177 results on '"Sejdić E"'
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2. Assessing interactions among multiple physiological systems during walking outside a laboratory: An Android based gait monitor
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Sejdić, E., Millecamps, A., Teoli, J., Rothfuss, M.A., Franconi, N.G., Perera, S., Jones, A.K., Brach, J.S., and Mickle, M.H.
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- 2015
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3. An Algorithm for Classification of Opening Snaps and Third Heart Sounds Based on Wavelet Decomposition
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Sejdić, E., Veledar, E., Magjarevic, Ratko, editor, and Jobbágy, Ákos, editor
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- 2012
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4. Baseline characteristics of cervical auscultation signals during various head maneuvers
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Jestrović, I., Dudik, J.M., Luan, B., Coyle, J.L., and Sejdić, E.
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- 2013
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5. List of Contributors
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Abed-Meraim, K., primary, Ahmad, J., additional, Aïssa-El-Bey, A., additional, Akan, A., additional, Akay, O., additional, Ali, S., additional, Alieva, T., additional, Amin, M.G., additional, Assous, S., additional, Auger, F., additional, Aviyente, S., additional, Awal, M.A., additional, Azemi, G., additional, Bastiaans, M.J., additional, Baraniuk, R.G., additional, Barbarossa, S., additional, Barkat, B., additional, Barroso, V., additional, Beghdadi, A., additional, Belouchrani, A., additional, Boashash, B., additional, Böhme, J.F., additional, Boudraa, A.-O., additional, Boudreaux-Bartels, G.F., additional, Carstens-Behrens, S., additional, Chandran, V., additional, Chassande -Mottin, E., additional, Colditz, P., additional, Djebbari, A., additional, Djukanović, S., additional, Djurović, I., additional, Dong, S., additional, El-Jaroudi, A., additional, Emresoy, M.K., additional, Ferguson, B.G., additional, Flandrin, P., additional, Frazer, G.J., additional, Frunzaverde, D., additional, Galleani, L., additional, Gholami, A., additional, Hassanpour, H., additional, Hlawatsch, F., additional, Hussain, Z.M., additional, Iem, B.-G., additional, Iordache, R., additional, Jawad, B.K., additional, Jones, G., additional, Jones, D.L., additional, Katkovnik, V., additional, Khan, N.A., additional, Lerga, J., additional, Leyman, A.R., additional, Linh-Trung, N., additional, Lindsey, A.R., additional, Lo, K.W., additional, Grady, W. Mack, additional, Marple, S.L., additional, Matz, G., additional, Mert, A., additional, Napolitano, A., additional, Oliveira, P.M., additional, Omidvarnia, A., additional, Onchis, D.M., additional, O’Shea, P.J., additional, Ouelha, S., additional, O’Toole, J.M., additional, Papandreou-Suppappola, A., additional, Powers, E.J., additional, Putland, G.R., additional, Rankine, L.J., additional, Ristic, B., additional, Salzenstein, F., additional, Saulig, N., additional, Sayeed, A.M., additional, Sejdić, E., additional, Sha’ameri, A.Z., additional, Shafi, I., additional, Shah, S.I., additional, Shin, Y.-J., additional, Simeunović, M., additional, Stanković, S., additional, Stanković, L.J., additional, Stevenson, N.J., additional, Sucic, V., additional, Suppappola, S.B., additional, Tauböck, G., additional, Touati, S., additional, Tsitsvero, M., additional, van Leest, A.J., additional, Ventosa, S., additional, Williams, W.J., additional, Xia, X.-G., additional, Zarjam, P., additional, and Zhang, Y.D., additional
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- 2016
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6. An Algorithm for Classification of Opening Snaps and Third Heart Sounds Based on Wavelet Decomposition
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Sejdić, E., primary and Veledar, E., additional
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- 2011
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7. Measures, Performance Assessment, and Enhancement of TFDs
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Boashash, B., Touati, S., Auger, F., Flandrin, P., Chassande-Mottin, E., Stanković, L.J., Sucic, V., Khan N., Sejdić, E., Saulig, N., Shafi, I., Ahmad, J., and Shah, S.I.
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Performance assessment ,Wavelet ,Compressed sensing ,Section (archaeology) ,Wavelet transform ,Filter (signal processing) ,Gabor transform ,Affine transformation ,Entropy (energy dispersal) ,Algorithm ,Mathematics - Abstract
This chapter describes a number of time-frequency (t, f) performance quality measures specifically developed as criteria for performance enhancement for a given application. The adopted performance measures are defined using objective criteria followed by time-frequency distribution (TFD) enhancement methods to improve the (t, f) concentration, resolution, and readability of TFDs. The topic is covered in nine sections. Hyperbolic FM signals are well described by the affine Wigner-Ville distribution (WVD), a method related to time-scale analysis and the wavelet transform (Section 7.1). A general procedure for enhancing the time-frequency resolution and readability of TFDs is the reassignment principle described in Section 7.2. Techniques for measuring the concentration of TFDs and for automatic optimization of their parameters are presented based on entropy measures (Section 7.3). Another approach defines a resolution performance measure using local measurements in the (t, f) domain, such as relative amplitudes of auto-terms and cross-terms (Section 7.4). Then, a comparison of postprocessing methods in the (t, f) domain is presented (Section 7.5). The last four topics focus on time-frequency compressive sensing (Section 7.6); signal complexity estimation using (t, f) entropy measures (Section 7.7); time-frequency analysis using neural networks (Section 7.8); and attempts to unify time-frequency, time-scale, filter banks, wavelets, and the discrete-time Gabor transform using product functions and cascaded frames are presented briefly as they may assist in the selection of the best-performing method for a given application (Section 7.9).
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- 2016
8. Time-frequency methodologies in neurosciences
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Boashash, B., Stevenson, N.J., Rankine, L.J., Azemi, G., Sejdić, E., Aviyente, S., Akan, A., Mert, A., Dong, S., Omidvarnia, A., Zarjam, P., O'Toole, J.M., and Colditz, P.
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medicine.diagnostic_test ,Computer science ,business.industry ,Section (typography) ,Time frequency ,020206 networking & telecommunications ,Pattern recognition ,02 engineering and technology ,Electroencephalography ,Time–frequency analysis ,03 medical and health sciences ,0302 clinical medicine ,Eeg data ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Artificial intelligence ,Medical diagnosis ,business ,030217 neurology & neurosurgery - Abstract
This chapter presents a number of time-frequency (t,f) techniques that can provide advanced solutions to several problems in neuro-sciences with focus on the monitoring of brain abnormalities using EEG and other physiological modalities (t,f) characteristics as a diagnosis and prognosis tool. The methods presented illustrate the improved performance obtained by using a time-frequency approach to process EEG data, including a focus on detecting abnormalities in sick newborns in a Neonatal Intensive Care Unit (NICU) as well as mental health issues in elderlies. The chapter starts by presenting methods for the assessment of Newborn EEG and ECG abnormalities using a time-frequency identification approach (Section 16.1). Next, the important question of (t,f) modeling of nonstationary signals is discussed with illustration on newborn EEGs (Section 16.2); Then, the use of (t,f) features for nonstationary signal classification is illustrated on an application to newborn EEG burst-suppression detection (Section 16.3); an application relevant to the elderly is described where a time-varying analysis of brain networks uses the EEG for the detection of Alzheimer disease (Section 16.4). Another method of time-frequency analysis is described that involves EEG noise reduction using the empirical mode decomposition(Section 16.5). Finally the chapter concludes with a discussion on other perspectives of using advanced (t,f) methods for medical diagnosis and prognosis in other areas of neurosciences (Section 16.6). Scopus
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- 2016
9. Advanced design and specifications of TFDs
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Flandrin, P., Williams, W.J., Baraniuk, R.G., Jones, D.L., Putland, G.R., Papandreou-Suppappola, A., Boashash, B., Xia, X.-G., Jawad, B.K., Khan, N.A., Sejdić, E., Assous, S., and Ventosa, S.
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symbols.namesake ,Polynomial ,Distribution (mathematics) ,Basis (linear algebra) ,Section (archaeology) ,Computer science ,Advanced designs ,Kernel (statistics) ,Gaussian function ,symbols ,Algorithm ,Energy (signal processing) ,Group delay and phase delay - Abstract
This chapter describes in detail specific examples of design of time-frequency distributions (TFDs), extending the material described in Chapters 2 and 3 and covering it in more depth and at a more advanced level. This key time-frequency (t, f) topic is covered in 11 sections with appropriate internal and external cross-referencing. Ambiguity functions (AFs) are traditionally used in radar and sonar. As dual of TFDs via a 2D Fourier transform (FT), they are a key basis for TFD kernel design methodologies (Section 5.1). One of the first TFDs constructed on this basis is the Gaussian kernel distribution, a TFD designed for its reduced interference properties (Section 5.2). To better adapt to the signal under analysis and achieve higher resolution and concentration performance, we can design adaptive TFDs using optimization theory (Section 5.3). TFDs can also be designed and adapted to a specific class of signals such as polynomial frequency modulated (FM) signals, leading to the formulation of polynomial Wigner-Ville distributions (WVDs) (Section 5.4). The design of such methods can be related mathematically to higher-order spectra (HOS) (Section 5.5). Another example of TFDs adapted to a particular class of signals is that of TFDs adapted to signals with dispersive group delay (Section 5.6). A step-by-step methodology for the design of a specific TFD is provided using separable kernels (Section 5.7). The class of generalized marginal TFDs is related to the fractional FT, allowing further design possibilities (Section 5.8). Section 5.9 discusses fixed kernel high-resolution TFDs that improve performance by accounting for directions of energy concentration of signal components in the (t, f) domain. Adaptive methods that estimate the direction of the smoothing kernel on a point-by-point basis are presented in Section 5.10. Section 5.11 uses linear (t, f) methods based on a modified version of the S-transform (ST) to estimate the phase synchrony. Finally, Section 5.12 reviews the requirements for designing positive TFDs.
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- 2016
10. Cognitive tasks and cerebral blood flow through anterior cerebral arteries: A study via functional transcranial Doppler ultrasound recordings
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Bleton, H, Perera, S, Sejdić, E, Bleton, H, Perera, S, and Sejdić, E
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Background: Functional transcanial Doppler ultrasound (fTCD) is a convenient approach to examine cerebral blood flow velocity (CBFV) in major cerebral arteries. Methods: In this study, the anterior cerebral artery (ACA) was insonated on both sides, that is, right ACA (R-ACA) and left ACA (L-ACA). The envelope signals (the maximum velocity) and the raw signals were analyzed during cognitive processes, i.e. word-generation tasks, geometric tasks and resting state periods separating each task. Data which were collected from 20 healthy participants were used to investigate the changes and the hemispheric functioning while performing cognitive tasks. Signal characteristics were analyzed in time domain, frequency domain and time-frequency domain. Results: Significant results have been obtained through the use of both classic/modern methods (i.e. envelope/raw, time and frequency/information-theoretic and time-frequency domains). The frequency features extracted from the raw signals highlighted sex effects on cerebral blood flow which revealed distinct brain response during each process and during resting periods. In the time-frequency analysis, the distribution of wavelet energies on the envelope signals moved around the low frequencies during mental processes and did not experience any lateralization during cognitive tasks. Conclusions: Even if no lateralization effects were noticed during resting-state, verbal and geometric tasks, understanding CBFV in ACA during cognitive tasks could complement information extracted from cerebral blood flow in middle cerebral arteries during similar cognitive tasks (i.e. sex effects).
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- 2016
11. A statistical analysis of cervical auscultation signals from adults with unsafe airway protection
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Dudik, JM, Kurosu, A, Coyle, JL, Sejdić, E, Dudik, JM, Kurosu, A, Coyle, JL, and Sejdić, E
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Background: Aspiration, where food or liquid is allowed to enter the larynx during a swallow, is recognized as the most clinically salient feature of oropharyngeal dysphagia. This event can lead to short-term harm via airway obstruction or more long-term effects such as pneumonia. In order to non-invasively identify this event using high resolution cervical auscultation there is a need to characterize cervical auscultation signals from subjects with dysphagia who aspirate. Methods: In this study, we collected swallowing sound and vibration data from 76 adults (50 men, 26 women, mean age 62) who underwent a routine videofluoroscopy swallowing examination. The analysis was limited to swallows of liquid with either thin (<5 cps) or viscous (≈300 cps) consistency and was divided into those with deep laryngeal penetration or aspiration (unsafe airway protection), and those with either shallow or no laryngeal penetration (safe airway protection), using a standardized scale. After calculating a selection of time, frequency, and time-frequency features for each swallow, the safe and unsafe categories were compared using Wilcoxon rank-sum statistical tests. Results: Our analysis found that few of our chosen features varied in magnitude between safe and unsafe swallows with thin swallows demonstrating no statistical variation. We also supported our past findings with regard to the effects of sex and the presence or absence of stroke on cervical ausculation signals, but noticed certain discrepancies with regards to bolus viscosity. Conclusions: Overall, our results support the necessity of using multiple statistical features concurrently to identify laryngeal penetration of swallowed boluses in future work with high resolution cervical auscultation.
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- 2016
12. A comparative analysis of swallowing accelerometry and sounds during saliva swallows
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Dudik, JM, Jestrović, I, Luan, B, Coyle, JL, Sejdić, E, Dudik, JM, Jestrović, I, Luan, B, Coyle, JL, and Sejdić, E
- Abstract
Background: Accelerometry (the measurement of vibrations) and auscultation (the measurement of sounds) are both non-invasive techniques that have been explored for their potential to detect abnormalities in swallowing. The differences between these techniques and the information they capture about swallowing have not previously been explored in a direct comparison. Methods: In this study, we investigated the differences between dual-axis swallowing accelerometry and swallowing sounds by recording data from adult participants and calculating a number of time and frequency domain features. During the experiment, 55 participants (ages 18-65) were asked to complete five saliva swallows in a neutral head position. The resulting data was processed using previously designed techniques including wavelet denoising, spline filtering, and fuzzy means segmentation. The pre-processed signals were then used to calculate 9 time, frequency, and time-frequency domain features for each independent signal. Wilcoxon signed-rank and Wilcoxon rank-sum tests were utilized to compare feature values across transducers and patient demographics, respectively. Results: In addition to finding a number of features that varied between male and female participants, our statistical analysis determined that the majority of our chosen features were statistically significantly different across the two sensor methods and that the dependence on within-subject factors varied with the transducer type. However, a regression analysis showed that age accounted for an insignificant amount of variation in our signals. Conclusions: We conclude that swallowing accelerometry and swallowing sounds provide different information about deglutition despite utilizing similar transduction methods. This contradicts past assumptions in the field and necessitates the development of separate analysis and processing techniques for swallowing sounds and vibrations.
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- 2015
13. Characterizing functional connectivity patterns during saliva swallows in different head positions
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Jestrović, I, Coyle, JL, Sejdić, E, Jestrović, I, Coyle, JL, and Sejdić, E
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Background: The anatomical rationale and efficacy of the chin tuck in improving airway protection for some people with swallowing disorders have been well researched and established. However, there are still open questions regarding whether brain activity for swallowing control is altered while performing this chin-tuck maneuver. Methods: In this study, we collected EEG signals from 55 healthy adults while swallowing in the neutral and chin-tuck head positions. The time-frequency based synchrony measure was used to form brain networks. We investigated both the small-world properties of these brain networks and differences among the constructed brain networks for the two head positions during swallowing tasks. Results: We showed that brain networks for swallowing in both head positions exhibit small-world properties. Furthermore, we showed that swallowing in the chin-tuck head position affects brain networks in the Alpha and Gamma frequency bands. Conclusions: According to these results, we can tell that the parameter of head position should be considered in future investigations which utilize EEG signals during swallowing activity.
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- 2015
14. Cognitive tasks during walking affect cerebral blood flow signal features in middle cerebral arteries and their correlation to gait characteristics
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Gatouillat, A, Bleton, H, VanSwearingen, J, Perera, S, Thompson, S, Smith, T, Sejdić, E, Gatouillat, A, Bleton, H, VanSwearingen, J, Perera, S, Thompson, S, Smith, T, and Sejdić, E
- Abstract
Gait is a complex process involving both cognitive and sensory ability and is strongly impacted by the environment. In this paper, we propose to study of the impact of a cognitive task during gait on the cerebral blood flow velocity, the blood flow signal features and the correlation of gait and blood flow features through a dual task methodology. Both cerebral blood flow velocity and gait characteristics of eleven participants with no history of brain or gait conditions were recorded using transcranial Doppler on mid-cerebral artery while on a treadmill. The cognitive task was induced by a backward counting starting from 10,000 with decrement of 7. Central blood flow velocity raw and envelope features were extracted in both time, frequency and time-scale domain; information-theoretic metrics were also extracted and statistical significances were inspected. A similar feature extraction was performed on the stride interval signal. Statistical differences between the cognitive and baseline trials, between the left and right mid-cerebral arteries signals and the impact of the antropometric variables where studied using linear mixed models. No statistical differences were found between the left and right mid-cerebral arteries flows or the baseline and cognitive state gait features, while statistical differences for specific features were measured between cognitive and baseline states. These statistical differences found between the baseline and cognitive states show that cognitive process has an impact on the cerebral activity during walking. The state was found to have an impact on the correlation between the gait and blood flow features.
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- 2015
15. Motor imagery of gait: A new way to detect mild cognitive impairment?
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Beauchet, O, Launay, CP, Sejdić, E, Allali, G, Annweiler, C, Beauchet, O, Launay, CP, Sejdić, E, Allali, G, and Annweiler, C
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Objectives. 1) To measure and compare the time required to perform (pTUG) and the time required to imagine (iTUG) the Timed Up & Go (TUG), and the time difference between these two tasks (i.e., TUG delta time) in older adults with cognitive decline (i.e., mild cognitive impairment (MCI) and mild-to-moderate Alzheimer disease and related disorders (ADRD)) and in cognitively healthy individuals (CHI); and 2) to examine any association between the TUG delta time and a cognitive status. Methods. Sixty-six participants (24 CHI, 23 individuals with MCI, and 19 individuals with ADRD) were recruited in this cross-sectional study. The mean and standard deviation of the pTUG and iTUG completion times and the TUG delta time, as well as age, gender, and Mini-Mental State Examination (MMSE) scores were used as outcomes. Participants were separated into three groups based on the tertilization of TUG delta time: lowest (<13.6%; n = 22; best performance), intermediate (13.6-52.2%; n = 22), and highest tertile (>52.2%; n = 22, worst performance). Results: Fewer CHI were in the group exhibiting the highest tertile of TUG delta time compared to individuals with lowest and intermediate TUG delta times (p = 0.013). Being in the highest tertile of the TUG delta time was associated with cognitive decline in the unadjusted model (p = 0.012 for MCI, and p = 0.021 for mild-to-moderate ADRD). In the multivariate models, this association remained significant only for individuals with MCI (p = 0.019 while adjusting for age and gender; p = 0.047 while adjusting for age, gender, and MMSE score; p = 0.012 for the stepwise backward model). Conclusions: Our results provide the first evidence that motor imagery of gait may be used as a biomarker of MCI in older adults. © 2014 Beauchet et al.; licensee BioMed Central Ltd.
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- 2014
16. Motor phenotype of decline in cognitive performance among community-dwellers without dementia: Population-based study and meta-analysis
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Beauchet, O, Allali, G, Montero-Odasso, M, Sejdić, E, Fantino, B, Annweiler, C, Beauchet, O, Allali, G, Montero-Odasso, M, Sejdić, E, Fantino, B, and Annweiler, C
- Abstract
Background: Decline in cognitive performance is associated with gait deterioration. Our objectives were: 1) to determine, from an original study in older community-dwellers without diagnosis of dementia, which gait parameters, among slower gait speed, higher stride time variability (STV) and Timed Up & Go test (TUG) delta time, were most strongly associated with lower performance in two cognitive domains (i.e., episodic memory and executive function); and 2) to quantitatively synthesize, with a systematic review and meta-analysis, the association between gait performance and cognitive decline (i.e., mild cognitive impairment (MCI) and dementia). Methods: Based on a cross-sectional design, 934 older community-dwellers without dementia (mean6standard deviation, 70.3 64.9years; 52.1% female) were recruited. A score at 5 on the Short Mini-Mental State Examination defined low episodic memory performance. Low executive performance was defined by clock-drawing test errors. STV and gait speed were measured using GAITRite system. TUG delta time was calculated as the difference between the times needed to perform and to imagine the TUG. Then, a systematic Medline search was conducted in November 2013 using the Medical Subject Heading terms "Delirium," "Dementia," "Amnestic," "Cognitive disorders" combined with "Gait" OR "Gait disorders, Neurologic" and "Variability." Findings: A total of 294 (31.5%) participants presented decline in cognitive performance. Higher STV, higher TUG delta time, and slower gait speed were associated with decline in episodic memory and executive performances (all P-values <0.001). The highest magnitude of association was found for higher STV (effect size = -0.74 [95% Confidence Interval (CI): -1.05;- 0.43], among participants combining of decline in episodic memory and in executive performances). Meta-analysis underscored that higher STV represented a gait biomarker in patients with MCI (effect size = 0.48 [95% CI: 0.30;0.65]) and dementia (effect s
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- 2014
17. The effects of increased fluid viscosity on stationary characteristics of EEG signal in healthy adults
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Jestrović, I., primary, Coyle, J.L., additional, and Sejdić, E., additional
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- 2014
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18. The effects of increased fluid viscosity on swallowing sounds in healthy adults
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Jestrović, I, Dudik, JM, Luan, B, Coyle, JL, Sejdić, E, Jestrović, I, Dudik, JM, Luan, B, Coyle, JL, and Sejdić, E
- Abstract
Background: Cervical auscultation (CA) is an affordable, non-invasive technique used to observe sounds occurring during swallowing. CA involves swallowing characterization via stethoscopes or microphones, while accelerometers can detect other vibratory signals. While the effects of fluid viscosity on swallowing accelerometry signals is well understood, there are still open questions about these effects on swallowing sounds. Therefore, this study investigated the influence of fluids with increasing thickness on swallowing sound characteristics.Method: We collected swallowing sounds and swallowing accelerometry signals from 56 healthy participants. Each participant completed five water swallows, five swallows of nectar-thick apple juice, and five swallows of honey-thick apple juice. These swallows were completed in neutral head and chin-tuck head positions. After pre-processing of collected signals, a number of features in time, frequency and time-frequency domains were extracted.Results: Our numerical analysis demonstrated that significant influence of viscosity was found in most of the features. In general, features extracted from swallows in the neutral head position were affected more than swallows from the chin-tuck position. Furthermore, most of the differences were found between water and fluids with higher viscosity. Almost no significant differences were found between swallows involving nectar-thick and honey-thick apple juices. Our results also showed that thicker fluids had higher acoustic regularity and predictability as demonstrated by the information-theoretic features, and a lower frequency content as demonstrated by features in the frequency domain.Conclusions: According to these results, we can conclude that viscosity of fluids should be considered in future investigations involving swallowing sounds. © 2013 Jestrovićet al.; licensee BioMed Central Ltd.
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- 2013
19. A Study of Brain Networks Associated with Swallowing Using Graph-Theoretical Approaches
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Luan, B, Sörös, P, Sejdić, E, Luan, B, Sörös, P, and Sejdić, E
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Functional connectivity between brain regions during swallowing tasks is still not well understood. Understanding these complex interactions is of great interest from both a scientific and a clinical perspective. In this study, functional magnetic resonance imaging (fMRI) was utilized to study brain functional networks during voluntary saliva swallowing in twenty-two adult healthy subjects (all females, 23.1±1.52 years of age). To construct these functional connections, we computed mean partial correlation matrices over ninety brain regions for each participant. Two regions were determined to be functionally connected if their correlation was above a certain threshold. These correlation matrices were then analyzed using graph-theoretical approaches. In particular, we considered several network measures for the whole brain and for swallowing-related brain regions. The results have shown that significant pairwise functional connections were, mostly, either local and intra-hemispheric or symmetrically inter-hemispheric. Furthermore, we showed that all human brain functional network, although varying in some degree, had typical small-world properties as compared to regular networks and random networks. These properties allow information transfer within the network at a relatively high efficiency. Swallowing-related brain regions also had higher values for some of the network measures in comparison to when these measures were calculated for the whole brain. The current results warrant further investigation of graph-theoretical approaches as a potential tool for understanding the neural basis of dysphagia. © 2013 Luan et al.
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- 2013
20. An Analysis of Resting-State Functional Transcranial Doppler Recordings from Middle Cerebral Arteries
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Sejdić, E, Kalika, D, Czarnek, N, Sejdić, E, Kalika, D, and Czarnek, N
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Functional transcrannial Doppler (fTCD) is used for monitoring the hemodynamics characteristics of major cerebral arteries. Its resting-state characteristics are known only when considering the maximal velocity corresponding to the highest Doppler shift (so called the envelope signals). Significantly more information about the resting-state fTCD can be gained when considering the raw cerebral blood flow velocity (CBFV) recordings. In this paper, we considered simultaneously acquired envelope and raw CBFV signals. Specifically, we collected bilateral CBFV recordings from left and right middle cerebral arteries using 20 healthy subjects (10 females). The data collection lasted for 15 minutes. The subjects were asked to remain awake, stay silent, and try to remain thought-free during the data collection. Time, frequency and time-frequency features were extracted from both the raw and the envelope CBFV signals. The effects of age, sex and body-mass index were examined on the extracted features. The results showed that the raw CBFV signals had a higher frequency content, and its temporal structures were almost uncorrelated. The information-theoretic features showed that the raw recordings from left and right middle cerebral arteries had higher content of mutual information than the envelope signals. Age and body-mass index did not have statistically significant effects on the extracted features. Sex-based differences were observed in all three domains and for both, the envelope signals and the raw CBFV signals. These findings indicate that the raw CBFV signals provide valuable information about the cerebral blood flow which can be utilized in further validation of fTCD as a clinical tool. © 2013 Sejdić et al.
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- 2013
21. A method for removal of low frequency components associated with head movements from dual-axis swallowing accelerometry signals
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Sejdić, E, Steele, CM, Chau, T, Sejdić, E, Steele, CM, and Chau, T
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Head movements can greatly affect swallowing accelerometry signals. In this paper, we implement a spline-based approach to remove low frequency components associated with these motions. Our approach was tested using both synthetic and real data. Synthetic signals were used to perform a comparative analysis of the spline-based approach with other similar techniques. Real data, obtained data from 408 healthy participants during various swallowing tasks, was used to analyze the processing accuracy with and without the spline-based head motions removal scheme. Specifically, we analyzed the segmentation accuracy and the effects of the scheme on statistical properties of these signals, as measured by the scaling analysis. The results of the numerical analysis showed that the spline-based technique achieves a superior performance in comparison to other existing techniques. Additionally, when applied to real data, we improved the accuracy of the segmentation process by achieving a 27% drop in the number of false negatives and a 30% drop in the number of false positives. Furthermore, the anthropometric trends in the statistical properties of these signals remained unaltered as shown by the scaling analysis, but the strength of statistical persistence was significantly reduced. These results clearly indicate that any future medical devices based on swallowing accelerometry signals should remove head motions from these signals in order to increase segmentation accuracy. © 2012 Sejdić et al.
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- 2012
22. The effects of rhythmic sensory cues on the temporal dynamics of human gait
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Sejdić, E, Fu, Y, Pak, A, Fairley, JA, Chau, T, Sejdić, E, Fu, Y, Pak, A, Fairley, JA, and Chau, T
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Walking is a complex, rhythmic task performed by the locomotor system. However, natural gait rhythms can be influenced by metronomic auditory stimuli, a phenomenon of particular interest in neurological rehabilitation. In this paper, we examined the effects of aural, visual and tactile rhythmic cues on the temporal dynamics associated with human gait. Data were collected from fifteen healthy adults in two sessions. Each session consisted of five 15-minute trials. In the first trial of each session, participants walked at their preferred walking speed. In subsequent trials, participants were asked to walk to a metronomic beat, provided through visually, aurally, tactile or all three cues (simultaneously and in sync), the pace of which was set to the preferred walking speed of the first trial. Using the collected data, we extracted several parameters including: gait speed, mean stride interval, stride interval variability, scaling exponent and maximum Lyapunov exponent. The extracted parameters showed that rhythmic sensory cues affect the temporal dynamics of human gait. The auditory rhythmic cue had the greatest influence on the gait parameters, while the visual cue had no statistically significant effect on the scaling exponent. These results demonstrate that visual rhythmic cues could be considered as an alternative cueing modality in rehabilitation without concern of adversely altering the statistical persistence of walking. © 2012 Sejdić et al.
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- 2012
23. A brain-computer interface based on bilateral transcranial Doppler ultrasound
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Myrden, AJB, Kushki, A, Sejdić, E, Guerguerian, AM, Chau, T, Myrden, AJB, Kushki, A, Sejdić, E, Guerguerian, AM, and Chau, T
- Abstract
In this study, we investigate the feasibility of a BCI based on transcranial Doppler ultrasound (TCD), a medical imaging technique used to monitor cerebral blood flow velocity. We classified the cerebral blood flow velocity changes associated with two mental tasks - a word generation task, and a mental rotation task. Cerebral blood flow velocity was measured simultaneously within the left and right middle cerebral arteries while nine able-bodied adults alternated between mental activity (i.e. word generation or mental rotation) and relaxation. Using linear discriminant analysis and a set of time-domain features, word generation and mental rotation were classified with respective average accuracies of 82.9%and 10.0 across all participants. Accuracies for all participants significantly exceeded chance. These results indicate that TCD is a promising measurement modality for BCI research. © 2011 Myrden et al.
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- 2011
24. Fractional Fourier transform as a signal processing tool: An overview of recent developments
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Sejdić, E, Djurović, I, Stanković, L, Sejdić, E, Djurović, I, and Stanković, L
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Fractional Fourier transform (FRFT) is a generalization of the Fourier transform, rediscovered many times over the past 100 years. In this paper, we provide an overview of recent contributions pertaining to the FRFT. Specifically, the paper is geared toward signal processing practitioners by emphasizing the practical digital realizations and applications of the FRFT. It discusses three major topics. First, the manuscripts relates the FRFT to other mathematical transforms. Second, it discusses various approaches for practical realizations of the FRFT. Third, we overview the practical applications of the FRFT. From these discussions, we can clearly state that the FRFT is closely related to other mathematical transforms, such as timefrequency and linear canonical transforms. Nevertheless, we still feel that major contributions are expected in the field of the digital realizations and its applications, especially, since many digital realizations of the FRFT still lack properties of the continuous FRFT. Overall, the FRFT is a valuable signal processing tool. Its practical applications are expected to grow significantly in years to come, given that the FRFT offers many advantages over the traditional Fourier analysis. © 2010 Elsevier B.V. All rights reserved.
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- 2011
25. Robust S-transform based on L-DFT
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Sejdić, E, Djurović, I, Sejdić, E, and Djurović, I
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Time-frequency representations of signals obtained by the S-transform can be very sensitive to the presence of α- stable noise. An algorithm for the robust S-transform is introduced. The proposed scheme is based on the L-DFT. The results of conducted numerical analysis show a significantly enhanced performance of the proposed scheme compared to the standard S-transform. © 2010 The Institution of Engineering and Technology.
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- 2010
26. Measures of dynamic stability: Detecting differences between walking overground and on a compliant surface
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Chang, MD, Sejdić, E, Wright, V, Chau, T, Chang, MD, Sejdić, E, Wright, V, and Chau, T
- Abstract
Numerous measures of dynamic stability have been proposed to gauge fall risk in the elderly, including stride interval variability and variability of the center of mass. However, these measures have been deemed inadequate because they do not take into account temporal information. Therefore, research on the measurement of dynamic stability has turned to other analysis methods such as stride interval dynamics and the maximum Lyapunov exponent. Stride interval dynamics reflect the statistical persistence of an individual's stride interval time series and the Lyapunov exponent quantifies local dynamic stability - the sensitivity of the system to infinitesimal perturbations. In this study, we compare the ability of these measurement tools to detect changes between overground and compliant-surface walking, a condition known to affect stability, to determine their aptness as measures of dynamic stability. Fourteen able-bodied participants completed three 15 min walks, two overground and one on a compliant surface. Our results show that the Lyapunov exponent may be more sensitive to gait changes than stride interval dynamics and gait variability measures. © 2010 Elsevier B.V.
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- 2010
27. Baseline characteristics of dual-axis cervical accelerometry signals
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Sejdić, E, Komisar, V, Steele, CM, Chau, T, Sejdić, E, Komisar, V, Steele, CM, and Chau, T
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Dual-axis swallowing accelerometry is a promising noninvasive tool for the assessment of difficulties during deglutition. The resting and anaerobic characteristics of these signals, however, are still unknown. This paper presents a study of baseline characteristics (stationarity, spectral features, and information content) of dual-axis cervical vibrations. In addition, modeling of a data acquisition system was performed to annul any undesired instrumentation effects. Two independent data collection procedures were conducted to fulfil the goals of the study. For baseline characterization, data were acquired from 50 healthy adult subjects. To model the data acquisition (DAQ) system, ten recordings were obtained while the system was exposed to random small vibrations. The inverse filtering approach removed extraneous effects introduced by the DAQ system. Approximately half of the filtered signals were stationary in nature. All signals exhibited a level of statistical dependence between the two axes. Also, there were very low frequency oscillations present in these signals that may be attributable to vasomotion of blood vessels near the thyroid cartilage, blood flow, and respiration. Demographic variables such as age and gender did not statistically influence baseline information-theoretic signal characteristics. However, participant age did affect the baseline spectral characteristics. These findings are important to the further development of diagnostic devices based on dual-axis swallowing vibration signals. © 2010 Biomedical Engineering Society.
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- 2010
28. Variability in Execution of the Chin-Down Maneuver by Healthy Adults
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Steele, C.M., primary, Hung, D., additional, Sejdić, E., additional, Chau, T., additional, and Fraser, S., additional
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- 2010
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29. Robust S-transform based on L-DFT
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Sejdić, E., primary and Djurović, I., additional
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- 2010
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30. Spinal cord injury models in non human primates: Are lesions created by sharp instruments relevant to human injuries?
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Sledge, J., Andrew Graham, W., Westmoreland, S., Sejdic, E., Miller, A., Hoggatt, A., and Nesathurai, S.
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- 2013
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31. An algorithm for decomposition of heart sounds based on s-method
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Sejdić, E., Raković, P., Daković, M., and Ljubiša Stanković
- Abstract
Publication in the conference proceedings of EUSIPCO, Poznan, Poland, 2007
32. Quantitative classification of pediatric swallowing through accelerometry
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Celeste Merey, Azadeh Kushki, Sejdić Ervin, Berall Glenn, and Chau Tom
- Subjects
Swallowing ,Dysphagia ,Dual-axis ,Accelerometry ,Classification ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Abstract Background Dysphagia or swallowing disorder negatively impacts a child’s health and development. The gold standard of dysphagia detection is videofluoroscopy which exposes the child to ionizing radiation, and requires specialized clinical expertise and expensive institutionally-based equipment, precluding day-to-day and repeated assessment of fluctuating swallowing function. Swallowing accelerometry is the non-invasive measurement of cervical vibrations during swallowing and may provide a portable and cost-effective bedside alternative. In particular, dual-axis swallowing accelerometry has demonstrated screening potential in older persons with neurogenic dysphagia, but the technique has not been evaluated in the pediatric population. Methods In this study, dual-axis accelerometric signals were collected simultaneous to videofluoroscopic records from 29 pediatric participants (age 6.8 ± 4.8 years; 20 males) previously diagnosed with neurogenic dysphagia. Participants swallowed 3-5 sips of barium-coated boluses of different consistencies (normally, from thick puree to thin liquid) by spoon or bottle. Videofluoroscopic records were reviewed retrospectively by a clinical expert to extract swallow timings and ratings. The dual-axis acceleration signals corresponding to each identified swallow were pre-processed, segmented and trimmed prior to feature extraction from time, frequency, time-frequency and information theoretic domains. Feature space dimensionality was reduced via principal components. Results Using 8-fold cross-validation, 16-17 dimensions and a support vector machine classifier with an RBF kernel, an adjusted accuracy of 89.6% ± 0.9 was achieved for the discrimination between swallows with and with out airway entry. Conclusions Our results suggest that dual-axis accelerometry has merit in the non-invasive detection of unsafe swallows in children and deserves further consideration as a pediatric medical device.
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- 2012
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33. Automatic discrimination between safe and unsafe swallowing using a reputation-based classifier
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Nikjoo Mohammad S, Steele Catriona M, Sejdić Ervin, and Chau Tom
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Medical technology ,R855-855.5 - Abstract
Abstract Background Swallowing accelerometry has been suggested as a potential non-invasive tool for bedside dysphagia screening. Various vibratory signal features and complementary measurement modalities have been put forth in the literature for the potential discrimination between safe and unsafe swallowing. To date, automatic classification of swallowing accelerometry has exclusively involved a single-axis of vibration although a second axis is known to contain additional information about the nature of the swallow. Furthermore, the only published attempt at automatic classification in adult patients has been based on a small sample of swallowing vibrations. Methods In this paper, a large corpus of dual-axis accelerometric signals were collected from 30 older adults (aged 65.47 ± 13.4 years, 15 male) referred to videofluoroscopic examination on the suspicion of dysphagia. We invoked a reputation-based classifier combination to automatically categorize the dual-axis accelerometric signals into safe and unsafe swallows, as labeled via videofluoroscopic review. From these participants, a total of 224 swallowing samples were obtained, 164 of which were labeled as unsafe swallows (swallows where the bolus entered the airway) and 60 as safe swallows. Three separate support vector machine (SVM) classifiers and eight different features were selected for classification. Results With selected time, frequency and information theoretic features, the reputation-based algorithm distinguished between safe and unsafe swallowing with promising accuracy (80.48 ± 5.0%), high sensitivity (97.1 ± 2%) and modest specificity (64 ± 8.8%). Interpretation of the most discriminatory features revealed that in general, unsafe swallows had lower mean vibration amplitude and faster autocorrelation decay, suggestive of decreased hyoid excursion and compromised coordination, respectively. Further, owing to its performance-based weighting of component classifiers, the static reputation-based algorithm outperformed the democratic majority voting algorithm on this clinical data set. Conclusion Given its computational efficiency and high sensitivity, reputation-based classification of dual-axis accelerometry ought to be considered in future developments of a point-of-care swallow assessment where clinical informatics are desired.
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- 2011
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34. The effects of head movement on dual-axis cervical accelerometry signals
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Sejdić Ervin, Steele Catriona M, and Chau Tom
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Medicine ,Biology (General) ,QH301-705.5 ,Science (General) ,Q1-390 - Abstract
Abstract Background Head motions can severely affect dual-axis cervical acceloremetry signals. A complete understanding of the effects of head motion is required before a robust accelerometry-based medical device can be developed. In this paper, we examine the spectral characteristics of dual-axis cervical accelerometry signals in the absence of swallowing but in the presence of head motions. Findings Data from 50 healthy adults were collected while participants performed five different head motions. Three different spectral features were extracted from each recording: peak frequency, spectral centroid and bandwidth. Statistical analyses showed that peak frequencies are independent of the type of head motion, participant gender and age. However, spectral centroids are statistically different between the anterior-posterior (A-P) and superior-inferior (S-I) directions and between different motion. Additionally, statistically different bandwidths are observed for head tilts down and back between the A-P and the S-I directions. Conclusions These differences indicate that head motions induce additional non-dominant spectral components in dual-axis cervical recordings. The results presented here suggest that head motion ought to be considered in the development of medical devices based on dual-axis cervical accelerometery signals.
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- 2010
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35. The effect of accelerometer location on the classification of single-site forearm mechanomyograms
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Sejdić Ervin, Alves Natasha, Sahota Bhupinder, and Chau Tom
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Medical technology ,R855-855.5 - Abstract
Abstract Background Recently, pattern recognition methods have been deployed in the classification of multiple activation states from mechanomyogram (MMG) signals for the purpose of controlling switching interfaces. Given the propagative properties of MMG signals, it has been suggested that MMG classification should be robust to changes in sensor placement. Nonetheless, this purported robustness remains speculative to date. This study sought to quantify the change in classification accuracy, if any, when a classifier trained with MMG signals from the muscle belly, is subsequently tested with MMG signals from a nearby location. Methods An arrangement of 5 accelerometers was attached to the flexor carpi radialis muscle of 12 able-bodied participants; a reference accelerometer was located over the muscle belly, two peripheral accelerometers were positioned along the muscle's transverse axis and two more were aligned to the muscle's longitudinal axis. Participants performed three classes of muscle activity: wrist flexion, wrist extension and semi-pronation. A collection of time, frequency and time-frequency features were considered and reduced by genetic feature selection. The classifier, trained using features from the reference accelerometer, was tested with signals from the longitudinally and transversally displaced accelerometers. Results Classification degradation due to accelerometer displacement was significant for all participants, and showed no consistent trend with the direction of displacement. Further, the displaced accelerometer signals showed task-dependent de-correlations with respect to the reference accelerometer. Conclusions These results indicate that MMG signal features vary with spatial location and that accelerometer displacements of only 1-2 cm cause sufficient feature drift to significantly diminish classification accuracy. This finding emphasizes the importance of consistent sensor placement between MMG classifier training and deployment for accurate control of switching interfaces.
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- 2010
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36. Effects of liquid stimuli on dual-axis swallowing accelerometry signals in a healthy population
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Sejdić Ervin, Lee Joon, Steele Catriona M, and Chau Tom
- Subjects
Medical technology ,R855-855.5 - Abstract
Abstract Background Dual-axis swallowing accelerometry has recently been proposed as a tool for non-invasive analysis of swallowing function. Although swallowing is known to be physiologically modifiable by the type of food or liquid (i.e., stimuli), the effects of stimuli on dual-axis accelerometry signals have never been thoroughly investigated. Thus, the objective of this study was to investigate stimulus effects on dual-axis accelerometry signal characteristics. Signals were acquired from 17 healthy participants while swallowing 4 different stimuli: water, nectar-thick and honey-thick apple juices, and a thin-liquid barium suspension. Two swallowing tasks were examined: discrete and sequential. A variety of features were extracted in the time and time-frequency domains after swallow segmentation and pre-processing. A separate Friedman test was conducted for each feature and for each swallowing task. Results Significant main stimulus effects were found on 6 out of 30 features for the discrete task and on 5 out of 30 features for the sequential task. Analysis of the features with significant stimulus effects suggested that the changes in the signals revealed slower and more pronounced swallowing patterns with increasing bolus viscosity. Conclusions We conclude that stimulus type does affect specific characteristics of dual-axis swallowing accelerometry signals, suggesting that associated clinical screening protocols may need to be stimulus specific.
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- 2010
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37. Investigating the correlation between paediatric stride interval persistence and gross energy expenditure
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Sejdić Ervin, Fairley Jillian A, and Chau Tom
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Medicine ,Biology (General) ,QH301-705.5 ,Science (General) ,Q1-390 - Abstract
Abstract Background Stride interval persistence, a term used to describe the correlation structure of stride interval time series, is thought to provide insight into neuromotor control, though its exact clinical meaning has not yet been realized. Since human locomotion is shaped by energy efficient movements, it has been hypothesized that stride interval dynamics and energy expenditure may be inherently tied, both having demonstrated similar sensitivities to age, disease, and pace-constrained walking. Findings This study tested for correlations between stride interval persistence and measures of energy expenditure including mass-specific gross oxygen consumption per minute (), mass-specific gross oxygen cost per meter (VO2) and heart rate (HR). Metabolic and stride interval data were collected from 30 asymptomatic children who completed one 10-minute walking trial under each of the following conditions: (i) overground walking, (ii) hands-free treadmill walking, and (iii) handrail-supported treadmill walking. Stride interval persistence was not significantly correlated with (p > 0.32), VO2 (p > 0.18) or HR (p > 0.56). Conclusions No simple linear dependence exists between stride interval persistence and measures of gross energy expenditure in asymptomatic children when walking overground and on a treadmill.
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- 2010
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38. A cardiorespiratory classifier of voluntary and involuntary electrodermal activity
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Sejdic Ervin, Power Sarah D, Blain Stefanie, Mihailidis Alex, and Chau Tom
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Medical technology ,R855-855.5 - Abstract
Abstract Background Electrodermal reactions (EDRs) can be attributed to many origins, including spontaneous fluctuations of electrodermal activity (EDA) and stimuli such as deep inspirations, voluntary mental activity and startling events. In fields that use EDA as a measure of psychophysiological state, the fact that EDRs may be elicited from many different stimuli is often ignored. This study attempts to classify observed EDRs as voluntary (i.e., generated from intentional respiratory or mental activity) or involuntary (i.e., generated from startling events or spontaneous electrodermal fluctuations). Methods Eight able-bodied participants were subjected to conditions that would cause a change in EDA: music imagery, startling noises, and deep inspirations. A user-centered cardiorespiratory classifier consisting of 1) an EDR detector, 2) a respiratory filter and 3) a cardiorespiratory filter was developed to automatically detect a participant's EDRs and to classify the origin of their stimulation as voluntary or involuntary. Results Detected EDRs were classified with a positive predictive value of 78%, a negative predictive value of 81% and an overall accuracy of 78%. Without the classifier, EDRs could only be correctly attributed as voluntary or involuntary with an accuracy of 50%. Conclusions The proposed classifier may enable investigators to form more accurate interpretations of electrodermal activity as a measure of an individual's psychophysiological state.
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- 2010
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39. Time-Frequency Analysis and Hermite Projection Method Applied to Swallowing Accelerometry Signals
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Chau Tom, Sejdić Ervin, Steele CatrionaM, Orović Irena, and Stanković Srdjan
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Telecommunication ,TK5101-6720 ,Electronics ,TK7800-8360 - Abstract
Fast Hermite projections have been often used in image-processing procedures such as image database retrieval, projection filtering, and texture analysis. In this paper, we propose an innovative approach for the analysis of one-dimensional biomedical signals that combines the Hermite projection method with time-frequency analysis. In particular, we propose a two-step approach to characterize vibrations of various origins in swallowing accelerometry signals. First, by using time-frequency analysis we obtain the energy distribution of signal frequency content in time. Second, by using fast Hermite projections we characterize whether the analyzed time-frequency regions are associated with swallowing or other phenomena (vocalization, noise, bursts, etc.). The numerical analysis of the proposed scheme clearly shows that by using a few Hermite functions, vibrations of various origins are distinguishable. These results will be the basis for further analysis of swallowing accelerometry to detect swallowing difficulties.
- Published
- 2010
40. Extraction of average neck flexion angle during swallowing in neutral and chin-tuck positions
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Sejdić Ervin, Hung Delbert, Steele Catriona M, and Chau Tom
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Medical technology ,R855-855.5 - Abstract
Abstract Background A common but debated technique in the management of swallowing difficulties is the chin tuck swallow, where the neck is flexed forward prior to swallowing. Natural variations in chin tuck angles across individuals may contribute to the differential effectiveness of the technique. Methodology To facilitate the study of chin tuck angle variations, we present a template tracking algorithm that automatically extracts neck angles from sagittal videos of individuals performing chin tuck swallows. Three yellow markers geometrically arranged on a pair of dark visors were used as tracking cues. Results The algorithm was applied to data collected from 178 healthy participants during neutral and chin tuck position swallows. Our analyses revealed no major influences of body mass index and age on neck flexion angles during swallowing, while gender influenced the average neck angle only during wet swallows in the neutral position. Chin tuck angles seem to be independent of anthropometry and gender in healthy adults, but deserve further study in pathological populations. Conclusion The proposed neck flexion angle extraction algorithm may be useful in future studies where strict participant compliance to swallowing task protocol can be assured.
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- 2009
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41. Assessing the Performance of Models from the 2022 RSNA Cervical Spine Fracture Detection Competition at a Level I Trauma Center.
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Hu Z, Patel M, Ball RL, Lin HM, Prevedello LM, Naseri M, Mathur S, Moreland R, Wilson J, Witiw C, Yeom KW, Ha Q, Hanley D, Seferbekov S, Chen H, Singer P, Henkel C, Pfeiffer P, Pan I, Sheoran H, Li W, Flanders AE, Kitamura FC, Richards T, Talbott J, Sejdić E, and Colak E
- Abstract
"Just Accepted" papers have undergone full peer review and have been accepted for publication in Radiology: Artificial Intelligence . This article will undergo copyediting, layout, and proof review before it is published in its final version. Please note that during production of the final copyedited article, errors may be discovered which could affect the content. Purpose To evaluate the performance of the top models from the RSNA 2022 Cervical Spine Fracture Detection challenge on a clinical test dataset of both noncontrast and contrast-enhanced CT scans acquired at a level I trauma center. Materials and Methods Seven top-performing models in the RSNA 2022 Cervical Spine Fracture Detection challenge were retrospectively evaluated on a clinical test set of 1,828 CT scans (1,829 series: 130 positive for fracture, 1,699 negative for fracture; 1,308 noncontrast, 521 contrast-enhanced) from 1,779 patients (mean age, 55.8 ± 22.1 years; 1,154 male). Scans were acquired without exclusion criteria over one year (January to December 2022) from the emergency department of a neurosurgical and level I trauma center. Model performance was assessed using area under the receiver operating characteristic curve (AUC), sensitivity, and specificity. False positive and false negative cases were further analyzed by a neuroradiologist. Results Although all 7 models showed decreased performance on the clinical test set compared with the challenge dataset, the models maintained high performances. On noncontrast CT scans, the models achieved a mean AUC of 0.89 (range: 0.81-0.92), sensitivity of 67.0% (range: 30.9%-80.0%), and specificity of 92.9% (range: 82.1%-99.0%). On contrast-enhanced CT scans, the models had a mean AUC of 0.88 (range: 0.76-0.94), sensitivity of 81.9% (range: 42.7%-100.0%), and specificity of 72.1% (range: 16.4%-92.8%). The models identified 10 fractures missed by radiologists. False-positives were more common in contrast-enhanced scans and observed in patients with degenerative changes on noncontrast scans, while false-negatives were often associated with degenerative changes and osteopenia. Conclusion The winning models from the 2022 RSNA AI Challenge demonstrated a high performance for cervical spine fracture detection on a clinical test dataset, warranting further evaluation for their use as clinical support tools. ©RSNA, 2024.
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- 2024
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42. Automatic Tracking of Hyoid Bone Displacement and Rotation Relative to Cervical Vertebrae in Videofluoroscopic Swallow Studies Using Deep Learning.
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Li W, Mao S, Mahoney AS, Coyle JL, and Sejdić E
- Subjects
- Humans, Fluoroscopy methods, Male, Video Recording methods, Female, Adult, Middle Aged, Biomechanical Phenomena physiology, Rotation, Aged, Image Processing, Computer-Assisted methods, Hyoid Bone diagnostic imaging, Hyoid Bone physiology, Deep Learning, Deglutition physiology, Cervical Vertebrae diagnostic imaging, Cervical Vertebrae physiology
- Abstract
The hyoid bone displacement and rotation are critical kinematic events of the swallowing process in the assessment of videofluoroscopic swallow studies (VFSS). However, the quantitative analysis of such events requires frame-by-frame manual annotation, which is labor-intensive and time-consuming. Our work aims to develop a method of automatically tracking hyoid bone displacement and rotation in VFSS. We proposed a full high-resolution network, a deep learning architecture, to detect the anterior and posterior of the hyoid bone to identify its location and rotation. Meanwhile, the anterior-inferior corners of the C2 and C4 vertebrae were detected simultaneously to automatically establish a new coordinate system and eliminate the effect of posture change. The proposed model was developed by 59,468 VFSS frames collected from 1488 swallowing samples, and it achieved an average landmark localization error of 2.38 pixels (around 0.5% of the image with 448 × 448 pixels) and an average angle prediction error of 0.065 radians in predicting C2-C4 and hyoid bone angles. In addition, the displacement of the hyoid bone center was automatically tracked on a frame-by-frame analysis, achieving an average mean absolute error of 2.22 pixels and 2.78 pixels in the x-axis and y-axis, respectively. The results of this study support the effectiveness and accuracy of the proposed method in detecting hyoid bone displacement and rotation. Our study provided an automatic method of analyzing hyoid bone kinematics during VFSS, which could contribute to early diagnosis and effective disease management., (© 2024. The Author(s) under exclusive licence to Society for Imaging Informatics in Medicine.)
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- 2024
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43. Machine Learning Classification of Body Part, Imaging Axis, and Intravenous Contrast Enhancement on CT Imaging.
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Li W, Lin HM, Lin A, Napoleone M, Moreland R, Murari A, Stepanov M, Ivanov E, Prasad AS, Shih G, Hu Z, Zulbayar S, Sejdić E, and Colak E
- Subjects
- Male, Humans, Female, Middle Aged, Retrospective Studies, Human Body, Machine Learning, Tomography, X-Ray Computed methods, Contrast Media, Deep Learning
- Abstract
Purpose: The development and evaluation of machine learning models that automatically identify the body part(s) imaged, axis of imaging, and the presence of intravenous contrast material of a CT series of images. Methods: This retrospective study included 6955 series from 1198 studies (501 female, 697 males, mean age 56.5 years) obtained between January 2010 and September 2021. Each series was annotated by a trained board-certified radiologist with labels consisting of 16 body parts, 3 imaging axes, and whether an intravenous contrast agent was used. The studies were randomly assigned to the training, validation and testing sets with a proportion of 70%, 20% and 10%, respectively, to develop a 3D deep neural network for each classification task. External validation was conducted with a total of 35,272 series from 7 publicly available datasets. The classification accuracy for each series was independently assessed for each task to evaluate model performance. Results: The accuracies for identifying the body parts, imaging axes, and the presence of intravenous contrast were 96.0% (95% CI: 94.6%, 97.2%), 99.2% (95% CI: 98.5%, 99.7%), and 97.5% (95% CI: 96.4%, 98.5%) respectively. The generalizability of the models was demonstrated through external validation with accuracies of 89.7 - 97.8%, 98.6 - 100%, and 87.8 - 98.6% for the same tasks. Conclusions: The developed models demonstrated high performance on both internal and external testing in identifying key aspects of a CT series., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
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- 2024
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44. Uneven surface and cognitive dual-task independently affect gait quality in older adults.
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Suri A, VanSwearingen J, Rosano C, Brach JS, Redfern MS, Sejdić E, and Rosso AL
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- Female, Humans, Aged, Aged, 80 and over, Male, Walking Speed, Cognition, Executive Function, Gait, Walking psychology
- Abstract
Background: Real-world mobility involves walking in challenging conditions. Assessing gait during simultaneous physical and cognitive challenges provides insights on cognitive health., Research Question: How does uneven surface, cognitive task, and their combination affect gait quality and does this gait performance relate to cognitive functioning?, Methods: Community-dwelling older adults (N = 104, age=75 ± 6 years, 60 % females) performed dual-task walking paradigms (even and uneven surface; with and without alphabeting cognitive task (ABC)) to mimic real-world demands. Gait quality measures [speed(m/s), rhythmicity(steps/minute), stride time variability (%), adaptability (m/s
2 ), similarity, smoothness, power (Hz) and regularity] were calculated from an accelerometer worn on the lower back. Linear-mixed modelling and Tukey analysis were used to analyze independent effects of surface and cognitive task and their interaction on gait quality. Partial Spearman correlations compared gait quality with global cognition and executive function., Results: No interaction effects between surface and cognitive task were found. Uneven surface reduced gait speed(m/s) (β = -0.07). Adjusted for speed, uneven surface reduced gait smoothness (β = -0.27) and increased regularity (β = 0.09), Tukey p < .05, for even vs uneven and even-ABC vs uneven-ABC. Cognitive task reduced gait speed(m/s) (β = -0.12). Adjusted for speed, cognitive task increased variability (β = 7.60), reduced rhythmicity (β = -6.68) and increased regularity (β = 0.05), Tukey p < .05, for even vs even-ABC and uneven vs uneven-ABC. With demographics as covariates, gait speed was not associated with cognition. Gait quality [lower variability during even-ABC (ρp =-.31) and uneven-ABC (ρp =-.28); greater rhythmicity (ρp between.22 and.29) and greater signal-adaptability AP (ρp between.22 and.26) during all walking tasks] was associated with better global cognition. Gait adaptability during even (ρp =-0.21, p = 0.03) and uneven(ρp =-0.19, p = 0.04) walking was associated with executive function., Significance: Surface and cognitive walking tasks independently affected gait quality. Our study with high-functioning older adults suggests that task-related changes in gait quality are related to subtle changes in cognitive functioning., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2023
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45. Temporal Sequence of Laryngeal Vestibule Closure and Reopening is Associated With Airway Protection.
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Shu K, Perera S, Mahoney AS, Mao S, Coyle JL, and Sejdić E
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- Humans, Deglutition, Cineradiography, Biomechanical Phenomena, Fluoroscopy methods, Larynx, Deglutition Disorders etiology
- Abstract
Background: Upper esophageal sphincter opening (UESO), and laryngeal vestibule closure (LVC) are two essential kinematic events whose timings are crucial for adequate bolus clearance and airway protection during swallowing. Their temporal characteristics can be quantified through time-consuming analysis of videofluoroscopic swallow studies (VFSS)., Objectives: We sought to establish a model to predict the odds of penetration or aspiration during swallowing based on 15 temporal factors of UES and laryngeal vestibule kinematics., Methods: Manual temporal measurements and ratings of penetration and aspiration were conducted on a videofluoroscopic dataset of 408 swallows from 99 patients. A generalized estimating equation model was deployed to analyze association between individual factors and the risk of penetration or aspiration., Results: The results indicated that the latencies of laryngeal vestibular events and the time lapse between UESO onset and LVC were highly related to penetration or aspiration. The predictive model incorporating patient demographics and bolus presentation showed that delayed LVC by 0.1 s or delayed LVO by 1% of the swallow duration (average 0.018 s) was associated with a 17.19% and 2.68% increase in odds of airway invasion, respectively., Conclusion: This predictive model provides insight into kinematic factors that underscore the interaction between the intricate timing of laryngeal kinematics and airway protection. Recent investigation in automatic noninvasive or videofluoroscopic detection of laryngeal kinematics would provide clinicians access to objective measurements not commonly quantified in VFSS. Consequently, the temporal and sequential understanding of these kinematics may interpret such measurements to an estimation of the risk of aspiration or penetration which would give rise to rapid computer-assisted dysphagia diagnosis., Level of Evidence: 2 Laryngoscope, 133:521-527, 2023., (© 2022 The American Laryngological, Rhinological and Otological Society, Inc.)
- Published
- 2023
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46. Cervical Vertebral Height Approximates Hyoid Displacement in Videofluoroscopic Images of Healthy Adults.
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Mahoney AS, Khalifa Y, Lucatorto E, Sejdić E, and Coyle JL
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- Adult, Humans, Deglutition, Cineradiography methods, Cervical Vertebrae diagnostic imaging, Hyoid Bone diagnostic imaging, Deglutition Disorders diagnostic imaging
- Abstract
Clinicians and researchers commonly judge the completeness of hyoid displacement from videofluoroscopic swallow study (VFSS) videos. Judgments made during the clinical exam are often subjective, and post-examination analysis reduces the measure's immediate value. This study aimed to determine the validity and feasibility of a visual, anatomically scaled benchmark for judging complete hyoid displacement during a VFSS. The third and fourth cervical vertebral bodies (C3 and C4) lie at roughly the same vertical position as the hyoid body and are strongly correlated with patient height. We hypothesized that anterior and superior displacement of the hyoid bone would approximate the height of one C3 or C4 body during safe swallows. Trained raters marked points of interest on C3, C4, and the hyoid body on 1414 swallows of adult patients with suspected dysphagia (n = 195) and 50 swallows of age-matched healthy participants (n = 17), and rated Penetration Aspiration Scale scores. Results indicated that the mean displacements of the hyoid bone were greater than one C3 unit in the superior direction for all swallows from patient and healthy participants, though significantly and clinically greater in healthy participant swallows (p < .001, d > .8). The mean anterior and superior displacements from patient and healthy participant swallows were greater than one C4 unit. Results show preliminary evidence that use of the C3 and/or C4 anatomic scalars can add interpretive value to the immediate judgment of hyoid displacement during the conduct of a clinical VFSS examination., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)
- Published
- 2022
- Full Text
- View/download PDF
47. Characterizing Effortful Swallows from Healthy Community Dwelling Adults Across the Lifespan Using High-Resolution Cervical Auscultation Signals and MBSImP Scores: A Preliminary Study.
- Author
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Donohue C, Khalifa Y, Perera S, Sejdić E, and Coyle JL
- Subjects
- Adult, Auscultation methods, Deglutition physiology, Humans, Independent Living, Longevity, Deglutition Disorders diagnosis
- Abstract
There is growing enthusiasm to develop inexpensive, non-invasive, and portable methods that accurately assess swallowing and provide biofeedback during dysphagia treatment. High-resolution cervical auscultation (HRCA), which uses acoustic and vibratory signals from non-invasive sensors attached to the anterior laryngeal framework during swallowing, is a novel method for quantifying swallowing physiology via advanced signal processing and machine learning techniques. HRCA has demonstrated potential as a dysphagia screening method and diagnostic adjunct to VFSSs by determining swallowing safety, annotating swallow kinematic events, and classifying swallows between healthy participants and patients with a high degree of accuracy. However, its feasibility as a non-invasive biofeedback system has not been explored. This study investigated 1. Whether HRCA can accurately differentiate between non-effortful and effortful swallows; 2. Whether differences exist in Modified Barium Swallow Impairment Profile (MBSImP) scores (#9, #11, #14) between non-effortful and effortful swallows. We hypothesized that HRCA would accurately classify non-effortful and effortful swallows and that differences in MBSImP scores would exist between the types of swallows. We analyzed 247 thin liquid 3 mL command swallows (71 effortful) to minimize variation from 36 healthy adults who underwent standardized VFSSs with concurrent HRCA. Results revealed differences (p < 0.05) in 9 HRCA signal features between non-effortful and effortful swallows. Using HRCA signal features as input, decision trees classified swallows with 76% accuracy, 76% sensitivity, and 77% specificity. There were no differences in MBSImP component scores between non-effortful and effortful swallows. While preliminary in nature, this study demonstrates the feasibility/promise of HRCA as a biofeedback method for dysphagia treatment., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)
- Published
- 2022
- Full Text
- View/download PDF
48. Facilitators and barriers to real-life mobility in community-dwelling older adults: a narrative review of accelerometry- and global positioning system-based studies.
- Author
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Suri A, VanSwearingen J, Dunlap P, Redfern MS, Rosso AL, and Sejdić E
- Subjects
- Accelerometry, Aged, Gait, Geographic Information Systems, Humans, Independent Living, Wearable Electronic Devices
- Abstract
Real-life mobility, also called "enacted" mobility, characterizes an individual's activity and participation in the community. Real-life mobility may be facilitated or hindered by a variety of factors, such as physical abilities, cognitive function, psychosocial aspects, and external environment characteristics. Advances in technology have allowed for objective quantification of real-life mobility using wearable sensors, specifically, accelerometry and global positioning systems (GPSs). In this review article, first, we summarize the common mobility measures extracted from accelerometry and GPS. Second, we summarize studies assessing the associations of facilitators and barriers influencing mobility of community-dwelling older adults with mobility measures from sensor technology. We found the most used accelerometry measures focus on the duration and intensity of activity in daily life. Gait quality measures, e.g., cadence, variability, and symmetry, are not usually included. GPS has been used to investigate mobility behavior, such as spatial and temporal measures of path traveled, location nodes traversed, and mode of transportation. Factors of note that facilitate/hinder community mobility were cognition and psychosocial influences. Fewer studies have included the influence of external environments, such as sidewalk quality, and socio-economic status in defining enacted mobility. Increasing our understanding of the facilitators and barriers to enacted mobility can inform wearable technology-enabled interventions targeted at delaying mobility-related disability and improving participation of older adults in the community., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)
- Published
- 2022
- Full Text
- View/download PDF
49. Remote and wearable ECG devices with diagnostic abilities in adults: A state-of-the-science scoping review.
- Author
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Bouzid Z, Al-Zaiti SS, Bond R, and Sejdić E
- Subjects
- Adult, Electrocardiography methods, Electrocardiography, Ambulatory methods, Humans, Reproducibility of Results, Atrial Fibrillation diagnosis, Wearable Electronic Devices
- Abstract
The electrocardiogram (ECG) records the electrical activity in the heart in real time, providing an important opportunity to detecting various cardiac pathologies. The 12-lead ECG currently serves as the "standard" ECG acquisition technique for diagnostic purposes for many cardiac pathologies other than arrhythmias. However, the technical aspects of acquiring a 12-lead ECG are not easy. and its usage currently is restricted to trained medical personnel, which limits the scope of its usefulness. Remote and wearable ECG devices have attempted to bridge this gap by enabling patients to take their own ECG using a simplified method at the expense of a reduced number of leads, usually a single-lead ECG. In this review, we summarize the studies that investigated the use of remote ECG devices and their clinical utility in diagnosing cardiac pathologies. Eligible studies discussed Food and Drug Administration-cleared, commercially available devices that were validated in an adult population. We summarize technical logistics of signal quality and device reliability, dimensional and functional features, and diagnostic value. Our synthesis shows that reduced-set ECG wearables have huge potential for long-term monitoring, particularly if paired with real-time notification techniques. Such capabilities make them primarily useful for abnormal rhythm detection, and there is sufficient evidence that a remote ECG device can be superior to the traditional 12-lead ECG in diagnosing specific arrhythmias such as atrial fibrillation. However, this review identifies important challenges faced by this technology and highlights the limited availability of clinical research examining their usefulness., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
50. Establishing Reference Values for Temporal Kinematic Swallow Events Across the Lifespan in Healthy Community Dwelling Adults Using High-Resolution Cervical Auscultation.
- Author
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Donohue C, Khalifa Y, Mao S, Perera S, Sejdić E, and Coyle JL
- Subjects
- Adult, Auscultation methods, Biomechanical Phenomena, Deglutition, Humans, Independent Living, Longevity, Reference Values, Deglutition Disorders diagnosis
- Abstract
Few research studies have investigated temporal kinematic swallow events in healthy adults to establish normative reference values. Determining cutoffs for normal and disordered swallowing is vital for differentially diagnosing presbyphagia, variants of normal swallowing, and dysphagia; and for ensuring that different swallowing research laboratories produce consistent results in common measurements from different samples within the same population. High-resolution cervical auscultation (HRCA), a sensor-based dysphagia screening method, has accurately annotated temporal kinematic swallow events in patients with dysphagia, but hasn't been used to annotate temporal kinematic swallow events in healthy adults to establish dysphagia screening cutoffs. This study aimed to determine: (1) Reference values for temporal kinematic swallow events, (2) Whether HRCA can annotate temporal kinematic swallow events in healthy adults. We hypothesized (1) Our reference values would align with a prior study; (2) HRCA would detect temporal kinematic swallow events as accurately as human judges. Trained judges completed temporal kinematic measurements on 659 swallows (N = 70 adults). Swallow reaction time and LVC duration weren't different (p > 0.05) from a previously published historical cohort (114 swallows, N = 38 adults), while other temporal kinematic measurements were different (p < 0.05), suggesting a need for further standardization to feasibly pool data analyses across laboratories. HRCA signal features were used as input to machine learning algorithms and annotated UES opening (69.96% accuracy), UES closure (64.52% accuracy), LVC (52.56% accuracy), and LV re-opening (69.97% accuracy); providing preliminary evidence that HRCA can noninvasively and accurately annotate temporal kinematic measurements in healthy adults to determine dysphagia screening cutoffs., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)
- Published
- 2022
- Full Text
- View/download PDF
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