In vivo dual-axis confocal microscopy of 5-ALA-induced PpIX to guide low-grade glioma resections

总结 切除范围与胶质瘤患者的预后相关，如无进展生存期。图像- 基于MRI和现在的荧光引导手术（FGS）的引导技术已经发展到 提高外科医生观察肿瘤边缘的能力。然而，有基本的限制， 宽视野成像方法如MRI和FGS等检测播散性肿瘤细胞的敏感性差 在弥漫性胶质瘤的浸润边缘，以及图像的非定量和主观性质， 解释。随着使用5-ALA的FGS的出现，以及FDA最近在2017年的批准， 低级别胶质瘤（LGG）和高级别胶质瘤（HGG）患者之间，就切除范围而言， 可能加宽，因为LGG很少产生足够的PpIX荧光以通过宽场FGS检测。 因此，显然需要改进的术中技术，其具有检测和治疗肿瘤的灵敏度。 量化肿瘤腔边缘的残留LGG，以提高切除范围和延迟 复发我们已经表明，高分辨率共聚焦显微镜具有可视化稀疏的敏感性， 用5-ALA治疗的LGG患者中PpIX的亚细胞表达，甚至超过放射学边缘。 因此，我们将优化一个手持光学切片显微镜，以成像5-ALA诱导的PpIX在最后 LGG患者的切除边缘，以及实时视频拼接，以促进大的成像 组织区域，这将在对异质脑组织成像时最大限度地减少采样偏差（目标1）。为了 为了促进这些技术的临床接受，我们将建立显微镜之间的关系， PpIX表达模式和已确立的生物学指标，如肿瘤负荷和增殖指数 (Aim 2）。最后，我们将探讨假设，定量显微成像PpIX的切除 切缘可预测切除范围，如目前术后MRI所定义，这表明， 它对于优化切除以最小化和/或延迟复发（目标3）具有价值。总的来说，这些结果 将为未来的随机对照临床研究铺平道路，以优化切除手术和结局 对于LGG患者（成人和儿童），其中许多人可以有良好的生存结果和生活质量。

Summary Extent-of-resection is correlated with glioma patient outcomes such as progression-free survival. Image- guidance technologies, based on MRI and now fluorescence-guided surgery (FGS), have been developed to improve the surgeon’s ability to visualize gross tumor margins. However, there are fundamental limitations to wide-field imaging methods such as MRI and FGS, such as poor sensitivity to detect disseminated tumor cells at the infiltrative margins of diffuse gliomas, as well as the non-quantitative and subjective nature of image interpretation. With the emergence of FGS using 5-ALA, and its recent approval by the FDA in 2017, the gap between low-grade glioma (LGG) and high-grade glioma (HGG) patients, in terms of extent of resection, will likely widen since LGGs rarely generate sufficient PpIX fluorescence to be detected via wide-field FGS. Consequently, there is a clear need for improved intraoperative techniques with the sensitivity to detect and quantify residual LGGs at the margins of the tumor cavity in order to improve the extent of resection and delay recurrence. We have shown that high-resolution confocal microscopy has the sensitivity to visualize the sparse sub-cellular expression of PpIX in LGG patients treated with 5-ALA, even beyond the radiographic margins. Therefore, we will optimize a handheld optical-sectioning microscope to image 5-ALA-induced PpIX at the final resection margins in LGG patients, together with real-time video mosaicking to facilitate the imaging of large tissue areas, which will minimize sampling bias when imaging heterogeneous brain tissues (Aim 1). In order to facilitate the clinical acceptance of these techniques, we will establish a relationship between the microscopic patterns of PpIX expression and well-established biological metrics such as tumor burden and proliferative index (Aim 2). Finally, we will explore the hypothesis that quantitative microscopic imaging of PpIX of the resection margins is predictive of extent of resection, as currently defined by post-operative MRI, which would suggest that it has value for optimizing resections to minimize and/or delay recurrence (Aim 3). Collectively, these results will pave the way for future randomized controlled clinical studies to optimize resection procedures and outcomes for LGG patients (adults and children), many of whom can have good survival outcomes and quality of life.