| 1. |
- Corino, V. D. A., et al.
(author)
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A Gaussian mixture model for time-frequency analysis during atrial fibrillation electrocardiograms
- 2007
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In: 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS 2007.. - 1557-170X. - 9781424407880 ; , s. 271-274
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Conference paper (peer-reviewed)abstract
- During atrial fibrillation (AF), time-frequency analysis of atrial signal has been applied to describe fibrillatory frequency trends. Recently, temporal changes in spectral shape have been investigated using the spectral profile technique. This profile is computed recursively by fitting each short-time log-spectrum to a spectral template, using amplitude scaling and frequency shifting. The purpose of the present study was to develop a Gaussian mixture model of the spectral profile in order to characterize the shape of AF waveforms. A novel index is introduced, the so-called harmonic index (HI), which reflects properties of the fundamental frequency peak and related harmonics peaks as estimated from the model. The index was tested on recordings from 9 patients with persistent AF, obtained before and after exercise testing. The HI succeeded in monitoring the response to exercise, i.e. change in the spectral profile to a less harmonic pattern, which is consistent with a reduction in AF organization (HI: 0.61±0.11 vs. 0.50±0.19, rest vs. exercise; p≪0.05).
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| 2. |
- Gund, Anna, 1980, et al.
(author)
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Design Evaluation of a Home-Based Telecare System for Chronic Heart Failure Patients
- 2008
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In: Engineering in Medicine and Biology Society, 2008. EMBS 2008. 30th Annual International Conference of the IEEE. - : IEEE. - 1557-170X. - 9781424418145 ; , s. 5851-5854, s. 5851-5854
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Conference paper (peer-reviewed)abstract
- In order to improve the care of Chronic Heart Failure (CHF) patients, a system has been developed for monitoring symptoms and document subjective judgments on health conditions in a home environment. Since system usability is an important issue, a two step evaluation of the solution was conducted. First a ten-patient survey was conducted, which was aimed at spotting possible problem areas. The second step involved a small trial in a home setting with CHF patients. The results are promising, indicating that the system is user friendly and easy to use, and that it is suitable as a prototype for the intended use.
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| 3. |
- Herreros, Alberto, et al.
(author)
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An Algorithm for Phase-Space Detection of the P Characteristic Points
- 2007
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In: PROC. annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC2007). Lyon, France, Aug 23-26, 2007. - 1557-170X. ; 1, s. 2004-2007
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Conference paper (peer-reviewed)abstract
- A new algorithm, based on embedding phase space, to detect the P-wave characteristic points of an ECG signal is reported in this paper. The multi-lead ECG is transformed into points of an embedding phase space where similar ECG morphologies are converted into phase space points that are close using some distance measure. The algorithm is robust with respect to the type of selected characteristic points (onset, peak and end), morphology changes, baseline oscillations and high frequency noise. The performance of the algorithm has been succesfully validated using both simulated and real ECG signals.
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| 4. |
- Hill, Andrew, et al.
(author)
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Edge intensity normalization as a bias field correction during balloon snake segmentation of breast MRI
- 2008
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In: Proc. 2008 Annual International Conference of the IEEE Engineering in Medicine and Biology Society. - 1557-170X. ; , s. 3040 - 3043
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Conference paper (peer-reviewed)abstract
- Segmentation of fat suppressed dynamic contrast enhanced MRI (DCE-MRI) image data can pose significant problems because of the inherently poor signal-to-noise ratio (SNR) and intensity variations due to the bias field. Segmentation methods such as balloon snakes, while able to operate in a poor SNR environment, are sensitive to variations in edge intensity, which are regularly encountered within DCE-MRI due to the bias field. In order to overcome the effects of the bias field, an intensity normalization based on the strength of the strongest edge, i.e. the skin-air-boundary, is proposed and evaluated. This normalization allows balloon segmentations to be run three times faster while maintaining, or even improving accuracy.
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| 5. |
- Karlsson, M, et al.
(author)
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Wireless system for real-time recording of heart rate variability for home nursing.
- 2005
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In: Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference. - 1557-170X. ; 4, s. 3717-9
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Journal article (peer-reviewed)abstract
- Modern wireless communication technologies offer new possibilities for patient monitoring in hospitals, as well as at home or in outdoor environments. In this paper, we present a wireless system for ECG recordings and real-time analysis of heart rate variability (HRV). The system also makes it possible for distance consultation, for example with a specialist in cardiology, with the help of a WEB-solution.
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| 6. |
- Köhler, Per, et al.
(author)
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Flexible multi electrode brain-machine interface for recording in the cerebellum.
- 2009
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In: IEEE Engineering in Medicine and Biology Society. Conference Proceedings. - 1557-170X. ; 1, s. 536-538
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Journal article (peer-reviewed)abstract
- A new type of chip based microelectrode for acute electrophysiological recordings in the CNS has been developed. It's designed to be adaptable to a multitude of specific neuronal environments, in this study the cerebellar cortex of rat and cat. Photolithographically patternened SU-8 is used to yield flexible and biocompatible penetrating shanks with gold leads. Electrodes with an impedance of about 300 kOmega at 1kHz have excellent signal to noise ratio in acute recordings in cat cerebellum.
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| 7. |
- Löfhede, Johan, et al.
(author)
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Comparing a Supervised and an Unsupervised Classification Method for Burst Detection in Neonatal EEG
- 2008
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In: Proceedings of Engineering in Medicine and Biology Society, EMBS 2008. 30th Annual International Conference of the IEEE, 20-24 August, 2008. - : IEEE. - 1557-170X. - 9781424418145 ; , s. 3836-3839
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Conference paper (peer-reviewed)abstract
- Hidden Markov Models (HMM) and Support Vector Machines (SVM) using unsupervised and supervised training, respectively, were compared with respect to their ability to correctly classify burst and suppression in neonatal EEG. Each classifier was fed five feature signals extracted from EEG signals from six full term infants who had suffered from perinatal asphyxia. Visual inspection of the EEG by an experienced electroencephalographer was used as the gold standard when training the SVM, and for evaluating the performance of both methods. The results are presented as receiver operating characteristic (ROC) curves and quantified by the area under the curve (AUC). Our study show that the SVM and the HMM exhibit similar performance, despite their fundamental differences.
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| 8. |
- Löfhede, Johan, 1978, et al.
(author)
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Comparison of Three Methods for Classifying Burst and Suppression in the EEG of Post Asphyctic Newborns
- 2007
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In: Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE. - : IEEE. - 1557-170X. - 9781424407880 - 9781424407873 ; , s. 5136-5139
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Conference paper (peer-reviewed)abstract
- Fisher's linear discriminant, a feed-forward neural network (NN) and a support vector machine (SVM) are compared with respect to their ability to distinguish bursts from suppression in burst-suppression electroencephalogram (EEG) signals using five features inherent in the EEG as input. The study is based on EEG signals from six full term infants who have suffered from perinatal asphyxia, and the methods have been trained with reference data classified by an experienced electroencephalographer. The results are summarized as area under the curve (AUC) values derived from receiver operating characteristic (ROC) curves for the three methods, and show that the SVM is slightly better than the others, at the cost of a higher computational complexity.
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| 9. |
- Löfhede, Johan, 1978, et al.
(author)
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Detection of bursts in the EEG of post asphyctic newborns
- 2006
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In: 2006 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. - 1557-170X. - 9781424400324 ; , s. 2179-2182, s. 5-6
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Conference paper (peer-reviewed)abstract
- Eight features inherent in the electroencephalogram (EEG) have been extracted and evaluated with respect to their ability to distinguish bursts from suppression in burst-suppression EEG. The study is based on EEG from six full term infants who had suffered from lack of oxygen during birth. The features were used as input in a neural network, which was trained on reference data segmented by an experienced electroencephalographer. The performance was then evaluated on validation data for each feature separately and in combinations. The results show that there are significant variations in the type of activity found in burst-suppression EEG from different subjects, and that while one or a few features seem to be sufficient for most patients in this group, some cases require specific combinations of features for good detection to be possible.
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| 10. |
- Martinez, J P, et al.
(author)
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Accuracy of QT Measurement in the EASI-derived 12-lead ECG
- 2006
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In: Conference proceedings (IEEE Engineering in Medicine and Biology Society. Conf.). - 1557-170X. ; 1, s. 3986-3989
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Conference paper (peer-reviewed)abstract
- The purpose of this study is to assess QT interval measurements from the EASI 12-lead ECG as compared to the standard 12-lead ECG. The QT interval was automatically measured in simultaneously recorded standard and EASI 12- lead ECGs, using a validated wavelet-based delineator. The agreement between the two sets of measurements was quantified both on a lead-by-lead basis and a multilead basis. The results show an acceptable agreement between QT measurements in the two lead systems, with correlation coefficients (CC) 0.91-0.98 depending on the lead. Standard deviations range from 9.2 ms to 26.4 ms depending on the selected lead. In a few patients large inter-system differences were found, mainly due to different T wave morphologies. Using a multilead delineation, QT intervals were considerably more stable than single-lead measurements and resulted in a much better agreement between the two lead systems (CC: 0.98, QT difference: 1.1 ms ± 9.8 ms). Thus, EASI-derived 12- lead ECG may be used for reliable QT monitoring when the multilead delineation approach is adopted.
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