Editorial: Applications of Fluorescence in Surgery and Diagnostics, Volume II: Evolution and Breakthroughs

Evgenii Belykh¹Mark Preul^2*

• ¹Rutgers University Newark, Newark, United States
• ²Division of Neurological Surgery, Barrow Neurological Institute (BNI), Phoenix, Arizona, United States

fluorophores, such as 5-aminolevulinic acid, fluorescein sodium, and indocyanine green and the rapid emergence of cellular-resolution imaging, artificial intelligence-assisted interpretation, and novel molecular probes that address unmet clinical needs (Fig. 1). Neurosurgical technology use is rapidly expanding to optimize surgical resection of invasive brain tumors. Chen et al. [1] present real-world clinical evidence supporting fluorescein-guided surgery for resecting high-grade gliomas in "Fluorescein-guided surgery for high-grade glioma resection: a five-year-long retrospective study at our institute." They found that fluorescein guidance was associated with higher gross total resection rates and lower postoperative residual tumor volumes, without increasing operative time, blood loss, or complication rates. For tumors in noneloquent regions, such as the temporal and occipital lobes, fluorescein sodium was a practical and accessible adjunct to standard microsurgical workflows. Xu et al. [2] address the critical question of who can reliably interpret intraoperative confocal laser endomicroscopy (CLE) images in "Intraoperative in vivo confocal endomicroscopy of the glioma margin: performance assessment of image interpretation by neurosurgeon users." They showed that neurosurgeons performed comparably to neuropathologists when interpreting CLE images at glioma margins, supporting CLE as a practical intraoperative guidance tool. Validating a simple dichotomous scoring system further enhances its feasibility for real-time use during surgery.Brielmaier et al. [3] investigate the biological basis of fluorescein staining patterns observed during brain tumor CLE in "Fluorescein-distribution in confocal laser endomicroscopy allows for discrimination between primary brain tumours and metastases." Their combined in vitro, ex vivo, and in vivo analyses reveal tumor entity-specific intracellular fluorescein accumulation, enabling discrimination between primary brain tumors and metastatic lesions. This work highlights how fluorophore-tissue interactions enhance diagnostic interpretation beyond mere signal presence.Artificial intelligence (AI) is rapidly progressing in fluorescence imaging assessment.Chen and colleagues [4] introduce a sequence-based artificial intelligence model that incorporates temporal information from CLE image streams, mimicking expert human interpretation in "Artificial intelligence prediction of nonenhancing brain tumor malignancy based on in vivo confocal laser endomicroscopic imaging." Their approach outperforms frame-based models and achieves diagnostic accuracy comparable to that of neuropathologists. This study demonstrates that AI can reduce subjectivity, enhance specificity, and support intraoperative decision-making in the management of these tumors. Xu et al. [5] examine and assess the growing body of clinical evidence supporting CLE use in neurosurgery in "Clinical application of confocal laser endomicroscopy in neurosurgery: a scoping review." CLE demonstrates diagnostic performance comparable to frozen-section pathology across multiple platforms and fluorophores, with faster feedback and seamless workflow integration. The authors emphasize the need for prospective interventional trials to define CLE's impact on surgical outcomes.Zhang and colleagues [6] reported the extension of fluorescence guidance beyond neurooncology in "A preliminary investigation of precise visualization, localization, and resection of pelvic lymph nodes in bladder cancer by using indocyanine green fluorescence-guided approach through intracutaneous dye injection into the lower limbs and perineum." They conceptualized a novel intracutaneous ICG injection strategy for pelvic lymph node mapping in bladder cancer. Shimizu at al. [10] review the rapidly evolving landscape of fluorescent aminopeptidase probes, including HMRG-and 2MeSiR-based agents, with a focus on neurosurgical applications in "Advancement of fluorescent aminopeptidase probes for rapid cancer detection-current uses and neurosurgical applications." They detail how these probes provide enzyme-activated, tumorspecific fluorescence and rapid signal generation as an alternative to metabolism-based contrast agents such as 5-ALA. This work highlights the shift in molecular probe design to higher specificity and cellular-level functional imaging. Xu and colleagues [11] demonstrate a novel application of fluorescein sodium as a marker of focused ultrasound-induced blood-brain barrier disruption in "Fluorescein sodium as a marker for focused ultrasound-induced blood-brain barrier disruption: a case report in a porcine model." They correlate macroscopic and microscopic fluorescence findings with contrastenhanced MRI and histology to assess real-time blood-brain-barrier permeability, with implications for drug delivery and intraoperative diagnostics.Collectively, the articles in this volume illustrate how fluorescence-guided surgery and diagnostics are advancing synergistic developments in molecular probes, imaging platforms, interpretive frameworks, and computational tools. As these technologies mature, interdisciplinary collaboration will be essential to translate innovation into improved patient outcomes. Large-scale patient trials are necessary to demonstrate the practical utility of these techniques and to influence improved surgical outcomes and patient survival. This collection contributes to that effort, capturing the current state of the field and pointing to its future.