Optimizing resection of brain metastatic lesions with intraoperative sodium fluorescein guidance

Background: Brain metastases are the most common intracranial tumors in adults and typically present as contrast-enhancing lesions on magnetic resonance imaging (MRI). Maximizing the extent of resection (EOR) is critical for achieving optimal oncological and functional outcomes. Intraoperative sodium fluorescein has been proposed as an adjunct to improve tumor visualization during resection. Methods: A prospective cohort study with a retrospective historical control group was conducted between 2023 and 2025, including 73 patients with histologically confirmed brain metastases. Fluorescein-guided resection was performed in 42 patients, while 31 patients underwent conventional microscopic resection. Sodium fluorescein (5 mg/kg) was administered intravenously after anesthesia induction. EOR was assessed using volumetric analysis of pre- and early postoperative contrast-enhanced MRI, and histopathological analysis was performed on fluorescent and non-fluorescent tissue samples. Results: Gross total resection was achieved in 95.3% of cases, with a mean EOR of 95.3% ± 3.99%. Fluorescein-guided surgery resulted in a significantly higher mean EOR compared with conventional microscopy (98.1% vs. 91.5%, P < 0.001). Sodium fluorescein demonstrated a sensitivity of 95.2% for identifying metastatic tumor tissue, with specificity reflecting the integration of fluorescence findings with anatomical knowledge and preoperative MRI correlation. One transient allergic reaction was reported and managed conservatively. Conclusion: Intraoperative sodium fluorescein is a safe and effective adjunct for the surgical resection of brain metastases, enabling improved tumor margin visualization and significantly increasing the EOR without compromising normal brain tissue.