Bergauer Bastian, Knipfer Christian, Amann Andreas, Rohde Maximilian, Tangermann-Gerk Katja, Adler Werner, Schmidt Michael, Nkenke Emeka, Stelzle Florian
Department of Oral and Maxillofacial Surgery, Friedrich-Alexander University Erlangen-Nuremberg (FAU), Erlangen 91054, Germany.
Bavarian Laser Center GmbH (blz), Erlangen 91054, Germany.
Sensors (Basel). 2015 Oct 1;15(10):25416-32. doi: 10.3390/s151025416.
The protection of sensitive structures (e.g., nerves) from iatrogenic damage is of major importance when performing laser surgical procedures. Especially in the head and neck area both function and esthetics can be affected to a great extent. Despite its many benefits, the surgical utilization of a laser is therefore still limited to superficial tissue ablation. A remote feedback system which guides the laser in a tissue-specific way would provide a remedy. In this context, it has been shown that nerval structures can be specifically recognized by their optical diffuse reflectance spectra both before and after laser ablation. However, for a translation of these findings to the actual laser ablation process, a nerve protection within the laser pulse is of utmost significance. Thus, it was the aim of the study to evaluate, if the process of Er:YAG laser surgery--which comes with spray water cooling, angulation of the probe (60°) and optical process emissions--interferes with optical tissue differentiation. For the first time, no stable conditions but the ongoing process of laser tissue ablation was examined. Therefore, six different tissue types (nerve, skin, muscle, fat, cortical and cancellous bone) were acquired from 15 pig heads. Measurements were performed during Er:YAG laser ablation. Diffuse reflectance spectra (4500, wavelength range: 350-650 nm) where acquired. Principal component analysis (PCA) and quadratic discriminant analysis (QDA) were calculated for classification purposes. The clinical highly relevant differentiation between nerve and bone was performed correctly with an AUC of 95.3% (cortial bone) respectively 92.4% (cancellous bone). The identification of nerve tissue against the biological very similar fat tissue yielded good results with an AUC value of 83.4% (sensitivity: 72.3%, specificity: of 82.3%). This clearly demonstrates that nerve identification by diffuse reflectance spectroscopy works reliably in the ongoing process of laser ablation in spite of the laser beam, spray water cooling and the tissue alterations entailed by tissue laser ablation. This is an essential step towards a clinical utilization.
在进行激光外科手术时，保护敏感结构（如神经）免受医源性损伤至关重要。特别是在头颈部区域，功能和美观都会受到很大程度的影响。尽管激光有诸多益处，但其外科应用仍局限于浅表组织消融。一种以组织特异性方式引导激光的远程反馈系统可能会提供解决方案。在这种情况下，已经表明神经结构在激光消融前后都可以通过其光学漫反射光谱被特异性识别。然而，要将这些发现转化为实际的激光消融过程，在激光脉冲内保护神经至关重要。因此，本研究的目的是评估掺铒钇铝石榴石（Er:YAG）激光手术过程（包括喷水冷却、探头成角（60°）和光学过程发射）是否会干扰光学组织分化。首次研究的不是稳定条件，而是正在进行的激光组织消融过程。因此，从15个猪头获取了六种不同的组织类型（神经、皮肤、肌肉、脂肪、皮质骨和松质骨）。在Er:YAG激光消融过程中进行测量。获取了漫反射光谱（4500，波长范围：350 - 650 nm）。为了进行分类，计算了主成分分析（PCA）和二次判别分析（QDA）。神经与骨之间临床高度相关的区分分别以95.3%（皮质骨）和92.4%（松质骨）的曲线下面积（AUC）正确进行。神经组织与生物学上非常相似的脂肪组织的识别取得了良好结果，AUC值为83.4%（敏感性：72.3%，特异性：82.3%）。这清楚地表明，尽管有激光束、喷水冷却以及组织激光消融引起的组织变化，但通过漫反射光谱识别神经在正在进行的激光消融过程中可靠地起作用。这是迈向临床应用的重要一步。
