Introduction: Different fluorophores (fluorescent biomarkers) including 5-ALA have been recently examined for maximizing the extent of resection for high-grade gliomas. Since 5-ALA is not approved by FDA, regulatory barriers have significantly limited its use. Herein, a new practical safe method for fluorescence-guided resection of gliomas will be presented using an FDA approved agent (low-dose sodium fluorescein.)
Methods: Following IRB approval, low-dose (300mg) sodium fluorescein was injected in 6 consecutive patients with presumed diagnosis of a glioma intravenously 10-20 minutes before resection of the tumor. A high definition filter (Yellow 560, Zeiss Meditech, Oberkochen, Germany) integrated onto the operating microscope was used to intensify and assess the degree of fluorescent signal between the tumor and normal surrounding brain. We conducted histopathalogical examination of the areas of maximal and minimal fluorescence to assess the authenticity of the fluorescent signal in demonstrating infiltrative glioma cells.
Results: Upon injection of the fluorecein, the entire brain and vessels fluoresced immediately, however within minutes, the normal structures cleared fluorescein but all the tumors in all patients remained intensely stained with fluorescein and clearly demarcated from surrounding normal brain as confirmed based on neuronavigation data. This low dose fluorescein fluorescence was not detectable by an unaided eye. Thirty histopathological sections were obtained at tumor margins and assessed for presence of glioma cells. Twenty-six sections corresponded correctly to the degree of fluorescence observed in surgery. In four sections, although minor amount of fluorescence was present intraoperatively, more than 50% of the specimens contained viable tumor cells. Overall, presence of major fluorescence was 100% sensitive and 90% specific for presence of tumors cells.
In one patient, the lack of fluorescence correctly confirmed the diagnosis of a non-nepolastic inflammatory lesion. This method of fluorescence was easy to use and did not interfere with operating room workflow. Miniscule leakage of fluorescein in the blood of the surgical field did not interfere with tumor fluorescence.
Conclusions: Intravenous low-dose fluorescein provides a readily available method for fluorescence-guided tumor resection. It can improve resection of gliomas with minimal risks. Further studies are necessary to establish the efficacy of this technique in affecting patients’ survival.
Patient Care: Maximize glioma resection.
Learning Objectives: By the conclusion of the session, participants will be able to discuss the importance of fluorescence in glioma resection, assess the importance of fluorescine in glioma resection and explain the details of the present techniques.