| 1. |
- Aberg, P., et al.
(författare)
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Assessment of skin lesions and skin cancer using simple electrical impedance indices
- 2003
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 9:3, s. 257-261
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Tidskriftsartikel (refereegranskat)abstract
- Background/aims: Purpose of this investigation was to assess benign pigmented cellular nevus (BEN), basal cell carcinoma (BCC), dermatofibroma (DER), dysplastic nevus (DYS), and seborrheic keratoses (SEB) using in vivo noninvasive electrical impedance technique. Methods: Electrical impedance was measured at 258 BEN, 34 BCC, 17 DER, 35 DYS, and 26 SEB lesions. Controls were measured at healthy skin close to the lesions. The impedance was measured between 1 kHz and 1 MHz at five depth settings. After the impedance measurements the lesions were histopathologically diagnosed. The impedance spectra were parameterized to four indices prior to the statistical analysis of the data. Results: There were significant differences between the lesions and their controls for BEN (P<0.001), BCC (P<0.001), DYS (P<0.01), and SEB(P<0.01). Conclusions: There are clear statistical differences between impedance of common lesions and control skin. With some further developments, the impedance technique can be useful as a diagnostic decision support tool for skin cancer assessment.
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| 2. |
- Aberg, P., et al.
(författare)
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Non-invasive and microinvasive electrical impedance spectra of skin cancer - a comparison between two techniques
- 2005
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Ingår i: Skin research and technology. - 0909-752X .- 1600-0846. ; 11:4, s. 281-286
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Tidskriftsartikel (refereegranskat)abstract
- Background/purpose: Bio-electrical impedance spectra of skin cancer and other lesions can be assessed using both regular non-invasive probes and a novel type of microinvasive electrode system with a surface furnished with tiny spikes that penetrate stratum corneum. The aim of the study was to compare the accuracy of detection for various types of skin cancer using impedance spectra measured with these two different electrode systems in an objective way without optimising the power of discrimination. Methods: Impedance spectra of 99 benign nevi, 28 basal cell carcinomas (BCC), and 13 malignant melanomas (MM) were measured using the two electrode systems. Classification of the lesions was made using Fisher's linear discriminant, and the sensitivities and specificities of the techniques were estimated using cross-validation. Results: The best separation between nevi and BCC was achieved using the regular non-invasive probe (96% sensitivity and 86% specificity), whereas the best separation between nevi and MM was achieved using the microinvasive electrodes (92% sensitivity and 80% specificity). Conclusions: Our results indicate that the choice of electrode system is application dependent.
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| 3. |
- 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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| 4. |
- Aberg, P., et al.
(författare)
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Variation of skin properties within human forearms demonstrated by non-invasive detection and multi-way analysis
- 2002
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 8:3, s. 194-201
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Tidskriftsartikel (refereegranskat)abstract
- Background: It is known that the properties of human skin vary locally. The purpose of this study was to investigate the properties of human volar forearms even further using advanced non-invasive techniques and numerical methods. Methods: The skin properties of human volar forearms were investigated using measurements of trans epidermal water loss and multifrequency electrical impedance. Eight sites on the forearms of 27 healthy volunteers were measured. The sites were oriented as squares, four sites on both left and right forearm, approximately 40-50 mm apart. Results: Analysis of variance showed significant differences for epidermal water loss (P < 0.01) and the skin impedance (P < 0.001) between the inner and outer sides of the arms. Additionally, parallel factor analysis of the full skin impedance spectra also showed that there are systematic differences between right and left arm (P < 0.01). Conclusions: It is crucial to design skin studies carefully in order to minimise the effects of the local skin properties of human skin.
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| 5. |
- Griss, P., et al.
(författare)
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Micromachined electrodes for biopotential measurements
- 2001
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Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 10, s. 10-16
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Tidskriftsartikel (refereegranskat)abstract
- We describe the microfabrication, packaging and testing of a micromachined dry biopotential electrode, (i.e., where electrolytic gel is not required). It consists of an array of micro-dimensioned, very sharp spikes, (i.e., needles) designed for penetration of human skin which circumvent high impedance problems associated with layers of tbe outer skin. The spikes are etched in silicon by deep reactive ion etching and are subsequently covered with a silver-silverchloride (Ag-AgCl) double layer. The electrode-skin-electrode impedance of dry spiked electrodes having a size of 4 x 4 mm(2) is reduced compared to standard electrodes using electrolytic gel and having a comparable size, Recorded low amplitude biopotentials resulting from the activity of the brain, (i.e, EEG signals) are of high quality, even for spiked electrodes as small as 2 x 2 mm(2). The spiked electrode offers a promising alternative to standard electrodes in biomedical applications and is of interest in research of nem biomedical methods.
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| 6. |
- Jarverud, K., et al.
(författare)
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Analysis of the O-wave in acute right ventricular apex impedance measurements with a standard pacing lead in animals
- 2002
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Ingår i: Medical and Biological Engineering and Computing. - 0140-0118 .- 1741-0444. ; 40:5, s. 512-519
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Tidskriftsartikel (refereegranskat)abstract
- Modern pacemakers (implantable devices used for maintaining an appropriate heart rate in patients) can use an intracardiac ventricular impedance signal for physiological cardiac stimulation control. Intracardiac ventricular impedance from nine animal subjects is analysed and presented (seven sheep: 49.0 +/- 6.5 kg, sinus rhythm 100.3 +/- 16.5 beats min(-1), average impedance 629.8 +/- 72.6Omega; and two dogs: 30 kg each, sinus rhythm 86.0 beats min(-1), 862.1Omega and 134.0 beats min(-1), 1114.6Omega, respectively). The averaged curve and standard deviation curve of the impedance in sinus rhythm were analysed in MATLAB to clarify and study consistent impedance shape over one heart cycle. In eight of nine (89%) animal subjects, a consistent impedance slope change (notch) was observed in the early stage of the cardiac filling phase. This result was reproduced in an additional subject with simultaneous echocardiographical measurements of mitral valve blood flow. The notch occured soon after rapid early filling (E-wave in mitral flow) but prior to ventricular filling caused by atrial contraction, indicating that the impedance notch was caused by rapid ventricular filling and that it might be a sensed feature of diagnostic value. The intracardiac impedance notch in the present study had similar features to the non-invasive transthoracic impedance O-wave reported by others, and it is shown here that an O-wave is found in intracardiac impedance signals, strongly suggesting that the non-invasive O-wave is caused by cardiac events.
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| 7. |
- Nicander, I., et al.
(författare)
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Clinically normal atopic skin vs. non-atopic skin as seen through electrical impedance
- 2004
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 10:3, s. 178-183
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Tidskriftsartikel (refereegranskat)abstract
- Background/aims: In an earlier study, we have shown that the electrical impedance (IMP) is dependent on the lipid content of the stratum corneum as studied by lipid extraction. Therefore, we now employ the IMP technique to compare the properties of clinically normal atopic skin with that of non-atopic skin. We looked at the same time at concomitant alterations in transepidermal water loss (TEWL) and skin moisture results. Methods: Twenty-two healthy participants and 26 patients with atopic dermatitis were recruited. One test site on each volar forearm was used in the test procedure, of cyclohexane swabbing, skin stripping, and lipid extraction using a mixture of hexane:isopropanol. Responses were evaluated by measuring TEWL, skin moisture using electrical capacitance, and finally IMP spectroscopy in the frequency range 1 kHz to 1 MHz before the start of the study, after each step of the test procedure, and also during a 2 weeks recovery period. Results: Only the IMP results showed significant changes between baseline values of clinically normal atopic skin and healthy skin. Furthermore, IMP and TEWL showed significantly larger reactivity for the atopic group after the skin stripping procedure, and IMP after lipid extraction as well. Conclusion: Our results show that IMP is a useful method for detection of changes in the lipid content of the stratum corneum by discriminating healthy looking atopic skin from healthy control skin, and to detect changes in reactivity between the two groups.
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| 8. |
- Nicander, I., et al.
(författare)
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Electrical impedance measurements at different skin sites related to seasonal variations
- 2000
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 6:2, s. 81-86
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Tidskriftsartikel (refereegranskat)abstract
- Background/aims: In a previous study we mapped differences in electrical impedance between different anatomical locations related to age and sex. Now we employ the electrical impedance technique for studying the seasonal variations for the same skin sites. Method: The investigation was performed on 48 healthy volunteers divided into two groups on the basis of sex. Readings of electrical impedance were taken from ten different body locations at each of the four seasons during one year. Electrical impedance spectra were measured in the frequency range 1 kHz to 1 MHz, acid four impedance indices based on the complex impedance values at 20 kHz and 500 kHz were calculated. Results: The baseline values varied from one site to another and increased significantly for most sites from the winter to the summer, while the changes from October to March were negligible. Using ANOVA, the seasonal variation was found to be a more important factor than sex. Conclusions: Our results suggest that seasonal variations for different skin sites should be taken into consideration when using the electrical impedance technique.
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| 9. |
- Nicander, I., et al.
(författare)
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The ability of betaine to reduce the irritating effects of detergents assessed visually, histologically and by bioengineering methods
- 2003
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 9:1, s. 50-58
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Tidskriftsartikel (refereegranskat)abstract
- Background/aims: A novel approach for reducing the undesired irritating properties of detergents on skin might be offered by betaine, which is a natural product derived from the sugar beet. The aim of the study was to explore the ability of betaine to reduce the irritating effects of two surfactants, sodium lauryl sulphate (SLS) and cocoamidopropylbetaine (CAPB). For evaluation of changes in skin reactions visual scoring, electrical impedance, transepidermal water loss and histology were used. Methods: Twenty-one healthy subjects were patch tested for 24 h with SLS and CAPB alone and together with betaine, betaine alone, and the two controls distilled water and an unoccluded test site on both volar forearms. Responses were evaluated by measuring electrical impedance and transepidermal water loss before exposure and 24 h after the removal of the test substances, and also by visual inspection and histology. The electrical impedance device enables measurements at 31 frequencies and relevant information was extracted from the spectra using four indices. Results: CAPB was found to be less irritating than SLS. The used detergents gave rise to distinctive impedance patterns also reflected by different types of histopathological skin responses. After the adding of betaine, the irritant reaction decreased for both detergents. Conclusions: Betaine is a promising ingredient to reduce the side effects of detergents and electrical impedance is a suitable tool both to quantify the degree of irritation as well as to differentiate between various types of reactions.
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| 10. |
- Nicander, I., et al.
(författare)
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The use of different concentrations of betaine as a reducing irritation agent in soaps monitored visually and non-invasively
- 2003
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 9:1, s. 43-49
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Tidskriftsartikel (refereegranskat)abstract
- Background/aims: Products containing detergents can damage the skin and give rise to irritant contact dermatitis. Therefore, attempts have been made to find less irritating detergents as well as substances decreasing undesired side-effects of detergents, and a novel approach is offered by betaine. The aim of the study has been to determine the irritating properties of some liquid soaps for personal hygiene and to map the effect of different concentrations of betaine using electrical impedance, trans -epidermal water loss and visual inspection. Methods: Twenty-eight healthy subjects were patch tested with different commercial soaps with and without betaine and sodium lauryl sulphate on both volar forearms for 24 h. A site with distilled water and an unoccluded area were used as references. Responses of the skin reactions were evaluated by visual inspection and by measuring trans-epidermal water loss and electrical impedance before application and 24 h after removal of the chambers. Results/conclusions: Significant skin reactions were found for all soaps tested but the soaps containing betaine were the least irritating. However, the skin irritation did not decrease with increasing concentrations of betaine in the tested range. On the whole the differences between the products were not large. The non-invasive methods used were more sensitive than visual assessment for evaluation of invisible or barely visible skin responses.
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