Sodium Fluorescein-Guided Resection under the YELLOW 560 nm Surgical Microscope Filter in Malignant Gliomas: Our First 38 Cases Experience

Relationship between the sodium fluorescein yellow fluorescence boundary and the actual boundary of high-grade gliomas during surgical resection

OBJECTIVE

Resection of high-grade glioma with sodium fluorescein can improve the resection rate of the glioma and improve survival. However, it is unclear whether the yellow fluorescence boundary of the high-grade glioma is consistent with the actual boundary of the tumor. This study explores the yellow fluorescence boundary and the actual tumor boundary in high-grade glioma surgery.

METHODS

This is a retrospective analysis of 10 patients with high-grade gliomas who underwent tumor visualization with sodium fluorescein. After staining of the tumor, random selections of both developed and non-developed yellow fluorescent border tissue at the fluorescence chromogenic boundary were made, followed by pathological examination. Claudin-5, an important component of the tight connections between vascular endothelial cells, was assessed by immunohistochemistry and qRT-PCR in the tumor and surrounding tissues in order to determine the tumor cell content of the tissue, blood-brain barrier damage, and vascular proliferation. The yellow fluorescence boundary was compared with the actual tumor boundary and the results analyzed.

RESULTS

Tumor cells were still detected outside the yellow fluorescence boundary during high-grade glioma surgery (P <  0.05). Claudin-5 expression was higher in high-grade gliomas than in adjacent normal tissues (P < 0.05), while disconnected Claudin-5 expression was associated with intraoperative yellow fluorescence imaging (r = 0.67).

CONCLUSIONS

There is a difference between the yellow fluorescence boundary and the actual boundary of the tumor in high-grade glioma, and there are glioma cell infiltrations in the brain tissue of the undeveloped yellow fluorescent border. To ensure patient recovery and function, it is recommended that tumor resection be expanded based on yellow fluorescence visualization. Claudin-5 is overall up-regulated in high-grade gliomas, but some Claudin-5 expression is disconnected. This Claudin-5 expression pattern may be related to the development of yellow fluorescence.

A light in the darkness: sodium fluorescein-assisted peripheral nerve sheath tumors resection - a comprehensive systematic review and single-arm meta-analysis

The treatment for peripheral nerve sheath tumors (PNSTs) is based on surgical excision and the primary goal is to improve symptoms whilst preserving neurological function. In order to improve this technique, surgeons may use sodium fluorescein (SF) to help visualize the neoplasm and, consequently, facilitate its removal. Aiming to assess the efficacy of this emerging surgical strategy, we conducted a systematic review and single-arm meta-analysis. We conducted a systematic search on the PubMed, Embase, and Web of Science databases, following the PRISMA guidelines. Studies without outcomes of interest, case series with less than four patients, letters, comments, technical notes, editorials, reviews, and basic research papers were excluded. The outcomes considered for this study were: the number of tumors that achieved total resection, subtotal resection, or near total resection, the approach/technique utilized by the surgeon, SF-related complications, and total complications. Five studies, with a total of 175 individuals, were included in our survey. Notably, 70% of the neoplasms presented by the patients were schwannomas. Considering extracranial lesions, we found a proportion of 96% (95% CI: 88 - 100%) in total resection, 0% (95% CI: 0-1%) in near total resection, and 4% (95% CI: 0-12%) in subtotal resection, all linked to an amount of 185 analyzed PNSTs. Furthermore, a proportion of 1% (95% CI: 0 - 2%) in SF-related complications was spotted among 183 patients. Finally, total complications analysis accounted for 11% (95% CI: 0 - 25%) among 183 individuals. We concluded that SF-assisted resection of PNSTs is a suitable and relatively safe technique, linked to minimum complications, of which the majority was not associated with the chemical compound itself. Future research is necessary to increase the number of patients available in the current literature and, therefore, enhance future analyses.

Confocal laser endomicroscopy in glial tumors-a histomorphological analysis

OBJECTIVE

The extent of resection and neurological outcome are important prognostic markers for overall survival in glioma patients. Confocal laser endomicroscopy is a tool to examine tissue without the need for fixation or staining. This study aims to analyze gliomas in confocal laser endomicroscopy and identify reliable diagnostic criteria for glial matter and glial tumors.

MATERIAL AND METHODS

One-hundred-and-five glioma specimens were analyzed using a 670-nm confocal laser endomicroscope and then processed into hematoxylin-eosin-stained frozen sections. All confocal images and frozen sections were evaluated for the following criteria: presence of tumor, cellularity, nuclear pleomorphism, changes of the extracellular glial matrix, microvascular proliferation, necrosis, and mitotic activity. Recurring characteristics were identified. Accuracy, sensitivity, specificity, and positive and negative predictive values were assessed for each feature.

RESULTS

All 125 specimens could be processed and successfully analyzed via confocal laser endomicroscopy. We found diagnostic criteria to identify white and grey matter and analyze cellularity, nuclear pleomorphism, changes in the glial matrix, vascularization, and necrosis in glial tumors. An accuracy of > 90.0 % was reached for grey matter, cellularity, and necrosis, > 80.0 % for white matter and nuclear pleomorphism, and > 70.0 % for microvascular proliferation and changes of the glial matrix. Mitotic activity could not be identified. Astroglial tumors showed significantly less nuclear pleomorphism in confocal laser endomicroscopy than oligodendroglial tumors (p < 0.001). Visualization of necrosis aids in the differentiation of low grade gliomas and high grade gliomas  (p < 0.002).

CONCLUSION

Autofluorescence-based confocal laser endomicroscopy proved not only useful in differentiation between tumor and brain tissue but also revealed useful clues to further characterize tissue without processing in a lab. Possible applications include the improvement of extent of resection and the safe harvest of representative tissue for histopathological and molecular genetic diagnostics.

A Wearable Fluorescence Imaging Device for Intraoperative Identification of Human Brain Tumors

Malignant glioma (MG) is the most common type of primary malignant brain tumors. Surgical resection of MG remains the cornerstone of therapy and the extent of resection correlates with patient survival. A limiting factor for resection, however, is the difficulty in differentiating the tumor from normal tissue during surgery. Fluorescence imaging is an emerging technique for real-time intraoperative visualization of MGs and their boundaries. However, most clinical grade neurosurgical operative microscopes with fluorescence imaging ability are hampered by low adoption rates due to high cost, limited portability, limited operation flexibility, and lack of skilled professionals with technical knowledge. To overcome the limitations, we innovatively integrated miniaturized light sources, flippable filters, and a recording camera to the surgical eye loupes to generate a wearable fluorescence eye loupe (FLoupe) device for intraoperative imaging of fluorescent MGs. Two FLoupe prototypes were constructed for imaging of Fluorescein and 5-aminolevulinic acid (5-ALA), respectively. The wearable FLoupe devices were tested on tumor-simulating phantoms and patients with MGs. Comparable results were observed against the standard neurosurgical operative microscope (PENTERO® 900) with fluorescence kits. The affordable and wearable FLoupe devices enable visualization of both color and fluorescence images with the same quality as the large and expensive stationary operative microscopes. The wearable FLoupe device allows for a greater range of movement, less obstruction, and faster/easier operation. Thus, it reduces surgery time and is more easily adapted to the surgical environment than unwieldy neurosurgical operative microscopes. Clinical and Translational Impact Statement-The affordable and wearable fluorescence imaging device developed in this study enables neurosurgeons to observe brain tumors with the same clarity and greater flexibility compared to bulky and costly operative microscopes.

Intraoperative MR Imaging during Glioma Resection

One of the major issues in the surgical treatment of gliomas is the concern about maximizing the extent of resection while minimizing neurological impairment. Thus, surgical planning by carefully observing the relationship between the glioma infiltration area and eloquent area of the connecting fibers is crucial. Neurosurgeons usually detect an eloquent area by functional MRI and identify a connecting fiber by diffusion tensor imaging. However, during surgery, the accuracy of neuronavigation can be decreased due to brain shift, but the positional information may be updated by intraoperative MRI and the next steps can be planned accordingly. In addition, various intraoperative modalities may be used to guide surgery, including neurophysiological monitoring that provides real-time information (e.g., awake surgery, motor-evoked potentials, and sensory evoked potential); photodynamic diagnosis, which can identify high-grade glioma cells; and other imaging techniques that provide anatomical information during the surgery. In this review, we present the historical and current context of the intraoperative MRI and some related approaches for an audience active in the technical, clinical, and research areas of radiology, as well as mention important aspects regarding safety and types of devices.

Fluorescein-Guided Resection of High Grade Gliomas: A Meta-Analysis

BACKGROUND

High-grade gliomas (HGGs) have a poor prognosis despite current standard of care of surgery, chemotherapy, and radiation therapy. Achieving gross total resection (GTR) has been found to prolong survival in these patients. Intraoperative fluorescent agents are often used to aid in the resection of HGGs. One commonly used fluorescent agent is fluorescein sodium, which is U.S. Food and Drug Administration-approved for ocular surgeries and has a better side effect profile and is less costly than 5-aminolevulinic acid (5-ALA). In this meta-analysis, we provide statistical evidence of the efficacy in using fluorescein for HGG resection.

METHODS

Following the PRISMA framework, we assessed 119 reports from PubMed, Medline (Ovid), and BIOSIS Citation Index and found 21 eligible studies for meta-analysis, assessing the rates of GTR with fluorescein-guided resection of HGGs.

RESULTS

A pooled cohort of 336 patients underwent fluorescein-guided HGG resection with a GTR rate of 81% (95% confidence interval 73%-89%; P < 0.001). Ten case-controlled studies were analyzed, showing a 29.5% increase in GTR rate in the fluorescein group compared with non-fluorescein-guided surgeries.

CONCLUSIONS

This meta-analysis shows that fluorescein-guided surgery improves GTR rates of HGGs when compared with non-fluorescence guided surgery and has similar GTR rates when compared with reported 5-ALA-guided resection rates.

Resection of intra- and paraventricular malignant brain tumors using fluorescein sodium-guided neuroendoscopic transtubular approach

BACKGROUND

The requirement of brain retraction and difficulty in distinguishing the tumor demarcation are challenging in conventional approaches to intra- and paraventricular malignant tumors (IV-PVMTs). Tubular retractors can minimize the retraction injury, and fluorescein-guided (FG) surgery may promote the resection of tumors. Our aim is to evaluate the feasibility, safety, and effectiveness of fluorescein-guided endoscopic transtubular surgery for the resection of IV-PVMTs.

METHODS

Twenty patients with IV-PVMTs underwent FG endoscopic transtubular tumor resection. Fluorescein sodium was administered before the dural opening. The intraoperative fluorescence staining was classified as "helpful" and "unhelpful" based on surgical observation. Extent of resection was assessed using postoperative magnetic resonance imaging. Karnofsky Performance Status (KPS) score was used to evaluate the general physical condition of patients.

RESULTS

There were 9 glioblastomas, 4 anaplastic astrocytomas and 7 metastatic tumors. "Helpful" fluorescence staining was observed in 16(80%) of 20 patients. Gross total resection was achieved in 16(80%) cases, near-total in 3(15%) cases, and subtotal in 1 (5%) case. No intra- or postoperative complications related to the fluorescein sodium occurred. The median preoperative KPS score was 83, and the median KPS score 3-month after surgery was 88.

CONCLUSION

FG endoscopic transtubular surgery is a feasible technique for the resection of IV-PVMTs. It may be a safe and effective option for patients with these tumors. Future prospective randomized studies with larger samples are needed to confirm these preliminary data.

Comprehensive review of surgical microscopes: technology development and medical applications

SIGNIFICANCE

Surgical microscopes provide adjustable magnification, bright illumination, and clear visualization of the surgical field and have been increasingly used in operating rooms. State-of-the-art surgical microscopes are integrated with various imaging modalities, such as optical coherence tomography (OCT), fluorescence imaging, and augmented reality (AR) for image-guided surgery.

AIM

This comprehensive review is based on the literature of over 500 papers that cover the technology development and applications of surgical microscopy over the past century. The aim of this review is threefold: (i) providing a comprehensive technical overview of surgical microscopes, (ii) providing critical references for microscope selection and system development, and (iii) providing an overview of various medical applications.

APPROACH

More than 500 references were collected and reviewed. A timeline of important milestones during the evolution of surgical microscope is provided in this study. An in-depth technical overview of the optical system, mechanical system, illumination, visualization, and integration with advanced imaging modalities is provided. Various medical applications of surgical microscopes in neurosurgery and spine surgery, ophthalmic surgery, ear-nose-throat (ENT) surgery, endodontics, and plastic and reconstructive surgery are described.

RESULTS

Surgical microscopy has been significantly advanced in the technical aspects of high-end optics, bright and shadow-free illumination, stable and flexible mechanical design, and versatile visualization. New imaging modalities, such as hyperspectral imaging, OCT, fluorescence imaging, photoacoustic microscopy, and laser speckle contrast imaging, are being integrated with surgical microscopes. Advanced visualization and AR are being added to surgical microscopes as new features that are changing clinical practices in the operating room.

CONCLUSIONS

The combination of new imaging technologies and surgical microscopy will enable surgeons to perform challenging procedures and improve surgical outcomes. With advanced visualization and improved ergonomics, the surgical microscope has become a powerful tool in neurosurgery, spinal, ENT, ophthalmic, plastic and reconstructive surgeries.

Fluorescein-guided resection of gliomas

Standard of care in the management of high-grade gliomas includes gross total resection (GTR) followed by treatment with radiation and temozolomide. GTR remains one of the few independent prognostic factors for improved survival in this disease. Sodium fluorescein is an organic fluorophore that has been studied as a surgical adjunct to improve the likelihood of achieving GTR in gliomas. Though sodium fluorescein does not selectively accumulate in glioma cells, it allows for real-time identification of regions of blood brain barrier breakdown, corresponding to the contrast-enhancing cores of high-grade gliomas. In addition to its high predictive value for identifying pathologic tissue, use of fluorescein has been shown to improve rates of GTR. In stereotactic needle biopsies, it helps reduce procedure time by rapidly confirming the presence of diagnostic tissue. Furthermore, in non-enhancing, low-grade gliomas, it labels focal regions of vascular dysregulation that have been correlated with high-grade features. Fluorescein has also been shown to be significantly less expensive than other contemporary surgical adjuncts such as intraoperative ultrasound, intraoperative MRI, and the recently FDA approved fluorophore, 5-aminolevulinic acid (5-ALA). Here, we review the current literature on the effectiveness of fluorescein as a surgical tool in the resection of gliomas.

NOVEL USE OF FLUORESCEIN DYE IN DETECTION OF ORAL DYSPLASIA AND ORAL CANCER

BACKGROUND

India is now regarded as the country with one of the highest incidence of oral cancer in the world. Considering poor survival in cases with late diagnosis, early detection can reduce morbidity and mortality of cancer patients and may impede malignant transformation in cases of oral potentially malignant disorders (OPMD). Most of the diagnostic aids are expensive and not available for mass screenings in developing countries. There is a need to develop a sensitive and affordable technique for screening of oral cancer, which can be accurate even in hands of health care workers with limited experience. Fluorescein dye has been used for tumour detection in colon, stomach, breast and brain. However, its utility in the diagnosis of oral cancer and OPMD has not yet been explored.

METHODS

This is the first study to report the role of fluorescein in the detection of oral cancer and OPMD. The present cross sectional study was conducted at a tertiary care dental centre. It included 100 individuals presenting with 42 OPMDs, 40 oral squamous cell carcinoma (OSCC) and 18 controls.

RESULTS

The sensitivity and specificity for the fluorescein detection method for OPMDs and OSCC was found to be 96.6% and 52.4% respectively. The positive predictive value was 73.7% and the negative predictive value was 91.7% for the fluorescein method. The likelihood ratios stood at 2.03 for a positive test and 0.066 for a negative test.

CONCLUSION

We conclude that fluorescein staining along with blue light is likely to improve detection of early oral cancers and dysplasia and can play a vital role in mass screening programmes of oral cancer.

Sodium Fluorescein in Brain Tumor Surgery: Assessing Relative Fluorescence Intensity at Tumor Margins

Purpose

The use of intraoperative 5-aminolevulinic acid fluorescence has been shown to increase the extent of resection in high-grade glioma surgery. Sodium fluorescein is an alternate fluorescence agent with advantages of low cost, low adverse effect profile, and ability to visualize anatomical detail under the fluorescence filter. Sodium fluorescein-based fluorescence is not specific to tumor cells, and the significance of residual fluorescence at tumor margins has been questioned. In this article, the authors sought to correlate fluorescence intensity at tumor margins with the presence of residual contrast-enhancing tumor on magnetic resonance imaging (MRI).

Methods

Eleven patients with a total of 12 lesions were enrolled in the study. Sodium fluorescein was administered at a dose of 5 mg/kg on induction of anesthesia. Relative intensity of fluorescence was extrapolated from intraoperative photographs through isolation of the green channel from the red/green/blue image, then graphically representing of pixel intensity through application of a thermal map. The correlation between areas of avid fluorescence at tumor cavity margins and the presence of residual contrast-enhancing tumor on postoperative MRI was evaluated.

Results

All tumors demonstrated fluorescence. The presence of avid fluorescence at tumor cavity margins had a sensitivity of 66.7% and specificity of 75% for the presence of residual contrast-enhancing tumor on postoperative MRI. There were no adverse effects of fluorescein administration.

Conclusion

Quantification of relative fluorescence intensity allows easy identification of areas that are high risk for residual contrast-enhancing tumor. Graphical representation of green pixel intensity requires validation through histopathological analysis but has the potential for real-time clinical application.

Sodium fluorescein shows high surgeon-reported usability in glioblastoma surgery

INTRODUCTION

Glioblastoma has a high mortality rate. Current treatment includes largest possible surgical resection of the tumour using neuronavigation and fluorescence to better identify tumour tissue. In recent years, sodium fluorescein has been reintroduced in neurosurgery as a fluorescence to increase the resection rate. In this study we aimed to measure the surgeons experience of using sodium fluorescein to locate and remove tumour tissue. Furthermore we describe a case of sodium fluorescein tissue distribution.

MATERIAL AND METHODS

13 patients with glioblastoma and seven patients with cerebral metastases undergoing surgical resection were included. Surgery was performed using microscope alternating between white light and the YELLOW 560 filter, which visualized sodium fluorescein. Surgeons graded its usability in terms of location and removal on a scale from one to four. The resection rate was determined by neuroradiologists. Tissue samples obtained during surgery were analysed in relation to fluorescence and dysmorphic cells.

RESULTS

Surgeons reported high usability in terms of location and removal of tumours using sodium fluorescein with medians of four in all groups, except for sub-total resections which had a median of three. Surgical complications were minimal and both resection rate and survival rate was within international standards. Histological analysis showed a visual correlation between tumorous tissue and intensity of fluorescence.

CONCLUSION

Sodium fluorescence is an effective and useful tool for surgeons during fluorescence-guided surgery for the resection of glioblastoma and cerebral metastases.

T2 Fluid-Attenuated Inversion Recovery Resection for Glioblastoma Involving Eloquent Brain Areas Facilitated Through Awake Craniotomy and Clinical Outcome

BACKGROUND

Despite evidence that a greater extent of resection (EOR) improves survival, the role of extended resection based on magnetic resonance imaging (MRI) fluid-attenuated inversion recovery (FLAIR) in the prognosis of glioblastoma (GBM) remains controversial. This study aims to investigate the role of additional resection of FLAIR-detected abnormalities and its influence on clinical outcomes of patients with GBM.

METHODS

Forty-six patients with newly diagnosed GBM involving eloquent brain areas were included. Surgeries were performed using awake craniotomy (AC) or AC combined with sodium fluorescein (SF) guidance. Following total removal of the contrast-enhancing tumor area, the EOR of FLAIR abnormalities was dichotomized to identify the best separation threshold for progression-free survival (PFS), overall survival (OS), and 30-day postoperative neurologic function of patients with GBM.

RESULTS

The threshold for removal of FLAIR abnormalities affecting survival was determined to be 25%. The median OS and PFS were shorter in the group with FLAIR resection <25% compared with the group with FLAIR resection ≥25% (12 months vs. 26 months; P = 0.001 and 6 months vs. 15 months; P = 0.016, respectively). Univariate and multivariate analyses identified tumor location within or near the eloquent brain areas and the 25% threshold for FLAIR EOR as independent factors affecting OS and PFS.

CONCLUSIONS

Identifying a feasible threshold for the resection of FLAIR abnormalities is valuable in improving the survival of patients with GBM. Extended resection of GBM involving eloquent brain areas was safe when using a combination of AC and SF-guided surgery.

Intraoperative fluorescence diagnosis in the brain: a systematic review and suggestions for future standards on reporting diagnostic accuracy and clinical utility

Background

Surgery for gliomas is often confounded by difficulties in distinguishing tumor from surrounding normal brain. For better discrimination, intraoperative optical imaging methods using fluorescent dyes are currently being explored. Understandably, such methods require the demonstration of a high degree of diagnostic accuracy and clinical benefit. Currently, clinical utility is determined by tissue biopsies which are correlated to optical signals, and quantified using measures such as sensitivity, specificity, positive predictive values, and negative predictive values. In addition, surgical outcomes, such as extent of resection rates and/or survival (progression-free survival (PFS) and overall survival (OS)) have been measured. These assessments, however, potentially involve multiple biases and confounders, which have to be minimized to ensure reproducibility, generalizability and comparability of test results. Test should aim at having a high internal and external validity. The objective of this article is to analyze how diagnostic accuracy and outcomes are utilized in available studies describing intraoperative imaging and furthermore, to derive recommendations for reliable and reproducible evaluations.

Methods

A review of the literature was performed for assessing the use of measures of diagnostic accuracy and outcomes of intraoperative optical imaging methods. From these data, we derive recommendations for designing and reporting future studies.

Results

Available literature indicates that potential confounders and biases for reporting the diagnostic accuracy and usefulness of intraoperative optical imaging methods are seldom accounted for. Furthermore, methods for bias reduction are rarely used nor reported.

Conclusions

Detailed, transparent, and uniform reporting on diagnostic accuracy of intraoperative imaging methods is necessary. In the absence of such reporting, studies will not be comparable or reproducible. Future studies should consider some of the recommendations given here.

Electronic supplementary material

The online version of this article (10.1007/s00701-019-04007-y) contains supplementary material, which is available to authorized users.

Surgery of malignant motor-eloquent gliomas guided by sodium-fluorescein and navigated transcranial magnetic stimulation: a novel technique to increase the maximal safe resection

BACKGROUND

Maximal safe resection is the goal of modern surgical treatment of high-grade gliomas (HGGs) located close to the motor cortex (M1) and/or the corticospinal tract (CST). Preoperative planning based on navigated transcranial magnetic stimulation (nTMS) and fluorescence-guided resection (FGR) using sodium-fluorescein have been separately described to increase the extent of resection (EOR) while preserving the motor pathway. We assessed the efficacy of the combination of these techniques for surgery of motor-eloquent HGGs.

METHODS

We enrolled patients with motor-eloquent HGGs operated at the Departments of Neurosurgery of the University of Messina, Italy, and of the Charitè Universitatsmedizin Berlin, Germany, between 2016 and 2019. All patients underwent nTMS mapping of M1, and nTMS-based DTI tractography of CST. Tumor resection was guided by intraoperative neurophysiological mapping (IONM) supported by sodium-fluorescein fluorescence and by intraoperative visualization of the nTMS-based information through neuronavigation. EOR and new permanent motor deficits were compared with a historical control group of patients operated exclusively with IONM guidance.

RESULTS

Seventy-nine patients were enrolled, while 55 patients were included as controls. The gross total resection (GTR) rate was significantly higher in patients operated using nTMS + FGR compared with controls (64.5% vs. 47.2%, P=0.04). As well, postoperative new permanent motor deficits were reduced in the study group vs. controls (11.4% vs. 20%).

CONCLUSIONS

In this series, the combination of sodium-fluorescein FGR with nTMS-based planning improved surgical treatment of motor-eloquent HGGs. It represents a valuable support to IONM-guided resection, increasing the GTR rate while reducing the occurrence of permanent motor deficits.

Molecular pathological expression in malignant gliomas resected by fluorescein sodium-guiding under the YELLOW 560 nm surgical microscope filter

Background

This study aimed to analyze the relationship between molecular pathologic expression of GFAP and Ki-67 and fluorescence levels, and to provide molecular pathological basis for the removal of malignant gliomas (MG) by Fluorescein Sodium (FLS) navigation under the YELLOW 560 nm surgical microscope filter.

Methods

A retrospective analysis of clinical data of 18 MG cases confirmed by the postoperative pathology was performed. All cases were resected by FLS guiding under the YELLOW 560 nm filter. Hematoxylin-eosin (HE) staining, molecular pathology markers GFAP, and Ki-67 immunohistochemical staining of the specimens were performed. The relationship between fluorescence staining levels and GFAP positive rate, Ki-67 proliferation index, and WHO grades was studied.

Results

There were 69 pathological specimens with fluorescence levels of “bright” fluorescence (n = 32), “low” fluorescence (n = 18), and “no” fluorescence (n = 19). Immunohistochemical staining showed GFAP-positive expression in both tumor cells and normal glial cells. The staining levels of the specimens in the fluorescence regions were higher than that in the non-fluorescence regions. GFAP expression was positive in 61 specimens and negative in 8 specimens. Comparison of Ki-67 proliferation index using chi-square test showed different fluorescence levels had different Ki-67 proliferation indexes (χ² = 14.678, p = 0.005). With high proliferation index of specimens, fluorescence level was brighter. WHO grade had no correlation with fluorescence levels (χ² = 3.531, p = 0.171).

Conclusion

FLS-guided resection of MG is safe and effective. In the boundary area of MG, fluorescence levels and Ki-67 proliferation index showed correlation. FLS-guided resection achieved the function of “reducing tumor cell,” thus reducing the proliferation index in the lesion area.

The utilization of fluorescein in brain tumor surgery: a systematic review

INTRODUCTION

Sodium fluorescein (SF) is a green, water-soluble dye with the capacity to accumulate in cerebral areas as a result of damaged blood-brain barrier (BBB); this property allows SF to concentrate specifically at the tumor site of various types of brain neoplasms, making the tumor tissue more clearly visible.

EVIDENCE ACQUISITION

A literature search (1947-2018) was conducted with the keywords "fluorescein neurosurgery," "YELLOW neurosurgery," "fluorescein brain tumor," "YELLOW brain tumor." We included clinical studies, clinical trials, observational studies, only conducted on humans and concerning surgery; in addition, we have included 3 articles derived from the analysis of the references of other papers. Ultimately, 57 articles were included for further analysis.

EVIDENCE SYNTHESIS

Fluorescein as a fluorescent tracer in neuro-oncology is gaining a wider acceptance in the neurosurgical literature: until February 1st, 2018, at least 1099 neuro-oncological patients have been operated through fluorescein-assistance, mostly only after 2012. The most important application remains the aim to improve tumor visualization and extent of resection for high-grade gliomas (HGG), but the nonspecific mechanism of action is the theoretical base for its use also for tumors different from HGG. Nevertheless, no homogenous protocol of fluorescein utilization in neurosurgical oncology can be found in literature.

CONCLUSIONS

Fluorescein-guided surgery is a safe and effective technique to improve visualization and resection of different CNS tumors and conditions, based on BBB alteration, with a growing evidence-based background.