Fluorescein-assisted stereotactic needle biopsy of brain tumors: a single-center experience and systematic review

Sodium fluorescein and 5-aminolevulinic acid fluorescence- guided biopsy in brain lesions: a systematic review and meta-analysis

PURPOSE

Stereotactic brain biopsies are highly efficient for diagnosing intracerebral pathologies, particularly when surgical resection is infeasible. Fluorescence-based agents such as 5-aminolevulinic acid (5-ALA) and fluorescein sodium (NaFl) can enhance diagnostic accuracy and safety, improving the visualization of lesional tissues. This meta-analysis aimed to evaluate their effect on diagnostic yield and complication rates of brain biopsies.

METHODS

This study adhered to Cochrane and PRISMA guidelines. We assessed studies for diagnostic yield and complication rates. Data was analyzed using a random-effects model in RStudio. Diagnostic accuracy measures such as sensitivity and predictive values were calculated based on fluorescence visibility in biopsy samples.

RESULTS

Thirty-two non-randomized studies were included, comprising 947 patients, with a mean age ranging from 37 to 77 years, and a mean sample number ranging from 1 to 15 specimens. Diagnostic yields were high: 93% for NaFl and 96% for 5-ALA. Major complications occurred in 3% of procedures with both agents, while minor complications were reported in 7% and 5% with NaFl and 5-ALA respectively. The Negative-predictive-value (NPV) of 5-ALA and NaFl were 8-11% and 60-80% respectively. NaFl demonstrates higher sensitivity and specificity at 84% and 100% compared to 5-ALA's 66%. and 85% respectively.

CONCLUSION

5-ALA and NaFl provide high diagnostic yields with acceptable safety profiles in stereotactic biopsies. NaFl showed higher sensitivity and specificity. NaFl outperforms 5ALA in terms of NPV making it more efficient for small lesions near eloquent regions or major blood vessels. The significance of these findings can be further ascertained through randomized trials.

Efficacy, safety, and impact of fluorescein in frameless stereotactic needle biopsies - a case series

Stereotactic needle biopsy stands as a crucial method for diagnosing intracranial lesions unsuitable for surgical intervention. Nonetheless, the potential for sampling errors lead to innovative approaches to enhance diagnostic precision. This study contrasts the outcomes of patients undergoing fluorescein-assisted frameless stereotactic needle biopsy with those receiving traditional biopsies to evaluate the impact on diagnostic accuracy and safety. This study included patients with contrast-enhancing intracranial lesions, comprising a prospective group undergoing fluorescein-assisted biopsies and a retrospective group undergoing conventional biopsies at the same institution. We've collected data on demographics, procedural specifics, diagnostic outcomes, and postoperative events. A comparative analysis involved 43 patients who received fluorescein-assisted biopsies against 77 patients who underwent conventional biopsies. The average age was 60.5 years. The fluorescein group exhibited a 93% success rate in diagnosis, markedly higher than the 70.1% in the non-fluorescein group (OR = 5.67; 95%IC: 1.59-20.24; p < 0.01). The rate of complications was statistically similar across both cohorts. Despite its established value, stereotactic needle biopsy is susceptible to inaccuracies and complications. The application of fluorescence-based adjuncts like 5-ALA and fluorescein has been investigated to improve diagnostic fidelity and reduce risks. These technologies potentially minimize the necessity for multiple biopsies, decrease surgical duration, and provide immediate verification of tumor presence. Fluorescein-assisted stereotactic biopsy emerges as an effective, secure alternative to conventional methods.

Diagnostic Yield of Stereotactic Brain Biopsy in a Sub-Saharan Tertiary Center: A Comprehensive 10-Year Retrospective Analysis

BACKGROUND

Stereotactic brain biopsy is a crucial minimally invasive surgical technique leveraged to obtain tissue specimens from deep-seated intracranial lesions, offering a safer alternative to open craniotomy for patients who cannot tolerate the latter. Despite its effectiveness, the diagnostic yield varies across different centers and has not been widely studied in Sub-Saharan Africa.

METHODS

A single-center retrospective analysis was conducted on 67 consecutive stereotactic brain biopsy procedures carried out by experienced neurosurgeons between January 2012 and December 2022 at a tertiary center in Sub-Saharan Africa. Preoperative clinical status, biopsy type, postoperative complication rate, and histological diagnosis were meticulously analyzed. Factors associated with negative biopsy results were identified using IBM Statistical Package for the Social Sciences SPSS version for Mac, with Fisher exact test employed to detect differences in patient characteristics. Statistical significance was pegged at P < 0.05.

RESULTS

The overall diagnostic yield rate was 67%. Major contributors to negative biopsy outcomes were superficial location of the lesion, lesion size less than 10 cc, and the use of the Cape Town Stereotactic System. Enhanced yield rates of up to 93% were realized through the application of magnetic resonance imaging-based images, Stealth Station 7, and frozen section analysis. No correlation was observed between the number of cores obtained and the yield rate. Procedure complications were negligible, and no procedure-related mortality was recorded.

CONCLUSIONS

The diagnostic yield rate from our study was somewhat lower than previously reported in contemporary literature, primarily attributed to the differing definitions of diagnostic yield, the dominant use of the older framed Cape Town Stereotactic System, computed tomography-based imaging, and the absence of intraoperative frozen section. Nevertheless, biopsies conducted using the frameless system were comparable with studies from other global regions. Our findings reaffirm that stereotactic brain biopsy when complemented with magnetic resonance imaging-based imaging, frameless stereotactic systems and intraoperative frozen section is a safe, effective, and reliable method for obtaining histological diagnosis.

Fluorescence Assisted Stereotactic Biopsy of Contrast-Enhancing Brain Lesions: Can YELLOW 560-nm Filter Substitute Frozen Section?

BACKGROUND

The factors on which the accuracy of stereotactic brain biopsy depends are the competence of the neurosurgeon in obtaining a representative sample and the ability of the neuropathologist to make a histological diagnosis from a minuscule sample. Over the years intraoperative frozen section has enhanced the diagnostic yield of this minimally invasive procedure. Use of fluorescence in achieving a greater extent of resection is well-established in contemporary neurosurgical practice. This ability of brain tumors to take up the fluorescein sodium dye and glow under the YELLOW 560-nm filter has been utilized in a handful of studies to increase the diagnostic accuracy of stereotactic biopsy.

METHODS

We performed a prospective study where the fluorescein sodium dye was injected at a low dose and fluorescence of the biopsied core was compared with that of a tissue obtained from the normal parenchyma. Sample was labeled 'truly fluorescent' only when the glow was more than that of the tissue from normal parenchyma.

RESULTS

On cross-tabulating the index test (true fluorescence status) and the reference standard test (final histopathological report) the sensitivity of acquiring a representative sample was found to be 94.74%, specificity was 100%. The positive predictive value and negative predictive value were calculated to be 100% and 50% respectively. The diagnostic yield was comparable to that of the intraoperative frozen section.

CONCLUSION

The use of the YELLOW 560-nm filter can make stereotactic biopsy faster, safer, less cumbersome, and more cost-effective, and can be used as a substitute for the frozen section in resource-constrained centers.

Intraoperative Fluorescein Sodium in Pediatric Neurosurgery: A Preliminary Case Series from a Singapore Children’s Hospital

(1) Background: Fluorescein sodium (Na-Fl) has been described as a safe and useful neurosurgical adjunct in adult neurooncology. However, its use has yet to be fully established in children. We designed a study to investigate the use of intraoperative Na-Fl in pediatric brain tumor surgery. (2) Methods: This is a single-institution study for pediatric brain tumor patients managed by the Neurosurgical Service, KK Women’s and Children’s Hospital. Inclusion criteria consists of patients undergoing surgery for suspected brain tumors from 3 to 19 years old. A predefined intravenous dose of 2 mg/kg of 10% Na-Fl is administered per patient. Following craniotomy, surgery is performed under alternating white light and YELLOW-560 nm filter illumination. (3) Results: A total of 21 patients with suspected brain tumours were included. Median age was 12.1 years old. For three patients (14.3%), there was no significant Na-Fl fluorescence detected and their final histologies reported a cavernoma and two radiation-induced high grade gliomas. The remaining patients (85.7%) had adequate intraoperative fluorescence for their lesions. No adverse side effects were encountered with the use of Na-Fl. (4) Conclusions: Preliminary findings demonstrate the safe and efficacious use of intraoperative Na-Fl for brain tumors as a neurosurgical adjunct in our pediatric patients.

Use of fluorescein sodium-assisted intraoperative sample validation to maximize the diagnostic yield of stereotactic brain biopsy: progress toward a new standard of care?

OBJECTIVE

In patients with contraindication to open resection, histological diagnosis is obtained through a stereotactic biopsy (SB). Missed diagnoses and sampling errors are important limitations of SB; therefore, various ways have been proposed to increase the diagnostic yield (DY). Intraoperative histopathology can obtain a DY exceeding 98% but with several drawbacks, namely prolonged operative times and logistic concerns. The objective of this study was to evaluate whether intraoperative validation of samples with fluorescein sodium can obtain a high DY with the same ease of use as standard SB.

METHODS

One hundred three consecutive cases of frameless neuronavigated SB performed at the authors' center from May 2013 to June 2021 were included. Two groups were compared: 46 patients underwent standard nonassisted SB (nSB), and 57 patients underwent fluorescein sodium-assisted SB (fSB). Data were collected retrospectively before 2017 and prospectively thereafter. DY, operative time, and rate of complications were compared between the two groups. The surgical technique for fSB was standardized, and a novel classification system for intraoperative fluorescence findings was developed.

RESULTS

Statistically significant differences between the two groups were identified. The DY of the fSB group (100%, 95% CI 93.73%-100%) was significantly greater than that of the nSB group (89.13%, 95% CI 80.14%-98.13%) (p = 0.0157). No statistically significant differences were observed in terms of mean operative time (p = 0.7104), intraoperative complications (p = 0.999), or postoperative complications (p = 0.5083).

CONCLUSIONS

Compared with standard nSB, fSB showed a significantly higher DY and similar surgical time and rate of complications. The ease of use, wide diagnostic spectrum, and low cost make fluorescein sodium preferable to other fluorophores. The present study strengthens the limited data in the literature indicating routine use of fSB. The proposed workflow suggests that fSB should be the standard of care for contrast-enhanced cases. Intraoperative histopathology should be limited to nonenhancing cases, and nSB should be avoided. Future prospective multicenter studies will be useful for further validation of our findings.

Advances, technological innovations, and future prospects in stereotactic brain biopsies

Stereotactic brain biopsy is one of the most frequently performed brain surgeries. This review aimed to expose the latest cutting-edge and updated technologies and innovations available to neurosurgeons to safely perform stereotactic brain biopsy by minimizing the risks of complications and ensuring that the procedure is successful, leading to a histological diagnosis. We also examined methods for improving preoperative, intraoperative, and postoperative workflows. We performed a comprehensive state-of-the-art literature review. Intraoperative histology, fluorescence, and imaging techniques appear as smart tools to improve the diagnostic yield of biopsy. Constant innovations such as optical methods and augmented reality are also being made to increase patient safety. Robotics and integrated imaging techniques provide an enhanced intraoperative workflow. Patients' management algorithms based on early discharge after biopsy optimize the patient's personal experience and make the most efficient possible use of the available hospital resources. Many new trends are emerging, constantly improving patient care and safety, as well as surgical workflow. A parameter that must be considered is the cost-effectiveness of these devices and the possibility of using them on a daily basis. The decision to implement a new instrument in the surgical workflow should also be dependent on the number of procedures per year, the existing stereotactic equipment, and the experience of each center. Research on patients' postbiopsy management is another mandatory approach to enhance the safety profile of stereotactic brain biopsy and patient satisfaction, as well as to reduce healthcare costs.

Roles and outcomes of stereotactic biopsy for adult patients with brainstem lesion

PURPOSE

This study aimed to assess the benefit-risk ratio by determining diagnostic yield and safety of brainstem biopsies in adult patients. The secondary objectives were (i) to compare brainstem biopsy safety and postbiopsy patients' outcomes and survival with those of patients biopsied for a brain or cerebellar lesion, and (ii) to assess the impact of brainstem biopsy on final diagnosis and further therapeutic management.

METHODS

Among 1784 stereotactic biopsies performed in adult patients at a tertiary center between April 2009 and October 2020, we retrospectively examined 50 consecutive brainstem biopsies. We compared variables regarding diagnostic yield, safety and post-biopsy outcomes between brainstem biopsy patients and brain/cerebellum biopsy patients.

RESULTS

Brainstem biopsy led to a diagnosis in 86% of patients (94.6% in patients with suspected tumor). Lesion contrast enhancement on imaging was the sole predictor of obtaining a diagnosis. Rates of symptomatic complications and mortality were significantly higher in brainstem biopsy patients compared to brain/cerebellum biopsy patients (20% vs 0%; p < 0.001 and 6% vs 0%; p = 0.01, respectively). Transfrontal trajectory and prebiopsy swallowing disorders were predictors of brainstem biopsy-related symptomatic complications. Brainstem biopsy findings led to diagnostic change in 22% of patients.

CONCLUSIONS

Stereotactic biopsy in adult patients with brainstem lesion has a high diagnostic yield. Although stereotactic brainstem biopsy is associated with more functional and fatal complications than biopsies targeting the brain/cerebellum, its safety profile appears acceptable. Thus, the benefit-risk ratio of stereotactic biopsy in patients with brainstem lesion is favorable but should nevertheless be carefully weighted on a case-by-case basis.

Indicators of correct targeting in stereotactic biopsy of intracranial lesions

Background:

Confirmation of whether a stereotactic biopsy was performed in the correct site is usually dependent on the frozen section or on novel tumor-specific markers that are not widely available. Immediate postoperative computed tomography (CT) or magnetic resonance (MR) is routinely performed in our service after biopsy. In this retrospective study, we have carefully analyzed these images in an attempt to determine the presence of markers that indicate appropriate targeting.

Methods:

Medical records and neuroimages of patients who underwent stereotactic biopsy of intracranial lesions were reviewed. The following variables were assessed: age, sex, anatomopathology, lesion site, complications, diagnostic accuracy, and the presence of image markers.

Results:

Twenty-nine patients were included in this case series. About 96.6% of the biopsies were accurate according to the permanent section. Of the 86.2% of patients with intralesional pneumocephalus on the postoperative images, 51.7% additionally presented petechial hemorrhage. In 13.8% of the cases, no image markers were identified.

Conclusion:

This is the first report of intralesional pneumocephalus and petechial hemorrhage as indicators of appropriate targeting in stereotactic biopsy. In the majority of the cases, an immediate postoperative head CT, which is widely available, can estimate how adequate the targeting is. To use intralesional pneumocephalus/ petechial hemorrhages as not only postoperative but also as intraoperative markers of appropriate targeting, it is advised that the surgical wound should be temporarily closed and dressed after the biopsy so that the patient can undergo a CT/MR scan and be checked for the presence of theses markers before removing the stereotactic frame.

Correlation of Tumor Pathology with Fluorescein Uptake and MRI Contrast-Enhancement in Stereotactic Biopsies

The utilization of fluorescein-guided biopsies has recently been discussed to improve and expedite operative techniques in the detection of tumor-positive tissue, as well as to avoid making sampling errors. In this study, we aimed to report our experience with fluorescein-guided biopsies and elucidate distribution patterns in different histopathological diagnoses in order to develop strategies to increase the efficiency and accuracy of this technique. We report on 45 fluorescence-guided stereotactic biopsies in 44 patients (15 female, 29 male) at our institution from March 2016 to March 2021, including 25 frame-based stereotactic biopsies and 20 frameless image-guided biopsies using VarioGuide^®. A total number of 347 biopsy samples with a median of 8 samples (range: 4–18) per patient were evaluated for intraoperative fluorescein uptake and correlated to definitive histopathology. The median age at surgery was 63 years (range: 18–87). Of the acquired specimens, 63% were fluorescein positive. Final histopathology included glioblastoma (n = 16), B-cell non-Hodgkin lymphoma (n = 10), astrocytoma, IDH-mutant WHO grade III (n = 6), astrocytoma, IDH-mutant WHO grade II (n = 1), oligodendroglioma, IDH-mutant and 1p/19q-codeleted WHO grade II (n = 2), reactive CNS tissue/inflammation (n = 4), post-transplantation lymphoproliferative disorder (PTLD; n = 2), ependymoma (n = 1), infection (toxoplasmosis; n = 1), multiple sclerosis (n = 1), and metastasis (n = 1). The sensitivity for high-grade gliomas was 85%, and the specificity was 70%. For contrast-enhancing lesions, the specificity of fluorescein was 84%. The number needed to sample for contrast-enhancing lesions was three, and the overall number needed to sample for final histopathological diagnosis was five. Interestingly, in the astrocytoma, IDH-mutant WHO grade III group, 22/46 (48%) demonstrated fluorescein uptake despite no evidence for gadolinium uptake, and 73% of these were tumor-positive. In our patient series, fluorescein-guided stereotactic biopsy increases the likelihood of definitive neuropathological diagnosis, and the number needed to sample can be reduced by 50% in contrast-enhancing lesions.

Neurosurgical Approaches to Brain Tissue Harvesting for the Establishment of Cell Cultures in Neural Experimental Cell Models

In recent decades, cell biology has made rapid progress. Cell isolation and cultivation techniques, supported by modern laboratory procedures and experimental capabilities, provide a wide range of opportunities for in vitro research to study physiological and pathophysiological processes in health and disease. They can also be used very efficiently for the analysis of biomaterials. Before a new biomaterial is ready for implantation into tissues and widespread use in clinical practice, it must be extensively tested. Experimental cell models, which are a suitable testing ground and the first line of empirical exploration of new biomaterials, must contain suitable cells that form the basis of biomaterial testing. To isolate a stable and suitable cell culture, many steps are required. The first and one of the most important steps is the collection of donor tissue, usually during a surgical procedure. Thus, the collection is the foundation for the success of cell isolation. This article explains the sources and neurosurgical procedures for obtaining brain tissue samples for cell isolation techniques, which are essential for biomaterial testing procedures.

Clinical outcomes as a function of the number of samples taken during stereotactic needle biopsies: a meta-analysis

BACKGROUND

Stereotactic needle biopsy remains the cornerstone for tissue diagnosis for tumors located in regions of the brain that are difficult to access through open surgery.

OBJECTIVE

We perform a meta-analysis of the literature to examine the relation between number of samples taken during biopsy and diagnostic yield, morbidity and mortality.

METHODS

We identified 2416 patients from 28 cohorts in studies published in PubMed database that studied stereotactic needle biopsies for tumor indications. Meta-analysis by proportions and meta-regression analyses were performed.

RESULTS

On meta-analysis, the morbidity profile of the published needle biopsy studies clustered into three groups: studies that performed < 3 samples (n = 8), 3-6 samples (n = 13), and > 6 samples during biopsy (n = 7). Pooled estimates for biopsy related morbidity were 4.3%, 16.3%, and 17% for studies reporting < 3, 3-6, and > 6 biopsy samples, respectively. While these morbidity estimates significantly differed (p < 0.001), the diagnostic yields reported for studies performing < 3 biopsies, 3-6 samples, and > 6 samples were comparable. Pooled estimates of diagnostic yield for these three groups were 90.4%, 93.8%, and 88.1%, respectively. Mortality did not significantly differ between studies reporting differing number of samples taken during biopsy.

CONCLUSIONS

Our meta-analysis suggests that morbidity risk in needle biopsy is non-linearly associated with the number of samples taken. There was no association between the number of biopsies taken, and diagnostic yield or mortality.

Diagnostic yield of fluorescence-assisted frame-based stereotactic biopsies of intracerebral lesions in comparison with frozen-section analysis

PURPOSE

Stereotactic biopsies are routinely used to establish a histological diagnosis of unclear cerebral pathologies. Intraoperatively, frozen-section analysis often confirms diagnostic tissue but also exhibits methodological pitfalls. Intraoperative five-aminolevulinic acid (5-ALA)-fluorescence has been described not only in gliomas but also in other cerebral pathologies. In this study, we assessed the 5-ALA contribution to the intraoperative confirmation of diagnostic tissue in frame-based stereotactic biopsies of unclear intracerebral lesions in direct comparison with frozen-section analysis.

METHODS

Patients scheduled for stereotactic biopsies of unclear intracerebral pathologies received 5-ALA preoperatively. Obtained samples were intraoperatively analyzed for the presence of 5-ALA-fluorescence. One sample was used for frozen-section and a second one for permanent histopathological analysis. The diagnostic yield of frozen-section and intraoperative 5-ALA-fluorescence was calculated. The inclusion criteria for this retrospective analysis were unclear intracerebral lesions with inconclusive imaging findings and several differential diagnoses.

RESULTS

A total of 39 patients with 122 obtained specimens were included. The overall diagnostic yield was 92.3%. 5-ALA-positive samples were obtained in 74.3% (29/39) of patients and all these samples contained diagnostic tissue. 5-ALA-fluorescence confirmed diagnostic tissue with a sensitivity of 100%, a specificity of 27%, a positive predictive value (PPV) of 78%, and a negative predictive value (NPV) of 100%. A clear diagnosis could be predicted by frozen section with a sensitivity of 80%, a specificity of 100%, a PPV of 100%, and NPV of 30%; Fisher's exact test p = 0.01.

CONCLUSION

The 5-ALA-fluorescence in stereotactic biopsies of unclear intracerebral pathologies exhibits a high PPV/NPV for intraoperative confirmation of diagnostic tissue and might increase the diagnostic yield of the procedure by overcoming some of the limitations of frozen-section.

Reliability of fluorescein-assisted stereotactic brain biopsies in predicting conclusive tissue diagnosis

BACKGROUND

The purpose of this study was to assess the reliability of fluorescein sodium in predicting conclusive tissue diagnosis in stereotactic brain biopsies and to characterize features of contrast-enhancing and non-enhancing MRI lesions associated with fluorescence.

METHODS

A total of 19 patients were studied, 14 of which had contrast-enhancing and 5 of which had non-enhancing lesions on preoperative T1 post-gadolinium MRI scan. All patients received 3 mg/kg fluorescein sodium during anesthesia induction. Biopsy specimens were photographed under the operating microscope, using the Yellow560 module, prior to histopathological analysis. Two observers blinded to the MRI scans and histopathological results categorized the photographs retrospectively as "fluorescent" or "not fluorescent." Inter-rater agreement was assessed using Cohen's kappa coefficient. Sensitivity, specificity, and positive predictive value of fluorescence reliability were calculated for MRI contrast-enhancing lesions and confirmed location-concordance of tumor pathology based on rater's fluorescence status assessment. Results were correlated finally with final results on permanent sections.

RESULTS

Strength of inter-rater fluorescence status agreement was found to be "substantial" (kappa = 0.771). Sensitivity, specificity, and positive predictive value for "fluorescent" and "not fluorescent" specimen in comparison with MRI contrast-enhancing lesions were 97%, 40%, and 82%, respectively. Sensitivity, specificity, and positive predictive value for confirmed tumor pathology were 100%, 63%, and 91%, respectively. Permanent pathology revealed high-grade glioma n = 5, low-grade glioma n = 3, lymphoma n = 5, pineal tumor n = 2, hamartoma n = 1, and nonspecific hypercellularity n = 3.

CONCLUSIONS

Fluorescein-assisted stereotactic brain biopsies demonstrated a high likelihood to manifest fluorescence in contrast-enhancing MRI lesions, while adequately predicting conclusive tumor pathology.

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.

Use of 5-Aminolevulinic Acid for Confirmation of Lesional Biopsy Sample in Presumed High-Grade Glioma

BACKGROUND

5-amniolevulinic acid (5-ALA) assists neurosurgeons in defining operative margins during resection of high-grade gliomas, leading to improved rates of complete resection of enhancing tumor and progression-free survival. Here, we propose the use of 5-ALA in stereotactic biopsy for confirmation that the sample obtained is from the targeted mass. To the knowledge of the authors, this is the first known record of 5-ALA use for confirmation of pathologic specimen in stereotactic brain biopsy in the United States. This technique could be pivotal for lesions in highly eloquent areas where it is important to take as little tissue as possible in an effort to decrease neurologic deficits while still obtaining a diagnostic biopsy sample.

CASE DESCRIPTION

The patient is a 67-year-old male who initially presented with computed tomography and magnetic resonance imaging concerning for a high-grade glioma in the right basal ganglia and deep white matter of the frontal lobe. Final pathology concluded that specimens obtained during biopsy were indeed pathologic at the periphery of the lesion, and there was necrotic tissue at the center of the lesion. Fluorescence of biopsy samples was 100% concordant with pathologic analysis.

CONCLUSIONS

5-ALA may prove a useful tool for intraoperative confirmation of pathologic tissue, especially in areas of high eloquence, where small biopsy sizes are essential. It may also obviate the need for an intraoperative consultation to a pathologist. However, additional studies with larger study populations are warranted.

Neuroendoscopic Intraoperative Ultrasound-Guided Technique for Biopsy of Paraventricular Tumors

Different tumors can be encountered in the paraventricular regions, and whereas their deep location often make them difficult to access surgically, they may be amenable to chemotherapy and/or radiotherapy. Therefore, tumor biopsy and histologic diagnosis are mandatory to optimize treatment. Different technical procedures have been recommended; the neuroendoscopic approach is accepted and widely used, in particular with an enlarged ventricular system. However, specifically with paraventricular tumors, tissue sampling may be challenging. In such a scenario, the use of intraoperative ultrasonography technique can add some advantages regarding diagnostic accuracy and procedure safety. Accordingly, in this study we describe a novel technical procedure in 7 selected patients in whom tumor tissue biopsy was performed in a coupled neuroendoscopic and ultrasound-guided environment. We define a neuroendoscopic intraoperative ultrasound technique. The main advantages of this technique are the identification of the tumor that may not been clearly identified underneath the ventricular ependymal through the neuroendoscopic window alone, and furthermore, that this technique gives the possibility to detect the depth of the needle advance∖ment in the selected tissue while labeling the lesion beneath the ventricular ependyma. Moreover, intraoperative ultrasonography can reveal in a real-time fashion intracranial hemorrhages that may occur after tissue biopsy, therefore providing a useful tool to achieve valid and directed hemostasis when needed.

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.