Kim Changhwan, Park Hoyong, Lee Ho
School of Mechanical Engineering, Kyungpook National University, Daegu, 702-701, Korea.
Lasers Surg Med. 2013 Sep;45(7):437-49. doi: 10.1002/lsm.22155. Epub 2013 Jul 12.
Laser-assisted lipoplasty is made possible by using an optical fiber that delivers light endoscopically to subcutaneous fat tissue. Most optical fibers for laser-assisted lipoplasty are designed to be irradiated in a forward direction. In this study, we compared forward-firing fiber and diffusing fiber for use in laser-assisted lipoplasty. The effective parameters of the ablation pattern which resulted from the laser-induced damage are discussed for both systems. In particular, we note the effect resulting from the different beam emission patterns and the contours of laser fluence.
We used two different laser delivery systems (a forward-firing fiber and a diffusing fiber) to examine how the beam emission pattern affects the laser-assisted coagulation and damage pattern of in vitro fat tissues. A porcine liver tissue (water-rich tissue) was used as a secondary laser target to investigate how the laser-assisted coagulation pattern depends on both the type of tissue (water-rich and lipid-rich tissue) as well as the delivery system. An evaluation using a digital camera and a thermal camera was conducted for the tissue ablation processes in order to observe the generated heat transfer in fat and liver.
The overall shape of the laser-assisted coagulation zone was different from the beam emission pattern in the case where a forward-firing fiber was used within fat tissue. The center of the laser-affected zone is characterized by the formation of a reservoir of melted fat. In the thermal image analysis, there existed a discrepancy between the temperature distribution of the fat tissue and the liver tissue during the forward-firing fiber irradiation. In the liver tissue ablation process, the temperature distribution during the laser ablation also demonstrated an elongated ellipse that matches well with the laser-induced damage zone. The temperature distribution in fat tissue adhered to a more discoid pattern that corresponded to the laser-induced damage zone.
Based on our findings, we have proposed mechanisms that can explain the laser-induced damage in both tissues when a forward firing fiber is employed as the delivery system. In the case of fat tissue, the ablation mechanism can be characterized by the reservoir formation of melted lipids while the ablation is characterized as the well-known drilling effect for liver tissue.
通过使用可将光经内镜传输至皮下脂肪组织的光纤，激光辅助脂肪抽吸术得以实现。大多数用于激光辅助脂肪抽吸术的光纤设计为向前照射。在本研究中，我们比较了用于激光辅助脂肪抽吸术的向前发射光纤和扩散光纤。讨论了两种系统因激光诱导损伤而产生的消融模式的有效参数。特别地，我们注意到不同光束发射模式和激光能量密度轮廓所产生的影响。
我们使用两种不同的激光传输系统（向前发射光纤和扩散光纤）来研究光束发射模式如何影响体外脂肪组织的激光辅助凝固和损伤模式。使用猪肝组织（富水组织）作为次要激光靶点，以研究激光辅助凝固模式如何取决于组织类型（富水和富脂组织）以及传输系统。为观察脂肪和肝脏中产生的热传递，对组织消融过程进行了数码摄像机和热成像摄像机评估。
在脂肪组织中使用向前发射光纤的情况下，激光辅助凝固区的整体形状与光束发射模式不同。激光影响区的中心特征是形成了一个融化脂肪池。在热图像分析中，向前发射光纤照射期间脂肪组织和肝脏组织的温度分布存在差异。在肝脏组织消融过程中,激光消融期间的温度分布也呈现出一个细长的椭圆形，与激光诱导损伤区吻合良好。脂肪组织中的温度分布呈现出更接近盘状的模式，与激光诱导损伤区相对应。
基于我们的研究结果，我们提出了一些机制，这些机制可以解释当使用向前发射光纤作为传输系统时两种组织中激光诱导的损伤。在脂肪组织的情况下，消融机制的特征是融化脂质形成池，而对于肝脏组织，消融的特征是众所周知的钻孔效应。
