Assessing the Outcomes of Focused Heating of the Skin by a Long-Pulsed 1064 nm Laser with an Integrated Scanner, Infrared Thermal Guidance, and Optical Coherence Tomography.

Joseph N Mehrabi,Jon D Holmes,Christopher B Zachary,Kristen M Kelly

doi:10.1002/lsm.23377

Abstract

The skin on the forearm and back of two consenting volunteers was marked and anesthetized with lidocaine with epinephrine. The parameters of a scanner-equipped LP 1064 nm Nd:YAG laser were adjusted to achieve an epidermal/superficial dermal heating of between 50°C and 60°C over a specified time course. Experimental single treatments examined various adjusted parameters including, fluence, pulse overlap, pulse duration, scan size, and pulse rate. A FLIR camera was used to record skin temperature. Outcome measures included skin temperature, post-treatment appearance, and OCT assessment of skin and vascular damage. The clinical response of each treatment was followed daily for 4 weeks. Optimal protocols initially raised the skin temperature to between 55°C and 60°C, which was carefully maintained using subsequent laser passes over a 60-second time course. Immediately post laser, clinical responses included erythema, edema, and blistering. Immediate OCT revealed increased vascularity with intact, dilated blood vessels. Prolonged exposure above 60°C resulted in sub-epidermal blistering and an absence of blood flow in the treatment area with prolonged healing. The LP 1064 nm laser can be used to achieve heat-related tissue injury, though the narrow parameters necessary for the desired endpoint require the assistance of IR thermal regulation to avoid unacceptable outcomes. The use of the laser scanner ensures precise energy delivery over a defined treatment area. Future studies might explore this as a selective hyperthermic method for the treatment of non-melanoma skin cancer. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Highlights

There are multiple methods to induce thermal injury in the skin, including lasers, ultrasound, and radiofrequency
Multiple laser sessions were scheduled to test the various parameters of the scanner‐equipped LP Nd:YAG laser
The LP Nd:YAG laser emits energy at a wavelength of 1064 nm in the infrared portion of the electromagnetic spectrum allowing it to penetrate to the deeper dermis and below

Summary

Introduction

There are multiple methods to induce thermal injury in the skin, including lasers, ultrasound, and radiofrequency. Many of these are uncontrolled, potentially resulting in undesirable burns and subsequent scarring. Long‐term benefits can be predicted by the incorporation of more intelligent systems in lasers and other devices Such systems can produce more reliable zones of thermal injury when used in association with non‐invasive monitoring and precise laser energy delivery. The parameters of a scanner‐equipped LP 1064 nm Nd:YAG laser were adjusted to achieve an epidermal/superficial dermal heating of between 50°C and 60°C over a specified time course. Results: Optimal protocols initially raised the skin temperature to between 55°C and 60°C, which was carefully maintained using subsequent laser passes over a 60‐second time course.

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Discussion

Conclusion