Analysis of Nd:YAG laser-mediated thermal damage in rabbit nasal septal cartilage
Analysis of Nd:YAG laser-mediated thermal damage in rabbit nasal septal cartilage
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DOI：
10.1002/lsm.20514
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发表时间：
2007-06-01
影响因子：
2.4
通讯作者：
Wong, Brian
中科院分区：
文献类型：
--
作者：
Li, Chao;Protsenko, Dmitry E.;Wong, Brian
背景和目的：激光软骨重塑(LCR)是一种利用光热加热对软骨进行重塑的技术。它的临床相关性取决于将受照射区域的热损伤降至最低的能力。研究设计/材料与方法：用波长为1.32µm、光斑直径5.4 mm的激光照射兔鼻中隔软骨，照射时间分别为4、6、8、10、12、16秒，功率分别为4、6、8、10、12和8W，用红外热像仪采集照射区域软骨表面的温度，通过速率过程模型预测组织损伤。采用活/死活性测定和荧光共聚焦显微镜相结合的方法测量受照标本的热损伤程度。结果：当激光重塑参数达到或低于激光重塑参数时，发生了相当大的热损伤，而激光重塑参数产生了临床上相关的形状变化。激光功率密度和曝光时间分别为4W和6s时，共聚焦显微镜下可见横截面厚度为500微米左右的软骨标本上有大量死亡细胞，损伤程度随时间和照射时间的延长而增加。速率过程模型的损伤预测与测量数据吻合较好。结论：这些结果表明，显著的热损伤与临床相关的形状变化是同时存在的。这与以前的观念相矛盾，即存在一个与临床相关的形状变化和组织存活共存的特权激光剂量学参数。
Background and Objectives: Laser cartilage reshaping (LCR) involves the use of photo-thermal heating to reshape cartilage. Its clinical relevance depends on the ability to minimize thermal injury in irradiated regions. The present study seeks to understand the safety of LCR by determining shape change and resultant tissue viability as a function of laser dosimetry.Study Design/Materials and Methods: Rabbit nasal septal cartilage were irradiated using a Nd:YAG laser (lambda = 1.32 mu m, 5.4 mm spot diameter) with different exposure times of 4, 6, 8, 10, 12, and 16 seconds and powers of 4, 6, and 8 W. Temperature on the cartilage surface in the laser-irradiated region was collected using infrared thermography, this data was then used to predict tissue damage via a rate process model. A Live/Dead viability assay combined with fluorescent confocal microscopy was used to measure the amount of thermal damage generated in the irradiated specimens.Results: Considerable thermal injury occurred at and below the laser-reshaping parameters that produced clinically relevant shape change using the present Nd:YAG laser. Confocal microscopy identified dead cells spanning the entire cross-sectional thickness of the cartilage specimen (about 500 mu m thick) at laser power density and exposure times above 4 W and 6 seconds; damage increased with time and irradiance. The damage predictions made by the rate process model compared favorably with measured data.Conclusions: These results demonstrate that significant thermal damage is concurrent with clinically relevant shape change. This contradicts previous notions that there is a privileged laser dosimetry parameter where clinically relevant shape change and tissue viability coexist.