Fractional ablative erbium YAG laser: Histological characterization of relationships between laser settings and micropore dimensions

TY - JOUR

T1 - Fractional ablative erbium YAG laser

T2 - Histological characterization of relationships between laser settings and micropore dimensions

AU - Taudorf, Elisabeth H

AU - Haak, Christina S

AU - Erlendsson, Andrés M

AU - Philipsen, Peter A

AU - Anderson, R Rox

AU - Paasch, Uwe

AU - Haedersdal, Merete

N1 - © 2014 Wiley Periodicals, Inc.

PY - 2014/4

Y1 - 2014/4

N2 - Background and Objectives Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940nm AFXL using a variety of stacked pulses, and determines a model correlating laser parameters with tissue effects. Materials and Methods Ex vivo pig skin was exposed to a miniaturized 2,940nm AFXL, spot size 225μm, density 5%, power levels 1.15-2.22W, pulse durations 50-225microseconds, pulse repetition rates 100-500Hz, and 2, 20, or 50 stacked pulses, resulting in pulse energies of 2.3-12.8mJ/microbeam and total energy levels of 4.6-640mJ/microchannel. Histological endpoints were ablation depth (AD), coagulation zone (CZ) and ablation width (AW). Data were logarithmically transformed if required prior to linear regression analyses. Results for histological endpoints were combined in a mathematical model. Results In 138 sections from 91 biopsies, AD ranged from 16 to a maximum of 1,348μm and increased linearly with the logarithm of total energy delivered by stacked pulses, but also depended on variations in power, pulse duration, pulse repetition rate, and pulse energy (r2=0.54-0. 85, P<0.0001). Microchannels deeper than 500μm were created only by the highest pulse energy of 12.8mJ/microbeam. Pulse stacking increased AD, and enlarged CZ and AW. CZ varied from 0 to 205μm and increased linearly with total energy (r2=0.56-0.75, P<0.0001). AW ranged from 106 to 422μm and increased linearly with the logarithm of number of stacked pulses (r2=0.53-0.61, P<0.001). The mathematical model estimated micropores of specific ADs with an associated range of CZs and AWs, for example, 300μm ADs were associated with CZs from 27 to 73μm and AWs from 190 to 347μm. Conclusions Pulse stacking with a small, low power 2,940nm AFXL created reproducible shallow to deep micropores, and influenced micropore configuration. Mathematical modeling established relations between laser settings and micropore dimensions, which assists in choosing laser settings for desired tissue effects.

AB - Background and Objectives Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940nm AFXL using a variety of stacked pulses, and determines a model correlating laser parameters with tissue effects. Materials and Methods Ex vivo pig skin was exposed to a miniaturized 2,940nm AFXL, spot size 225μm, density 5%, power levels 1.15-2.22W, pulse durations 50-225microseconds, pulse repetition rates 100-500Hz, and 2, 20, or 50 stacked pulses, resulting in pulse energies of 2.3-12.8mJ/microbeam and total energy levels of 4.6-640mJ/microchannel. Histological endpoints were ablation depth (AD), coagulation zone (CZ) and ablation width (AW). Data were logarithmically transformed if required prior to linear regression analyses. Results for histological endpoints were combined in a mathematical model. Results In 138 sections from 91 biopsies, AD ranged from 16 to a maximum of 1,348μm and increased linearly with the logarithm of total energy delivered by stacked pulses, but also depended on variations in power, pulse duration, pulse repetition rate, and pulse energy (r2=0.54-0. 85, P<0.0001). Microchannels deeper than 500μm were created only by the highest pulse energy of 12.8mJ/microbeam. Pulse stacking increased AD, and enlarged CZ and AW. CZ varied from 0 to 205μm and increased linearly with total energy (r2=0.56-0.75, P<0.0001). AW ranged from 106 to 422μm and increased linearly with the logarithm of number of stacked pulses (r2=0.53-0.61, P<0.001). The mathematical model estimated micropores of specific ADs with an associated range of CZs and AWs, for example, 300μm ADs were associated with CZs from 27 to 73μm and AWs from 190 to 347μm. Conclusions Pulse stacking with a small, low power 2,940nm AFXL created reproducible shallow to deep micropores, and influenced micropore configuration. Mathematical modeling established relations between laser settings and micropore dimensions, which assists in choosing laser settings for desired tissue effects.

KW - Animals

KW - Biopsy

KW - Dermatologic Surgical Procedures

KW - Female

KW - In Vitro Techniques

KW - Lasers, Solid-State

KW - Linear Models

KW - Skin

KW - Swine

U2 - 10.1002/lsm.22228

DO - 10.1002/lsm.22228

M3 - Journal article

C2 - 24500855

SN - 0196-8092

VL - 46

SP - 281

EP - 289

JO - Lasers in Surgery and Medicine

JF - Lasers in Surgery and Medicine

IS - 4

ER -