Characterizing the tissue dielectric constant of skin basal cell cancer lesions.

BACKGROUND: Measuring tissue dielectric constant (TDC) of cancer tissues to distinguish them from normal or non-cancerous tissues has been an active area of research that has targeted several different cancer types usually using in vitro specimens. The goal of this study was to determine if and to what extent TDC values measured in vivo at 300 MHz using a simple hand-held measuring device might differentiate between skin cancer lesions and non-cancerous skin. MATERIALS AND METHODS: Triplicate TDC measurements were made in 32 patients who were subsequently diagnosed with skin basal cell carcinoma (BCC) and in 14 patients subsequently diagnosed as having non-cancerous lesions. Lesion TDC values were compared to contralateral unaffected skin and between lesion types. RESULTS: A significantly lower TDC value (mean ± SD) of BCC lesions (TDCL ) vs TDC values of contralateral non-affected skin (TDCC ) was found (22.4 ± 16.2 vs 38.1 ± 15.2, P < .00001). A similar pattern was found for non-cancerous lesions with lesion TDC values less than non-affected skin (14.5 ± 9.0 vs 29.1 ± 9.0, P < .0001). However, TDC values were not statistically different between BCC lesions and non-cancerous lesions (22.4 ± 16.2 vs 14.5 ± 9.0, P = .096) and calculated TDCL /TDCC ratios between BCC lesions and non-cancerous lesions also were not significantly different (0.596 ± 0.345 vs 0.501 ± 0.261, P = .364). CONCLUSIONS: (1) Main results do not support using TDC measurements to differentiate in vivo skin cancer lesions from non-cancerous lesions. (2) TDC values strongly suggest reduced water content of both cancerous and non-cancerous lesions. (3) Lesion TDC measurements provide reference values for future studies.

High-energy pulsed light source hair removal device used to evaluate the onset of action of a new topical anesthetic.

BACKGROUND: Topical anesthetic agents are widely used to mitigate the pain associated with laser and high-energy pulsed light source hair removal. OBJECTIVE: To evaluate the relative efficacy and onset of action of a new topical anesthetic agent, ELA-Max cream (lidocaine 4%), relative to a widely used agent, EMLA cream (lidocaine 2.5%/prilocaine 2.5%). METHODS: ELA-Max and EMLA were applied to the forearms of 10 unblinded test subjects. The EMLA-treated sites were occluded for 1.5 hours prior to testing. The ELA-Max-treated sites were unoccluded and the cream was applied immediately prior to testing. Pulses from an Epilight high-energy pulsed light source were then administered 1.5 hours after occlusion with EMLA and in 5-minute intervals after application of ELA-Max. Pain scores were recorded on a visual analog scale (VAS). RESULTS: Six of 10 patients reported some anesthetic effect from ELA-Max after 5 minutes of unoccluded skin contact. Seven of 10 subjects reported maximal pain control 20 minutes after application of unoccluded ELA-Max, roughly equivalent to EMLA after 1.5 hours of occlusion. CONCLUSION: ELA-Max is an effective topical anesthetic agent comparable to EMLA under occlusion. It appears to be faster acting than EMLA, and along with its effectiveness without occlusion, may be an easier agent to use.