Saccomandi P, Quero G, Costamagna G, Diana M, Marescaux J
Annu Int Conf IEEE Eng Med Biol Soc. 2017 Jul;2017:4533-4536. doi: 10.1109/EMBC.2017.8037864.
Endoscopic submucosal dissection (ESD) is a minimally invasive technique allowing for the removal of early gastrointestinal (GI) tumors, widely considered as a valid alternative to conventional surgery. However, ESD is technically demanding, and potentially severe complications, such as bleeding and perforation, may occur. Energy-based techniques (e.g., radiofrequency ablation) might offer a potential alternative to ESD. However, their use mandates the ability to predict the damage induced and to identify a "signature" of the complete ablation, without the need for a physical specimen. Ideally, an energy-based procedure should be tunable in order to limit the ablation to the superficial layers, namely mucosa (M) and submucosa (SM), without injuring the muscularis propria (MP), thereby minimizing GI perforation. This experimental study aims to investigate thermal damage induced by Nd:YAG laser on the gastric wall, at different laser settings such as power (P) and time (t). Laser ablation was performed on the stomach wall of 6 Wistar rats. Two powers (2.5W and 1.0W) and 3 exposure times (12s, 6s and 2s) were tested, for a total of 30 ablations. Histological analysis allowed to assess thermal damage, in terms of damage depth (DD) and identification of involved layers. The ratio (R) between DD and the total depth (TD) of target layers (M+SM) was used as an index to evaluate the effectiveness of laser settings. At P=2.5W, MP was damaged (R>1) in the majority of cases (11/15). At P=1.0W, MP was preserved in all tests (R<;1), and rarely (4/15) did the damage reach the whole SM (R=1). Histopathological analysis evidenced that tissue damage was strongly related to the variable tissue thickness. These preliminary results seem to support the fact that endoscopic tunable laser ablation is feasible with a consistent damage/power correlation. Further tests are required to optimize the settings for applications on early GI tumors.
内镜黏膜下剥离术（ESD）是一种微创技术，可用于切除早期胃肠道（GI）肿瘤，被广泛认为是传统手术的有效替代方法。然而，ESD技术要求较高，可能会出现诸如出血和穿孔等严重并发症。基于能量的技术（如射频消融）可能为ESD提供一种潜在的替代方法。然而，使用这些技术需要能够预测所诱导的损伤并识别完全消融的“特征”，而无需物理标本。理想情况下，基于能量的手术应具有可调性，以便将消融限制在表层，即黏膜（M）和黏膜下层（SM），而不损伤固有肌层（MP），从而将胃肠道穿孔的风险降至最低。本实验研究旨在探究不同激光参数（如功率（P）和时间（t））下钕钇铝石榴石（Nd:YAG）激光对胃壁造成的热损伤。对6只Wistar大鼠的胃壁进行了激光消融。测试了两种功率（2.5W和1.0W）和3种照射时间（12秒、6秒和2秒），共进行了30次消融。组织学分析用于评估热损伤的深度（DD）以及所涉及的层次。DD与目标层次（M+SM）总深度（TD）的比值（R）用作评估激光参数有效性的指标。在功率P = 2.5W时，大多数情况下（11/15）固有肌层受到损伤（R>1）。在功率P = 1.0W时，所有测试中固有肌层均得以保留（R<1），且很少（4/15）出现损伤累及整个黏膜下层的情况（R = 1）。组织病理学分析表明，组织损伤与组织厚度的变化密切相关。这些初步结果似乎支持了内镜可调激光消融在损伤与功率具有一致相关性方面是可行的这一事实。还需要进一步测试以优化早期胃肠道肿瘤应用的参数设置。
