Bedi Vikramaditya P, Chan Kin Foong, Sink R Kehl, Hantash Basil M, Herron G Scott, Rahman Zakia, Struck Steven K, Zachary Christopher B
Reliant Technologies, Inc., Mountain View, California 94043, USA.
Lasers Surg Med. 2007 Feb;39(2):145-55. doi: 10.1002/lsm.20406.
We examined the effects of pulse energy variations on the dimensions of microscopic thermal injury zones (MTZs) created on human skin ex vivo and in vivo using nonablative fractional resurfacing.
A Fraxel SR laser system emitting at 1,550 nm provided an array of microscopic spots at variable densities. Pulse energies ranging from 4.5 to 40 mJ were tested on human abdominal skin ex vivo and in vivo. Tissue sections were stained with hematoxylin and eosin (H&E) or nitro blue tetrazolium chloride (NBTC) and MTZ dimensions were determined. Ex vivo and in vivo results were compared. Dosimetry analyses were made for the surface treatment coverage calculation as a function of pulse energy and collagen coagulation based on H&E stain or cell necrotic zone based on NBTC stain.
Each MTZ was identified by histological detection of a distinct region of loss of tissue birefringence and hyalinization, representing collagen denaturation and cell necrosis within the irradiated field immediately, 1, 3, and 7 days after treatment. At high pulse energies, the MTZ depth could exceed 1 mm and width approached 200 microm as assessed by H&E. NBTC staining revealed viable interlesional tissue. In general, no statistically significant difference was found between in vivo and ex vivo depth and width measurements.
The Fraxel SR laser system delivers pulses across a wide range of density and energy levels. We determined that increases in pulse energy led to increases in MTZ depth and width without compromising the structure or viability of interlesional tissue.
我们研究了脉冲能量变化对使用非剥脱性分次激光表面重建技术在离体和活体人皮肤上形成的微观热损伤区（MTZ）尺寸的影响。
一台发射波长为1550 nm的飞梭SR激光系统提供了一系列密度可变的微观光斑。在离体和活体的人腹部皮肤上测试了范围为4.5至40 mJ的脉冲能量。组织切片用苏木精和伊红（H&E）或氯化硝基四氮唑蓝（NBTC）染色，并测定MTZ尺寸。比较了离体和活体的结果。基于H&E染色的胶原蛋白凝固或基于NBTC染色的细胞坏死区，对表面治疗覆盖率作为脉冲能量的函数进行了剂量学分析。
通过组织学检测到组织双折射丧失和透明化的不同区域来识别每个MTZ，这分别代表治疗后即刻、1天、3天和7天照射区域内的胶原蛋白变性和细胞坏死。通过H&E评估，在高脉冲能量下，MTZ深度可能超过1 mm，宽度接近200微米。NBTC染色显示病变间组织存活。总体而言，如果发现活体和离体的深度及宽度测量值之间没有统计学上的显著差异。
飞梭SR激光系统可在广泛的密度和能量水平上发射脉冲。我们确定，脉冲能量的增加导致MTZ深度和宽度增加，而不会损害病变间组织的结构或活力。
