Stig Ollmar

Skin cancer identification using multifrequency electrical impedance-a potential screening tool

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.

Non-invasive and microinvasive electrical impedance spectra of skin cancer - a comparison between two techniques

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.

Correlation of impedance response patterns to histological findings in irritant skin reactions induced by various surfactants

Summary We have explored the use of measurements of electrical impedance to discriminate between the effects of different irritant substances upon the skin, and have studied the relationships between impedance and histopathological change. Three compounds with different chemical profiles were tested on volunteers: sodium lauryl sulphate, benzalkonium chloride and nonanoic acid. The concentrations selected were such that each irritant produced responses of a similar order, as judged by visual scores. The magnitude and phase of electrical impedance were measured and, for comparison, also the transepidermal water loss. Four physically distinct aspects (indices) were devised from the impedance data, and the values obtained were statistically analysed. The three irritants produced different effects, giving distinctive impedance patterns. These were also found to be reflected by three different types of histopathological skin response. Our results suggest that the indices can be used to classify irritant contact reactions, which it is difficult or impossible to achieve by other non‐invasive techniques.

Electrical impedance measured to five skin depths in mild irritant dermatitis induced by sodium lauryl sulphate

The non‐invasive electrical impedance technique used in this study reflects structural changes in a tissue, and provides an estimate of the level of oedema by a simple impedance index.

Electrical impedance applied to non-invasive detection of irritation in skin.

Healthy volunteers were subjected to irritation by sodium lauryl sulphate at concentrations in the range 0.002% to 5.0% applied in Finn Chambers for 24 h. Test sites were visually assessed 1 h and 24 h niter cessation of exposure. At the same limes electrical impedance was measured with a new impedance device which allows non‐invasive local measurements to a controlled depth. Close agreement between concentration and an irritation index calculated from electrical impedance parameters was found over the whole concentration range for most test persons‐ At concentrations below 0.2%, visual scores were zero. These results suggest that electrical impedance can ht; used as an objective tool to record irritation, and furl her that electrical impedance might be a more sensitive method than the commonly used visual readings.

Electrical impedance spectroscopy and the diagnostic accuracy for malignant melanoma

Abstract:  Background:  The accuracy of diagnosis of skin cancer and especially of early malignant melanoma is most important to reduce its morbidity and mortality. Previous pilot studies using electrical impedance measurements indicate statistically significant accuracies for the detection of skin cancer.

Baseline electrical impedance measurements at various skin sites - related to age and sex.

During previous studies on the electrical impedance of the skin, we formulated a set of four physical indices that could be used to distinguish between the cutaneous effects produced by different chemical irritants. We now employ the electrical impedance technique to compare the properties of different anatomical areas of the skin, using the same set of indices.

Non-invasive bioimpedance of intact skin: mathematical modeling and experiments

The functional integrity and pathology of the skin is reflected in its electrical impedance spectra. Non-invasive electrical impedance measurements of intact skin are dominated by the high impedic stratum corneum in low frequencies and with increasing frequency gradually comes to be dominated by viable skin. Models of this multi-layered organ can increase our understanding of the actual physical properties/dimensions and facilitate better diagnostics in certain applications. Therefore, a mathematical model considering conservation of charge in the various layers of the skin and adjacent electrodes is derived and validated with experimental findings; the latter was carried out on 60 young female subjects. The impact of the stratum corneum thickness, inundation, solvent and cohort size on the electrical properties is studied. Both model parameters and experimental conditions were adjusted for calibration and subsequent validation of the model with measurements. It is found that both the models thickness of the stratum corneum as well as experimental soaking conditions (both time and saline concentration) affect the fit between the model and measurements. It is concluded that it is essential that the electrical properties of the skin are presented in the context of the ion concentration (if a moisturizer is employed) as well as the soaking time. Further refinements should be made to determine even more accurate dielectrical properties of the stratum corneum and viable skin layers by accounting for the true skin thickness and the heterogeneity of the skin layers-this would be useful in applications where subtle alterations in the skin are of interest.

Electrical impedance index in human skin: measurements after occlusion, in 5 anatomical regions and in mi Id irritant contact dermatitis

The electrical impedance in 23 healthy volunteers at 2–6 different skin sites was measured with a new impedance device, which makes possible non‐invasive local measurements to a controlled depth. In 11 subjects, the lest sites were occluded for 24 h using empty Finn Chambers and chambers with water, physiological saline, a paper disc or 0.002% sodium lauryl sulfate (SI.S). In the normal skin of 10 subjects, the electrical impedance was measured from 5 different body areas for 5 consecutive days. In 3 subjects, daily measurements for I month were done, both from normal skin and from skin following the application of 2% SLS. The results show that the irritation index based on electrical skin impedance gives little day‐to‐day variation at one and the same lest site, in comparison to the variations between different test sites on the same subject and the inter individual variations observed. Significant differences in impedance values between different anatomical regions of normal skin were found. Occlusion does not affect readings taken 24 h or later alter removal, but increases variance for readings taken 1 after removal. Effects on the skin of mild irritation and its recovery phase are easily monitored wslh the new device. Technology based on electrical impedance, in ils newly presented form, with the advantages of improved geometrical dellnilinn and depth control, can be used as an objective tool to measure skin irritation. For detection of subclinical irritant contact dermatitis, repeated readings taken over several days may be needed.

Electrical impedance measurements at different skin sites related to seasonal variations.

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.