Improved Availability of Fluorescence-Guided Surgery of Malignant Brain Tumors: A Headlamp-Loupe System Combined With Generic 5-Aminolevulinic Acid Replaces the Microscope-A Monocentric Feasibility Study

OBJECTIVE: Until recently, a prerequisite for fluorescence-guided surgery (FGS) was the use of a specialized microscope. With the availability of a system that combines surgical loupes with an FGS-enabled headlamp, the standard approach to FGS of gliomas is challenged. We therefore investigated the potential change in practice of FGS for gliomas, if the surgeon had the choice between both systems. METHODS: Patients with a lesion indicating FGS were included. Surgery was performed by 3 specialized neurooncological neurosurgeons, who were provided with a headlamp-loupe system (HLLS) (5-aminolevulinic acid headlamp and surgeon-adapted loupes, 3.5X, customized fitted). We recorded surgeons' choice between HLLS and microscope and semi-quantified the statements. Additionally, in one case, specificity and sensitivity of various protoporphyrin IX (PpIX) fluorescence (PpIX-f) were histopathologically evaluated. RESULTS: We report 206 procedures in 198 patients. Surgeons opted in 194 (94%) of the cases for HLLS and did not switch from HLLS to microscope in any case. Three biopsies taken from areas with negative, faint, and highly positive PpIX-f, as revealed by the HLLS but not by the microscope, corresponded to normal brain tissue (negative PpIX-f), infiltration zone (faint PpIX-f), and highly cellular tumor tissue with microvascular proliferation (strong PpIX-f). CONCLUSIONS: Our center changed the practice of FGS by switching from microscopes to loupes. The reported experience might have an important impact on the general use and availability of FGS, as the HLLS and the in-house preparation of 5-aminolevulinic acid come at a fraction of the costs of the commonly practiced approach.