Stelzle Florian, Knipfer Christian, Bergauer Bastian, Rohde Maximilian, Adler Werner, Tangermann-Gerk Katja, Nkenke Emeka, Schmidt Michael
Department of Oral and Maxillofacial Surgery, Friedrich-Alexander-University, Erlangen-Nuremberg, Glückstrasse 11, 91054, Erlangen, Germany,
Lasers Med Sci. 2014 Sep;29(5):1641-8. doi: 10.1007/s10103-014-1569-5. Epub 2014 Apr 3.
Facial nerve function may be hampered by iatrogenic damage during head and neck laser surgery procedures. Optical techniques can serve as a basis for feedback-controlled tissue-specific laser surgery on the jaw bone and the parotid gland. In order to preserve nerve tissue during laser surgery, the alteration of optical tissue properties through laser-tissue interactions have to be taken into account. It was the aim of this study to evaluate the viability of optical tissue differentiation through diffuse reflectance spectroscopy after exposure to laser light as a basis for a feedback system for tissue-specific laser surgery. Spectra of diffuse reflectance (wavelength, 350-650 nm) of nerves, salivary glands, and cortical and cancellous bone of the midfacial region (ex vivo domestic pig heads) were acquired before/after Er:YAG laser (wavelength, 2.94 μm) ablation (each 16,800 spectra). Principal component analysis was computed followed by quadratic discriminant analysis. The tissue classification performance as well as area under the curve (AUC) sensitivity and specificity for tissue differentiation was assessed before and after laser-tissue exposure. A high classification performance was observed before laser ablation (total error, 7.74%). Nerve tissue was differentiated from bone and salivary glands with results greater than 0.96 in AUC, sensitivity and specificity. After laser exposure, a total classification error of 18.61% was observed. The differentiation of nerve tissue was reduced with an AUC of >0.94, sensitivity of >0.95, and specificity >0.87. Er:YAG laser ablation only slightly reduces the differentiation performance through diffuse reflectance in the investigated tissue types. The results show the general viability of diffuse reflectance spectroscopy in identifying neural structures in the vicinity of salivary glands and bone as a basis for nerve preservation during feedback-controlled laser surgery.
在头颈部激光手术过程中，面神经功能可能会受到医源性损伤。光学技术可作为对颌骨和腮腺进行反馈控制的组织特异性激光手术的基础。为了在激光手术中保护神经组织，必须考虑激光与组织相互作用引起的光学组织特性变化。本研究的目的是评估激光照射后通过漫反射光谱进行光学组织区分的可行性，以此作为组织特异性激光手术反馈系统的基础。在铒钇铝石榴石（Er:YAG）激光（波长2.94μm）消融前后（各采集16800个光谱），获取了面中部区域（离体家猪头）的神经、唾液腺以及皮质骨和松质骨的漫反射光谱（波长350 - 650nm）。进行主成分分析，随后进行二次判别分析。在激光与组织相互作用前后，评估了组织分类性能以及用于组织区分的曲线下面积（AUC）敏感性和特异性。在激光消融前观察到较高的分类性能（总误差7.74%）。神经组织与骨和唾液腺得以区分，AUC、敏感性和特异性结果均大于0.96。激光照射后，观察到总分类误差为18.61%。神经组织的区分能力有所下降，AUC>0.94，敏感性>0.95，特异性>0.87。在研究的组织类型中，Er:YAG激光消融仅略微降低了通过漫反射进行的区分性能。结果表明，漫反射光谱在识别唾液腺和骨附近的神经结构方面具有普遍可行性，可作为反馈控制激光手术中神经保护的基础。
