Assessing Electrical Impedance Dermography as a Tool in Skin Disease Management and Diagnosis

Electrical impedance dermography (EID) is a useful tool for diagnosing and assessing skin conditions and assisting in various dermatological applications, according to a review published in Dermatology Research and Practice.¹

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Background and Methods

EID utilizes principles of electrical impedance to assess skin properties. The technique involves applying alternating electrical current to the skin and measuring the resulting voltage changes, while simultaneously relying on the interaction of the electrical current with the skin's ionic and cellular structures.²

Previous research has explored its utility in various skin cancers. For example, a 2023 study published in JID Innovations reported EID was capable of discerning nonmelanoma skin cancer, squamous cell carcinoma in situ, from one of its benign mimickers, inflamed seborrheic keratoses.³ EID has also been used to analyze and characterize basal cell carcinoma.⁴

Authors of the present review, Brunsgaard et al, sought to assess EID in the clinical context of dermatology to further examine the evolution of devices used to measure electrical impedance.

Findings

Electrical impedance data obtained from EID can be used to infer skin's conductivity and relative permittivity. Both conductivity and relative permittivity properties vary with frequency and can be affected by changes in the skin’s structure and composition due to disease.

EID measurements can be conducted using various electrode setups, including a 2-electrode setup, 3-electrode setup, and 4-electrode setup. The first iteration measures impedance but includes contributions from skin-electrode polarization impedance, while the most advanced iteration utilizes separate pairs of electrodes for current application and voltage measurement.

Different electrode types, such as wet and dry electrodes, and minimally invasive designs, affect the measurement quality and accuracy. Wet electrodes generally provide the best contact but can irritate the skin, while dry and minimally invasive electrodes offer less irritation and better spatial resolution.

EID has shown potential in clinical settings for diagnosing skin conditions, demonstrating the capability to differentiate between skin cancers and benign conditions, with devices like Nevisense demonstrating high sensitivity in identifying melanoma and nonmelanoma skin cancers.

While some studies reported high specificity for melanoma, reviewers reported that differentiation between basal cell carcinomas and other types of skin cancer remains challenging. EID has limitations in distinguishing between benign conditions and malignant skin cancers due to overlapping impedance characteristics.

The review also yielded evidence that the use of EID in clinical practice has shown benefits in improving biopsy decision-making. Studies have demonstrated that EID can enhance diagnostic accuracy of skin cancers and reduce unnecessary biopsies.

At present, several EID devices have been developed with varying features, including SCIM; TransScan; SciBase I, I, and III; Nevisense; and URSKIN.

Conclusions

"Given the promising findings of studies using electrical impedance-based techniques, EID has demonstrated potential as an adjunct skin cancer screening tool, a reliable method to assess treatment response in atopic dermatitis, a clinical research device to study transdermal drug delivery, and a measurement tool to assist in sunscreen formulation," according to Brunsgaard et al.

Reviewers suggested that future research into EID and its utility in dermatology be inclusive of larger datasets. Additionally, they noted that measurement techniques and new machine learning analytics should first be further developed.

References

1. Brunsgaard EK, Sanchez B, Grossman D. Electrical impedance dermography: background, current state, and emerging clinical opportunities. Dermatol Res Pract. August 16, 2024. https://doi.org/10.1155/2024/2085098
2. Rutkove SB, Sanchez B. Electrical impedance methods in neuromuscular assessment: an overview. Cold Spring Harb Perspect Med. 2019;9(10):a034405. October 1, 2019. doi:10.1101/cshperspect.a034405
3. Wen-Ying Wong E, Pandeya S, Crandall H, et al. Electrical impedance dermography differentiates squamous cell carcinoma in situ from inflamed seborrheic keratoses. JID Innov. 2023;3(3):100194. February 20, 2023. doi:10.1016/j.xjidi.2023.100194
4. Lou X, Zhou Y, Smart T, Grossman D, Sanchez B. Electrical characterization of basal cell carcinoma using a handheld electrical impedance dermography device. JID Innov. January 2022. https://doi.org/10.1016/j.xjidi.2021.100075