Department of Neurosurgery, Hospital of the University of Pennsylvania, 235 South Eighth Street, Philadelphia, PA, 19106, USA.
Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
Mol Imaging Biol. 2018 Apr;20(2):213-220. doi: 10.1007/s11307-017-1107-5.
Distinguishing neoplasm from normal brain parenchyma intraoperatively is critical for the neurosurgeon. 5-Aminolevulinic acid (5-ALA) has been shown to improve gross total resection and progression-free survival but has limited availability in the USA. Near-infrared (NIR) fluorescence has advantages over visible light fluorescence with greater tissue penetration and reduced background fluorescence. In order to prepare for the increasing number of NIR fluorophores that may be used in molecular imaging trials, we chose to compare a state-of-the-art, neurosurgical microscope (System 1) to one of the commercially available NIR visualization platforms (System 2).
Serial dilutions of indocyanine green (ICG) were imaged with both systems in the same environment. Each system's sensitivity and dynamic range for NIR fluorescence were documented and analyzed. In addition, brain tumors from six patients were imaged with both systems and analyzed.
In vitro, System 2 demonstrated greater ICG sensitivity and detection range (System 1 1.5-251 μg/l versus System 2 0.99-503 μg/l). Similarly, in vivo, System 2 demonstrated signal-to-background ratio (SBR) of 2.6 ± 0.63 before dura opening, 5.0 ± 1.7 after dura opening, and 6.1 ± 1.9 after tumor exposure. In contrast, System 1 could not easily detect ICG fluorescence prior to dura opening with SBR of 1.2 ± 0.15. After the dura was reflected, SBR increased to 1.4 ± 0.19 and upon exposure of the tumor SBR increased to 1.8 ± 0.26.
Dedicated NIR imaging platforms can outperform conventional microscopes in intraoperative NIR detection. Future microscopes with improved NIR detection capabilities could enhance the use of NIR fluorescence to detect neoplasm and improve patient outcome.
在手术过程中区分肿瘤和正常脑组织对神经外科医生至关重要。5-氨基酮戊酸（5-ALA）已被证明可以提高肿瘤全切除率和无进展生存率，但在美国的可用性有限。近红外（NIR）荧光具有比可见光荧光更大的组织穿透深度和更低的背景荧光的优势。为了为可能用于分子成像试验的越来越多的 NIR 荧光团做好准备，我们选择将最先进的神经外科显微镜（系统 1）与一种市售的近红外可视化平台（系统 2）进行比较。
在相同环境下，使用两种系统对吲哚菁绿（ICG）的连续稀释液进行成像。记录和分析了每个系统对 NIR 荧光的灵敏度和动态范围。此外，还使用两种系统对来自六名患者的脑肿瘤进行了成像和分析。
在体外，系统 2 显示出更高的 ICG 灵敏度和检测范围（系统 1 为 1.5-251μg/l，系统 2 为 0.99-503μg/l）。同样，在体内，系统 2 在打开硬脑膜前的信号与背景比（SBR）为 2.6±0.63，打开硬脑膜后为 5.0±1.7，暴露肿瘤后为 6.1±1.9。相比之下，系统 1 在打开硬脑膜前很难检测到 ICG 荧光，SBR 为 1.2±0.15。硬脑膜反射后，SBR 增加到 1.4±0.19，肿瘤暴露后 SBR 增加到 1.8±0.26。
专用近红外成像平台在术中近红外检测方面可以优于传统显微镜。具有改进的近红外检测能力的未来显微镜可以增强使用近红外荧光检测肿瘤的能力，并改善患者的预后。
