1Department of Neurosurgery, University Hospital Göttingen.
2Paul-Flechsig Institute of Neuropathology, University Medical Center Leipzig; and.
J Neurosurg. 2022 Apr 29;137(6):1650-1655. doi: 10.3171/2022.3.JNS212301. Print 2022 Dec 1.
Fluorescence-guided resection of cerebral metastases has been proposed as an approach to visualize residual tumor tissue and maximize the extent of resection. Critics have argued that tumor cells at the resection margins might be overlooked under microscopic visualization because of technical limitations. Therefore, an endoscope, which is capable of inducing fluorescence, has been applied with the aim of improving exposure of fluorescent tumor tissue. In this retrospective analysis, authors assessed the utility of endoscope assistance in 5-aminolevulinic acid (5-ALA) fluorescence-guided resection of brain metastases.
Between June 2013 and December 2016, a standard 20-mg/kg dose of 5-ALA was administered 4 hours prior to surgery in 26 patients with suspected single brain metastases. After standard neuronavigated microsurgical tumor resection, a microscope capable of inducing fluorescence was used to examine tumor margins. The authors classified the remaining fluorescence into 3 grades (0 = none, 1 = weak, and 2 = strong). Endoscopic assistance was employed if no or only weak fluorescence was visualized at the resection margins under the microscope. Endoscopically identified fluorescent tissue at the margins was resected and evaluated separately via histological examination to prove or disprove tumor infiltration.
Under the microscope, weakly fluorescent tissue was seen at the margins of the resection cavity in 15/26 (57.7%) patients. In contrast, endoscopic inspection revealed strongly fluorescent tissue in 22/26 (84.6%) metastases. In 11/26 (42.3%) metastases no fluorescence at the tumor margins was detected by the microscope; however, strong fluorescence was visualized under the endoscope in 7 (63.6%) of these 11 metastases. In the 15 metastases with microscopically weak fluorescence, strong fluorescence was seen when using the endoscope. Neither microscopic nor endoscopic fluorescence was found in 4/26 (15.4%) cases. In the 26 patients, 96 histological specimens were obtained from the margins of the resection cavity. Findings from these specimens were in conjunction with the histopathological findings, allowing identification of metastatic infiltration with a sensitivity of 95.5% and a specificity of 75% using endoscope assistance.
Fluorescence-guided endoscope assistance may overcome the technical limitations of the conventional microscopic exposure of 5-ALA-fluorescent metastases and thereby increase visualization of fluorescent tumor tissue at the margins of the resection cavity with high sensitivity and acceptable specificity.
荧光引导切除脑转移瘤已被提出作为一种方法来观察残留肿瘤组织并最大限度地扩大切除范围。批评者认为，由于技术限制，在显微镜下观察时，可能会忽略肿瘤边缘的肿瘤细胞。因此，已经应用了一种能够诱导荧光的内窥镜，目的是提高荧光肿瘤组织的暴露度。在这项回顾性分析中，作者评估了内窥镜辅助在 5-氨基酮戊酸（5-ALA）荧光引导切除脑转移瘤中的应用。
在 2013 年 6 月至 2016 年 12 月期间，对 26 例疑似单发脑转移瘤的患者给予标准剂量的 20mg/kg 5-ALA，术前 4 小时给药。在标准的神经导航显微镜下肿瘤切除后，使用能够诱导荧光的显微镜检查肿瘤边缘。作者将剩余荧光分为 3 个等级（0 = 无，1 = 弱，2 = 强）。如果在显微镜下观察到切除边缘没有荧光或仅有微弱荧光，则采用内窥镜辅助。对显微镜下发现的弱荧光组织进行内镜下识别，并通过组织学检查单独评估，以证实或排除肿瘤浸润。
在显微镜下，15/26（57.7%）例患者的切除腔边缘可见弱荧光组织。相比之下，内窥镜检查显示 22/26（84.6%）的转移瘤有强荧光。在 11/26（42.3%）例患者中，显微镜下肿瘤边缘未检测到荧光，但在这 11 例中的 7 例（63.6%）转移瘤中，内窥镜下可见强荧光。在 15 例显微镜下弱荧光的转移瘤中，使用内窥镜可见强荧光。26 例患者中有 4 例（15.4%）显微镜和内窥镜均未见荧光。在 26 例患者中，从切除腔边缘获得了 96 个组织学标本。这些标本的检查结果与组织病理学检查结果一致，使用内窥镜辅助检查，检测肿瘤浸润的敏感性为 95.5%，特异性为 75%。
荧光引导内窥镜辅助检查可能克服了常规显微镜暴露 5-ALA-荧光转移瘤的技术限制，从而提高了切除腔边缘荧光肿瘤组织的可视化程度，具有较高的敏感性和可接受的特异性。
