Analysis of an electrical impedance spectroscopy system in short-term digital dermoscopy imaging of melanocytic lesions

Abstract

Background

Electrical impedance spectroscopy (EIS) is a non-invasive diagnostic technique that measures tissue impedance.

Objectives

This prospective study, conducted at 2 centres in Australia, aimed to evaluate the effect of adding an EIS measurement at baseline to suspicious melanocytic lesions undergoing routine short-term sequential digital dermoscopy imaging (SDDI)

Methods

Patients presented with suspicious melanocytic lesions that were eligible for short-term SDDI (with no clear feature of melanoma on dermoscopy). The EIS measurement was performed at the first visit following the dermoscopic photography. Normally, an EIS score of ≥4 is considered positive whereas this protocol investigated a higher cut-off in combination with SDDI. When the EIS score was ≥7 the lesion was excised immediately due to the high risk of melanoma. Lesions with a score <7 were monitored with standard SDDI over a 3 month period.

Results

From a total of 160 lesions analysed, 128 of 154 benign lesions received an EIS score of 0-6, giving a specificity of the EIS method for the diagnosis of melanoma of 83.1% (95% CI:76.3-88.7). Five of the six melanomas found in this study had an EIS score ≥7, with a sensitivity for melanoma diagnosis of 83.3% (95% CI:35.9-99.6).

When EIS 0-6 lesions were subsequently followed up with SDDI, one additional melanoma was detected (EIS=6) giving the sensitivity for the diagnosis of melanoma overall of 100%: 95% CI:54.1-100 (6/6 MM excised) and the specificity 69.5%: 95% CI:61.5 to 76.6 (107/154 benign lesions not excised).

Conclusion

If utilizing a protocol where an EIS score ≤3 requires no SDDI and ≥7 requires immediate excision this reduced the need for SDDI by 46.9% (75/160): 95% CI:39.0-54.9.

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