeded region growing and merging using criteria based on both the original image intensity values and the fitted parameters of a novel empiric parametric model of contrast enhancement. We present the results of the application of the method to DCE-MRI data sets originating from breast MRI examinations of 24 subjects (10 cases of benign and 14 cases of malignant enhancement). The results show that the segmentation method has 100% sensitivity for the detection of suspicious regions independently identified by a radiologist. The results suggest that the method has potential both as a tool to assist the clinician with the task of locating suspicious tissue and as input to a computer assisted diagnostic system for generating quantitative features for automatic classification of suspicious tissue.
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| 4. |
- Hill, Andrew, et al.
(författare)
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Dynamic breast MRI: Image registration and its impact on enhancement curve estimation
- 2006
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Ingår i: Proc. 2006 Annual International Conference of the IEEE Engineering in Medicine and Biology Society. - 1424400325 ; , s. 3049 - 3052
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Konferensbidrag (refereegranskat)abstract
- A novel algorithm for performing registration of dynamic contrast-enhanced (DCE) MRI data of the breast is presented. It is based on an algorithm known as iterated dynamic programming originally devised to solve the stereo matching problem. Using artificially distorted DCE-MRI breast images it is shown that the proposed algorithm is able to correct for movement and distortions over a larger range than is likely to occur during routine clinical examination. In addition, using a clinical DCE-MRI data set with an expertly labeled suspicious region, it is shown that the proposed algorithm significantly reduces the variability of the enhancement curves at the pixel level yielding more pronounced uptake and washout phases
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| 5. |
- Lederman, Judith S., et al.
(författare)
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Completing the progression establishing an international baseline of primary, middle and secondary students’ views of scientific inquiry
- 2023
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Ingår i: International Journal of Science Education. - : Routledge. - 0950-0693 .- 1464-5289.
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of scientific inquiry (SI) is considered essential to the development of an individual's Scientific Literacy (SL) and therefore, SI is included in many international science education reform documents. Two previous large scale international studies assessed the SI understandings of students entering middle school and secondary students at the end of their formal K-12 science education. The purpose of this international project was to use the VASI-E to collect data on what primary level students have learned about SI in their first few years of school. This study adds to previous research to bridge the landscape of SI understandings now with representation from primary, middle and high school samples. A total of 4,238 students from 35 countries/regions spanning six continents participated in the study. The results show that globally, primary students are not adequately informed about SI for their age group. However, when compared with the students in the previous international studies (grades seven and 12), the primary students' understandings were surprisingly closer to the levels of understanding of SI of the secondary school students than those in the seventh grade study.
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| 6. |
- Mehnert, Andrew, et al.
(författare)
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Dynamic breast MRI visualised through colour mapping
- 2005
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Ingår i: Proceedings SSBA 2005. ; , s. 9-12
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The pattern of change of signal intensity over time in contrast enhanced MR images of the breast is a useful indicator of malignancy. In this paper a new pixel mapping method for visualising the time course of the contrast uptake is presented. The method reduces the sequence of images of a single spatial slice over time to a single colour-coded image. This is achieved by fitting a linear-slope model pixel-wise to the slice time series and using the fitted parameters to define modified HSV colour space coordinates. The model parameters are related to the shape of the signal intensity-time curve at each pixel. The effect is that pixels with rapid uptake and significant postcontrast enhancement appear brighter and more saturated, whilst the nature and degree of intermediate and late postcontrast enhancement is reflected in the colour hue. Preliminary results are reported for six subjects with suspicious MRI findings subsequently confirmed by pathology. The results suggest that the method shows promise as a replacement for, or adjunct to, the review of the raw time series data and/or associated difference images in the clinical setting.
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| 7. |
- Mehnert, Andrew, 1967, et al.
(författare)
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Registration evaluation of dynamic breast MR images
- 2005
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Ingår i: Proceedings of the APRS Workshop on Digital Image Computing (WDIC2005). ; , s. 21-26
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Konferensbidrag (refereegranskat)abstract
- The interpretation of dynamic contrast-enhanced breast MR images is predicated on the assumption of minimal voxel movement during the time course of the image acquisition. Misalignment of the dynamic image sequence as a result of movement during image acquisition can lead to potentially misleading diagnostic conclusions. In this paper a new methodology is presented for assessing the degree of in-plane (intra-slice) movement in a dynamic image sequence. The method is demonstrated on data from six subjects. The conclusion is that the method makes it possible to quantitatively qualify the accuracy of computed enhancement curves and more importantly to identify unacceptably poor registration.
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| 8. |
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| 9. |
- Mehnert, Andrew, et al.
(författare)
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Visualisation of the pattern of contrast enhancement in dynamic breast MRI
- 2005
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Ingår i: WDIC 2005.
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Konferensbidrag (refereegranskat)abstract
- A new pixel-mapping method for visualising contrast uptake in dynamic MR images of the breast is presented. The method reduces the sequence of images of a single spatial slice over time to a single colour-coded image. This is achieved by fitting a linear-slope model pixel-wise to the slice time series and using the fitted parameters to define HSV colour space coordinates. The model parameters are related to the shape of the signal intensity-time curve at each pixel. The effect is that pixels with rapid and significant initial postcontrast enhancement appear brighter and more saturated, whilst the nature and degree of intermediate and late postcontrast enhancement is reflected in the colour hue. Preliminary results are reported for six subjects with suspicious MRI findings subsequently confimed by pathology. The results suggest that the method showspromise as a replacement for, or adjunct to, the review of the raw time series data and/or associated difference images in the clinical setting.
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| 10. |
- Vidholm, Erik, et al.
(författare)
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Hardware accelerated visualization of parametrically mapped dynamic breast MRI data
- 2007
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Ingår i: Proceedings of MICCAI workshop: Interaction in Medical Image Analysis and Visualization. - 978 0 643 09521 2 - 9780643095212 ; , s. 33-40, s. 33-40
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Konferensbidrag (refereegranskat)abstract
- We present a new approach to visualising parametric vol-umes obtained in voxel-wise model fitting of dynamic contrast-enhanced(DCE) MRI data of the breast. The visualisation makes use of hardware-accelerated rendering to obtain an interactive, 3D colour-correct maxi-mum intensity projection (MIP). The method has been realised in soft-ware that permits the user to not only interactively visualise the paramet-ric volume but also to delineate 3D regions of interest using a 2D slice-wise interface. Experimental results, based on 14 DCE-MRI data setsfrom routine clinical practice, show that using the visualisation/tracingtool a medically qualified operator can achieve the same sensitivity forthe detection of malignancy as a radiologist using conventional manualinterpretation, but with better specificity. The results demonstrate thatthe visualisation methodology/software has potential as a tool for assist-ing the radiologist with the task of interpreting 4D DCE-MRI data inthe routine clinical setting.
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