| 1. |
- Zhong, Jicun, et al.
(författare)
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Imaging, image processing and pattern analysis of skin capillary ensembles
- 2000
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 6:2, s. 45-57
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Tidskriftsartikel (refereegranskat)abstract
- Background/aims: The capillary bed is recognized as the site where metabolic and nutrient processes occur for living tissues at all levels. The evaluation of this vital process is a major concern in microcirculation. Unlike traditional approaches that concentrated on the extreme local properties of this process, a more global analysis toward capillary ensembles is employed here, since capillaries work as a cooperative entirety. As a first step toward ensemble analysis, the static and planar geometric parameters are investigated. Parameters such as the capillary adjacency and size information are very important in predicting and analysing certain malfunctions in the microvascular bed.Methods/results: In order to achieve an objective and accurate analysis of these vital parameters, a computerized imaging system is proposed. Not only the number of capillaries and the capillary cross-sectional areas are important in describing the microvascular bed but the planar distribution pattern of the capillaries also carries valid information. This information, unique to the ensemble analysis, can be used to reveal, visualise and quantify the clustering of capillaries; and this information, according to the Krogh model, is fundamental in estimating the tissue oxygen supply. Two spatial models, the closest neighbor and triangulation methods, have been applied to the captured images of capillary ensembles. The closest neighbor technique generates a minimal distance map or displays a distribution, which depicts the local clustering of capillaries. The triangulation technique, on the other hand, generates a mutual distance map, which is a global description of the capillary positions. Triangulation methods have been evaluated but all except the Greedy triangulation method have been rejected due to lack of robustness and model weakness. Therefore, the capillaries are triangulated by the Greedy triangulation method, and the capillary distribution uniformity is defined as one minus the coefficient of variance of the edge lengths of the mutual distance map.Conclusions: A series of advanced image processing methods have been developed that efficiently extract the capillary position, size and distribution information from the images. These results facilitate the automatic counting of capillaries and the capillary size-related pathological analysis.
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| 2. |
- Bergstrand, Sara, et al.
(författare)
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Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques
- 2009
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Ingår i: Skin research and technology. - : Wiley-Blackwell. - 0909-752X .- 1600-0846. ; 15:2, s. 139-147
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Tidskriftsartikel (refereegranskat)abstract
- Background/purpose: This study has evaluated a multi-parametric system combining laser Doppler flowmetry and photoplethysmography in a single probe for the simultaneous measurement of blood flow at different depths in the tissue. This system will be used to facilitate the understanding of pressure ulcer formation and in the evaluation of pressure ulcer mattresses.Methods: The blood flow in the tissue over the sacrum was measured before, during and after loading with 37.5 mmHg, respectively, 50.0 mmHg. The evaluation of the system consisted of one clinical part, and the other part focusing on the technicalities of the probe prototype.Results: An increase in blood flow while loading was the most common response, but when the blood flow decreased during loading it was most affected at the skin surface and the blood flow responses may be different due to depths of measurement. Reactive hyperaemia may occur more frequently in the superficial layers of the tissue.Conclusion: The study showed that the new system is satisfactory for measuring tissue blood flow at different depths. The laser Doppler complements the photoplethysmography, and further development of the system into a thin flexible probe with the ability to measure a larger area is required.
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| 3. |
- 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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| 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. |
- Bodén, Ida, 1977-, et al.
(författare)
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In vivo skin measurements with a novel probe head for simultaneous skin impedance and near-infrared spectroscopy
- 2011
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 17:4, s. 494-504
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Tidskriftsartikel (refereegranskat)abstract
- Background/purpose: Near-infrared (NIR) spectroscopy and skin impedance (IMP) measurements are useful techniques for objective diagnostics of various skin diseases. Here, we present a combined probe head for simultaneous, time-saving NIR spectroscopy and skin impedance measurements. The probe also ensures that both measurements are performed under equal conditions and at the same skin location.Methods: Finite element method simulations were performed for evaluation of the impedance. In vivo skin measurements were performed and combined NIR and impedance spectra were analysed by means of multivariate methods with respect to body location, age and gender. The classification rate was determined by a planar discriminant analysis. Reproducibility was investigated by calculation of scatter values and statistical significance between overlapping groups was assessed by the calculation of intra-model distances, q.Results: The novel probe yielded rapid reproducible results and was easy to manage. Significant differences between skin locations and to a lesser extent age groups and gender were demonstrated.Conclusion: With the novel probe, statistically significant differences between overlapping classes in score plots can be confirmed by calculating intra-model distances. The influence of molecular differences in the skin at different body locations is larger than the influence of gender or age and therefore relevant reference measurements are discussed.
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| 6. |
- Bodén, Ida, 1977-, et al.
(författare)
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NIR and skin impedance spectroscopic measurements for studying the effect of coffee and alcohol on skin, and dysplastic naevi
- 2012
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Ingår i: Skin research and technology. - : Wiley-Blackwell. - 0909-752X .- 1600-0846. ; 18:4, s. 486-494
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Tidskriftsartikel (refereegranskat)abstract
- Background/purpose: Near infrared (NIR) and impedance spectroscopy can be used for clinical skin measurements and need to be evaluated for possible confounding factors; (a) are skin conditions of the patient and the subsequent skin measurements influenced by alcohol and/or coffee consumption and (b) are measurements of dysplastic naevi (DN) reproducible over time and significantly different compared to reference skin.Methods: NIR and skin impedance spectroscopic data were analysed multivariately. In the first study, the skin characteristics of 15 healthy individuals were examined related to body location, gender, individual differences, and consumption of coffee or alcohol. The second study included five patients diagnosed with dysplastic naevi syndrome (DNS). Measurements were taken on DN and reference skin over time.Results: In the first study, body location and gender had a major influence on measurement scores. Inter-individual skin characteristics and coffee or alcohol effects on skin characteristics were of minor importance. In the second study, it was shown that DN can be differentiated from reference skin and the measurements are stable over time.Conclusions: Moderate consumption of alcohol and coffee did not influence the results of the measurements. It is possible to follow, stable or changed, characteristics of DN over time.
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| 7. |
- Bodén, Ida, 1977-, et al.
(författare)
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Non-invasive identification of melanoma with near-infrared and skin impedance spectroscopy
- 2013
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Ingår i: Skin research and technology. - : John Wiley & Sons. - 0909-752X .- 1600-0846. ; 19:1, s. e473-e478
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Tidskriftsartikel (refereegranskat)abstract
- Background/purpose: An early diagnosis of cutaneous malignant melanoma is of high importance for good prognosis. An objective, non-invasive instrument could improve the diagnostic accuracy of melanoma and decrease unnecessary biopsies. The aim of this study was to investigate the use of Near infrared and skin impedance spectroscopy in combination as a tool to distinguish between malignant and benign skin tumours.Methods: Near infrared and skin impedance spectra were collected in vivo on 50 naevi or suspect melanomas prior to excision. Received data was analysed with multivariate techniques and the results were compared to histopathology analyses of the tumours. A total of 12 cutaneous malignant melanomas, 19 dysplastic naevi and 19 benign naevi were included in the study.Results: The observed sensitivity and specificity of the proposed method were 83% and 95%, respectively, for malignant melanoma.Conclusions: The results indicate that the combination of near infrared and skin impedance spectroscopy is a promising tool for non-invasive diagnosis of suspect cutaneous malignant melanomas.
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| 8. |
- Clancy, Neil T, et al.
(författare)
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A new device for assessing changes in skin viscoelasticity using indentation and optical measurement
- 2010
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Ingår i: SKIN RESEARCH AND TECHNOLOGY. - : Blackwell Publishing Ltd. - 0909-752X .- 1600-0846. ; 16:2, s. 210-228
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Tidskriftsartikel (refereegranskat)abstract
- Background/aims Skin is a viscoelastic material, comprised of fluidic and fibrous components. Changes in viscoelasticity can arise due to a number of conditions including dehydration, swelling (associated with injury or disease), impaired heart function, rehydration therapy, ageing, scarring, sun exposure and genetic conditions affecting connective tissue. Quantification of changes in skin viscoelasticity due to these processes is of great clinical interest in the fields of therapy monitoring, wound healing and disease screening. However, devices currently available to measure aspects of the mechanical properties of skin have limitations in ease-of-use, accessibility, and depth of measurement. This paper describes a new technique to follow changes in the viscoelasticity of the skin, using a novel approach to an indentation manoeuvre. The device is portable, low-cost and easy to use while at the same time providing rich information on the mechanical response of the skin. Methods The method proposed optically tracks the skins recovery from an initial strain, made with a novel linear indentor, using diffuse side-lighting and a CCD video camera. Upon indentation, the skins elastin fibres are stretched and fluid is displaced from the compressed region. When the indentor is removed, the rate of recovery of the skin from this imprint is therefore principally dependent on its hydration and elasticity. Using the blue colour plane of the image and polarisation filtering, it is possible to examine the surface topography only, and track the decay of the imprint over time. Results The decrease in size of the imprint over time (decay curve) recorded by the device is shown to agree with the theoretical predictions of an appropriate viscoelastic model of skin mechanical behaviour. The contributors to the response measured using the indentation device are fully characterised and evaluated using separate measurement techniques including high-frequency ultrasound, polarisation spectroscopy and optical coherence tomography. Conclusion The device developed is capable of tracking the viscoelastic response of skin to minimal indentation. The high precision achieved using low-cost materials means that the device could be a viable alternative to current technologies.
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| 9. |
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| 10. |
- Falk, Magnus, et al.
(författare)
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Inter-observer variability in reading of phototest reactions with sharply or diffusely delineated borders
- 2008
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 14:4, s. 397-402
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Tidskriftsartikel (refereegranskat)abstract
- Background: In both clinical and experimental phototesting, naked eye assessment of erythema has been the main assessment parameter. As with all subjective assessment, variability in recorded results due to variable circumstances around the performance and reading of tests influences reliability and utility of data whether they be interpreted for an individual patient or for a group of research subjects. Methods: In the present study, variability in the reporting of diameter of ultraviolet B (UVB) erythema has been studied. The erythematous reactions were assessed by the naked eye and with the help of a millimetre-graded ruler by a group of dermatologists and dermatological trainees. Reaction size, objectively quantified by means of laser Doppler perfusion imaging (LDPI) using thresholding of the reaction perfusion, and known size of UVB provocation were used as yardsticks in order to quantify this variability. Results: Agreement between observers, against known size, was excellent for reactions with a sharp border, but for reactions with a diffuse or indistinct border there was a substantial inter-observer variability. This was also true for the comparison between naked-eye reading and LDPI assessment of the reaction size. Conclusion: It is concluded that if naked-eye readings are to be the outcome measurement, then provocations/protocols producing distinct borders are an advantage. If borders between provoked and unprovoked skin can be expected to be diffuse, i.e. part of a continuum of response, the use of objective, bioengineering techniques such as LDPI is required. Quantitative methods are also the basis for more detailed presentation and interpretation of test results including information on dose response above the minimal erythema dose.
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