| 1. |
- Abbasiasl, Taher, et al.
(författare)
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A Flexible Cystoscope Based on Hydrodynamic Cavitation for Tumor Tissue Ablation
- 2022
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9294 .- 1558-2531. ; 69:1, s. 513-524
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Hydrodynamic cavitation is characterized by the formation of bubbles inside a flow due to local reduction of pressure below the saturation vapor pressure. The resulting growth and violent collapse of bubbles lead to a huge amount of released energy. This energy can be implemented in different fields such as heat transfer enhancement, wastewater treatment and chemical reactions. In this study, a cystoscope based on small scale hydrodynamic cavitation was designed and fabricated to exploit the destructive energy of cavitation bubbles for treatment of tumor tissues. The developed device is equipped with a control system, which regulates the movement of the cystoscope in different directions. According to our experiments, the fabricated cystoscope was able to locate the target and expose cavitating flow to the target continuously and accurately. The designed cavitation probe embedded into the cystoscope caused a significant damage to prostate cancer and bladder cancer tissues within less than 15 minutes. The results of our experiments showed that the cavitation probe could be easily coupled with endoscopic devices because of its small diameter. We successfully integrated a biomedical camera, a suction tube, tendon cables, and the cavitation probe into a 6.7 mm diameter cystoscope, which could be controlled smoothly and accurately via a control system. The developed device is considered as a mechanical ablation therapy, can be a solid alternative for minimally invasive tissue ablation methods such as radiofrequency (RF) and laser ablation, and could have lower side effects compared to ultrasound therapy and cryoablation.
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| 2. |
- Aberg, P., et al.
(författare)
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Skin cancer identification using multifrequency electrical impedance - A potential screening tool
- 2004
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Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531. ; 51:12, s. 2097-2102
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Tidskriftsartikel (refereegranskat)abstract
- Electrical bio-impedance can be used to assess skin cancers and other cutaneous lesions. The aim of this study was to distinguish skin cancer from benign nevi using multifrequency impedance spectra. Electrical impedance spectra of about 100 skin cancers and 511 benign nevi were measured. Impedance of reference skin was measured ipsi-laterally to the lesions. The impedance relation between lesion and reference skin was used to distinguish the cancers from the nevi. It was found that it is possible to separate malignant melanoma from benign nevi with 75% specificity at 100% sensitivity, and to distinguish nonmelanoma skin cancer from benign nevi with 87% specificity at 100% sensitivity. The power of skin cancer detection using electrical impedance is as good as, or better than, conventional visual screening made by general practitioners.
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| 3. |
- Ahlström, Christer, et al.
(författare)
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Assessing Aortic Stenosis using Sample Entropy of the Phonocardiographic Signal in Dogs
- 2008
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Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531. ; 55:8, s. 2107-2109
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Tidskriftsartikel (refereegranskat)abstract
- In aortic valve stenosis (AS), heart murmurs arise as an effect of turbulent blood flow distal to the obstructed valves. With increasing AS severity, the flow becomes more unstable, and the ensuing murmur becomes more complex. We hypothesize that these hemodynamic flow changes can be quantified based on the complexity of the phonocardiographic (PCG) signal. In this study, sample entropy (SampEn) was investigated as a measure of complexity using a dog model. Twenty-seven boxer dogs with various degrees of AS were examined with Doppler echocardiography, and the peak aortic flow velocity (Vmax) was used as a reference of AS severity. SampEn correlated to Vmax with R = 0.70 using logarithmic regression. In a separate analysis, significant differences were found between physiologic murmurs and murmurs caused by AS (p < 0.05), and the area under a receiver operating characteristic curve was calculated to 0.96. Comparison with previously presented PCG measures for AS assessment showed improved performance when using SampEn, especially for differentiation between physiological murmurs and murmurs caused by mild AS. Studies in patients will be needed to properly assess the technique in humans.
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| 4. |
- Ala, Tirdad Seifi, et al.
(författare)
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Alpha Oscillations During Effortful Continuous Speech: From Scalp EEG to Ear-EEG
- 2023
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Ingår i: IEEE Transactions on Biomedical Engineering. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9294 .- 1558-2531. ; 70:4, s. 1264-1273
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The purpose of this study was to investigate alpha power as an objective measure of effortful listening in continuous speech with scalp and ear-EEG. Methods: Scalp and ear-EEG were recorded simultaneously during presentation of a 33-s news clip in the presence of 16-talker babble noise. Four different signal-to-noise ratios (SNRs) were used to manipulate task demand. The effects of changes in SNR were investigated on alpha event-related synchronization (ERS) and desynchronization (ERD). Alpha activity was extracted from scalp EEG using different referencing methods (common average and symmetrical bi-polar) in different regions of the brain (parietal and temporal) and ear-EEG. Results: Alpha ERS decreased with decreasing SNR (i.e., increasing task demand) in both scalp and ear-EEG. Alpha ERS was also positively correlated to behavioural performance which was based on the questions regarding the contents of the speech. Conclusion: Alpha ERS/ERD is better suited to track performance of a continuous speech than listening effort. Significance: EEG alpha power in continuous speech may indicate of how well the speech was perceived and it can be measured with both scalp and Ear-EEG.
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| 5. |
- Asplund, Maria, et al.
(författare)
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Construction of wire electrodesand 3D woven logicas a potential technology forneuroprosthetic implants
- 2008
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Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- New strategies to improve neuron coupling to neuroelectronic implants are needed. In particular, tomaintain functional coupling between implant and neurons, foreign body response like encapsulation must meminimized. Apart from modifying materials to mitigate encapsulation it has been shown that with extremely thinstructures, encapsulation will be less pronounced. We here utilize wire electrochemical transistors (WECTs) usingconducting polymer coated fibers. Monofilaments down to 10 μm can be successfully coated and weaved intocomplex networks with built in logic functions, so called textile logic. Such systems can control signal patterns at alarge number of electrode terminals from a few addressing fibres. Not only is fibre size in the range where lessencapsulation is expected but textiles are known to make successful implants because of their soft and flexiblemechanical properties. Further, textile fabrication provides versatility and even three dimensional networks arepossible. Three possible architectures for neuroelectronic systems are discussed. WECTs are sensitive to dehydrationand materials for better durability or improved encapsulation is needed for stable performance in biologicalenvironments.
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| 6. |
- Barbé, Kurt, et al.
(författare)
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Fractional-Order Time Series Models for Extracting the Haemodynamic Response From Functional Magnetic Resonance Imaging Data
- 2012
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Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531. ; 59:8, s. 2264-2272
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Tidskriftsartikel (refereegranskat)abstract
- The postprocessing of functional magnetic resonance imaging (fMRI) data to study the brain functions deals mainly with two objectives: signal detection and extraction of the haemodynamic response. Signal detection consists of exploring and detecting those areas of the brain that are triggered due to an external stimulus. Extraction of the haemodynamic response deals with describing and measuring the physiological process of activated regions in the brain due to stimulus. The haemodynamic response represents the change in oxygen levels since the brain functions require more glucose and oxygen upon stimulus that implies a change in blood flow. In the literature, different approaches to estimate and model the haemodynamic response have been proposed. These approaches can be discriminated in model structures that either provide a proper representation of the obtained measurements but provide no or a limited amount of physiological information, or provide physiological insight but lacks a proper fit to the data. In this paper, a novel model structure is studied for describing the haemodynamics in fMRI measurements: fractional models. We show that these models are flexible enough to describe the gathered data with the additional merit of providing physiological information.
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| 7. |
- Bayford, Richard H., et al.
(författare)
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Locating Functionalized Gold Nanoparticles Using Electrical Impedance Tomography
- 2022
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Ingår i: IEEE Transactions on Biomedical Engineering. - : IEEE. - 0018-9294 .- 1558-2531. ; 69:1, s. 494-502
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Tidskriftsartikel (refereegranskat)abstract
- Objective: An imaging device to locate functionalised nanoparticles, whereby therapeutic agents are transported from the site of administration specifically to diseased tissues, remains a challenge for pharmaceutical research. Here, we show a new method based on electrical impedance tomography (EIT) to provide images of the location of gold nanoparticles (GNPs) and the excitation of GNPs with radio frequencies (RF) to change impedance permitting an estimation of their location in cell models Methods: We have created an imaging system using quantum cluster GNPs as contrast agent, activated with RF fields to heat the functionalized GNPs, which causes a change in impedance in the surrounding region. This change is then identified with EIT. Results: Images of impedance changes of around 80 ± 4% are obtained for a sample of citrate stabilized GNPs in a solution of phosphate-buffered saline. A second quantification was carried out using colorectal cancer cells incubated with culture media, and the internalization of GNPs into the colorectal cancer cells was undertaken to compare them with the EIT images. When the cells were incubated with functionalised GNPs, the change was more apparent, approximately 40 ± 2%. This change was reflected in the EIT image as the cell area was more clearly identifiable from the rest of the area. Significance: EIT can be used as a new method to locate functionalized GNPs in human cells and help in the development of GNP-based drugs in humans to improve their efficacy in the future.
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| 8. |
- Bayford, Richard H., et al.
(författare)
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Locating Functionalized Gold Nanoparticles Using Electrical Impedance Tomography
- 2022
-
Ingår i: IEEE Transactions on Biomedical Engineering. - : IEEE. - 0018-9294 .- 1558-2531. ; 69:1, s. 494-502
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: An imaging device to locate functionalised nanoparticles, whereby therapeutic agents are transported from the site of administration specifically to diseased tissues, remains a challenge for pharmaceutical research. Here, we show a new method based on electrical impedance tomography (EIT) to provide images of the location of gold nanoparticles (GNPs) and the excitation of GNPs with radio frequencies (RF) to change impedance permitting an estimation of their location in cell models Methods: We have created an imaging system using quantum cluster GNPs as contrast agent, activated with RF fields to heat the functionalized GNPs, which causes a change in impedance in the surrounding region. This change is then identified with EIT. Results: Images of impedance changes of around 80 +/- 4% are obtained for a sample of citrate stabilized GNPs in a solution of phosphate-buffered saline. A second quantification was carried out using colorectal cancer cells incubated with culture media, and the internalization of GNPs into the colorectal cancer cells was undertaken to compare them with the EIT images. When the cells were incubated with functionalised GNPs, the change was more apparent, approximately 40 +/- 2%. This change was reflected in the EIT image as the cell area was more clearly identifiable from the rest of the area. Significance: EIT can be used as a new method to locate functionalized GNPs in human cells and help in the development of GNP-based drugs in humans to improve their efficacy in the future.
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| 9. |
- Bro, Viktor, 1991-, et al.
(författare)
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Continuous and discrete Volterra-Laguerre models with delay for modeling of smooth pursuit eye movements
- 2023
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Ingår i: IEEE Transactions on Biomedical Engineering. - : IEEE. - 0018-9294 .- 1558-2531. ; 70:1, s. 97-104
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Tidskriftsartikel (refereegranskat)abstract
- The mathematical modeling of the human smooth pursuit system from eye-tracking data is considered. Recently developed algorithms for the estimation of Volterra-Laguerre (VL) models with explicit time delay are applied in continuous and discrete time formulations to experimental data collected from Parkinsonian patients in different medication states and healthy controls. The discrete VL model with an explicit time delay and the method for its estimation are first introduced in this paper. The estimated parameters of a second-order VL model are shown to capture the ocular dynamics both in health and disease. The possibility of including the estimated time delay, along with the VL kernel parameters, into the set of the model parameters is explored. The results obtained in continuous VL modeling are compared with those in discrete time to discern the effects due to the sampling enforced by the eye tracker used for data acquisition.
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| 10. |
- Carlson, Jonas, et al.
(författare)
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Classification of Electrocardiographic P-wave Morphology
- 2001
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2531 .- 0018-9294. ; 48:4, s. 401-405
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Tidskriftsartikel (refereegranskat)abstract
- The atrial activity of the human heart is normally visible in the electrocardiogram as a P-wave. In patients with intermittent atrial fibrillation, a different P-wave morphology can sometimes be seen, indicating atrial conduction defects. The purpose of this study was to develop a method to discriminate between such P-waves and normal ones. 20 recordings of each type were used in a classification which, based on impulse response analysis of the P-wave and linear discrimination between various parameters, produced a correct classification in 37 of the 40 recordings (sensitivity 95%, specificity 90%)
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