Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Assessment of white matter microstructure in stroke patients using NODDI.
Diffusion weighted imaging (DWI) is widely used to study changes in white matter following stroke. In various studies employing diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI) modalities, it has been shown that fractional anisotropy (FA), mean diffusivity (MD), and generalized FA (GFA) can be used as measures of white matter tract integrity in stroke patients. However, these measures may be non-specific, as they do not directly delineate changes in tissue microstructure. ⋯ By computing NODDI indices over the entire brain in two stroke patients, and comparing tissue regions in ipsilesional and contralesional hemispheres, we demonstrate that NODDI modeling provides specific information on tissue microstructural changes. We also introduce an information theoretic analysis framework to investigate the non-local effects of stroke in the white matter. Our initial results suggest that the NODDI indices might be more specific markers of white matter reorganization following stroke than other measures previously used in studies of stroke recovery.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Respiratory rate estimation from the oscillometric waveform obtained from a non-invasive cuff-based blood pressure device.
The presence of respiratory activity in the electrocardiogram (ECG), the pulse oximeter's photoplethysmo-graphic and continuous arterial blood pressure signals is a well-documented phenomenon. In this paper, we demonstrate that such information is also present in the oscillometric signal acquired from automatic non-invasive blood pressure monitors, and may be used to estimate the vital sign respiratory rate (RR). ⋯ Results demonstrated a good RR estimation accuracy of our method when compared to the reference values extracted from the reference respiration waveforms (mean absolute error of 2.69 breaths/min), which is comparable to existing methods in the literature that extract RR from other physiological signals. The proposed method has been implemented in Java on the Android device for use in an mHealth platform.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Prediction of mortality from respiratory distress among long-term mechanically ventilated patients.
With the advent of inexpensive storage, pervasive networking, and wireless devices, it is now possible to store a large proportion of the medical data that is collected in the intensive care unit (ICU). These data sets can be used as valuable resources for developing and validating predictive analytics. In this report, we focus on the problem of prediction of mortality from respiratory distress among long-term mechanically ventilated patients using data from the publicly-available MIMIC-II database. ⋯ We also find that variables related to respiration rate have more predictive accuracy than variables related to oxygenation status. Ultimately, we have developed a model which predicts mortality from respiratory distress in the ICU with a cross-validated area-under-the-curve (AUC) of approximately 0.74. Four methodologies are utilized for model dimensionality-reduction: univariate logistic regression, multivariate logistic regression, decision trees, and penalized logistic regression.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Design and fabrication of a multi-electrode array for spinal cord epidural stimulation.
A detailed design, fabrication, characterization and test of a flexible multi-site platinum/polyimide based electrode array for electrical epidural stimulation in spinal cord prosthesis is described in this paper. Carefully designed 8.4 μm-thick structure fabrication flow achieves an electrode surface modification with 3.8 times enhanced effective surface area without extra process needed. Measured impedance and phase of two type of electrodes are 2.35±0.21 KΩ and 2.10±0.11 KΩ, -34.25±8.07° and -27.71±8.27° at 1K Hz, respectively. ⋯ The measured charge transfer resistance, double layer capacitance, and solution resistance are 1.9 KΩ, 220 nF and 15 KΩ, respectively. The results show that the fabricated array is applicable for electrical stimulation with well characterized parameters. Combined with a multichannel stimulator, this system provides a full solution for versatile neural stimulation applications.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Automatic lung tidal volumes estimation from tracheal sounds.
This paper presents a method to automatically estimate lung tidal volumes from the acoustic signals generated in the respiratory track. The signal is measured with an acoustic based sensor placed in the suprasternal notch. The method does not require any previous knowledge or modelling of the individual respiratory track, and relies on just one calibration parameter. ⋯ The subjects were simultaneously wearing a Wright respirometer which was used as a gold standard for comparison. Agreement between the two methods was assessed with Bland-Altman techniques. The results show the potential the technique has, integrated with a small acoustic sensor, for less-intrusive and even remote and/or continuous monitoring of lung tidal volumes.