5-aminolevulinic Acid Fluorescence Research Articles

Association of 5-aminolevulinic acid fluorescence guided resection with photodynamic therapy in recurrent glioblastoma: a matched cohort study.

Glioblastoma is a malignant and aggressive brain tumour that, although there have been improvements in the first line treatment, there is still no consensus regarding the best standard of care (SOC) upon its inevitable recurrence. There are novel adjuvant therapies that aim to improve local disease control. Nowadays, the association of intraoperative photodynamic therapy (PDT) immediately after a 5-aminolevulinic acid (5-ALA) fluorescence-guided resection (FGR) in malignant gliomas surgery has emerged as a potential and feasible strategy to increase the extent of safe resection and destroy residual tumour in the surgical cavity borders, respectively. To assess the survival rates and safety of the association of intraoperative PDT with 5-ALA FGR, in comparison with a 5-ALA FGR alone, in patients with recurrent glioblastoma. This article describes a matched-pair cohort study with two groups of patients submitted to 5-ALA FGR for recurrent glioblastoma. Group 1 was a prospective series of 11 consecutive cases submitted to 5-ALA FGR plus intraoperative PDT; group 2 was a historical series of 11 consecutive cases submitted to 5-ALA FGR alone. Age, sex, Karnofsky performance scale (KPS), 5-ALA post-resection status, T1-contrast-enhanced extent of resection (EOR), previous and post pathology, IDH (Isocitrate dehydrogenase), Ki67, previous and post treatment, brain magnetic resonance imaging (MRI) controls and surgical complications were documented. The Mantel-Cox test showed a significant difference between the survival rates (p = 0.008) of both groups. 4 postoperative complications occurred (36.6%) in each group. As of the last follow-up (January 2024), 7/11 patients in group 1, and 0/11 patients in group 2 were still alive. 6- and 12-months post-treatment, a survival proportion of 71,59% and 57,27% is expected in group 1, versus 45,45% and 9,09% in group 2, respectively. 6months post-treatment, a progression free survival (PFS) of 61,36% and 18,18% is expected in group 1 and group 2, respectively. The association of PDT immediately after 5-ALA FGR for recurrent malignant glioma seems to be associated with better survival without additional or severe morbidity. Despite the need for larger, randomized series, the proposed treatment is a feasible and safe addition to the reoperation.

Combination of Tractography, Intraoperative Computed Tomography and 5-Aminolevulinic Acid Fluorescence in Stereotactic Brain Biopsies: A Case Series.

Stereotactic needle biopsy (SNB) may be performed to collect tissue samples from lesions not amenable to open surgery. Integration of tractography, intraoperative imaging and fluorescence has been applied to reduce risk of complications and confirm the adequacy of bioptic specimens. Clinical and radiological data from patients who underwent stereotactic needle biopsy with the use of intraoperative CT, tractography and 5-aminolevulinic acid (5-ALA) fluorescence in a single Hospital were retrospectively reviewed to evaluate the accuracy and safety of the procedure. Seven patients were included in the study, and all the collected specimens showed red fluorescence. In six of them, the final histopathological diagnosis was grade 4 glioblastoma IDH-wt and in the other case it was Diffuse large B-Cell Lymphoma. The integration of tractography, intraoperative CT and 5-ALA as an intraoperative marker of diagnostic samples may be suggested in biopsies of suspect gliomas and lymphomas. The cost-effectiveness of the procedure should be evaluated in future studies.

Early-stage diagnosis of bladder cancer using surface-enhanced Raman spectroscopy combined with machine learning algorithms in a rat model

Early diagnosis and accurate assessment of tumor development facilitate early bladder cancer resection and initiation of drug therapy. This study enabled an early, accurate, label-free, noninvasive diagnosis of bladder tumors by analyzing nano-biomarkers in a single drop of urine through surface-enhanced Raman spectroscopy (SERS). In a standard N-butyl-N-4-hydroxybutyl nitrosamine–induced rat model of bladder cancer, cancer stage and polyp tumor development were monitored using a small endoscope with a diameter of 1.2 mm in a minimally invasive manner without the need to kill the rats. Samples were divided into cancer-free, early-stage, and polyp-form cancer. Training data were classified according to micro-cystoscopic 5-aminolevulinic acid fluorescence diagnosis, and specimens were postmortem verified through histopathological analysis. A drop of urine from each sample group was placed on an Au-coated zinc oxide nanoporous chip to filter nano-biomaterials and selectively enhance the Raman signals of nanoscale analytes via SERS. Principal component analysis was used to reduce the dimensionality of the collected Raman spectra, and partial least squares discriminant analysis was used to find diagnostic clusters based on the labeled samples. The combination of SERS and machine learning achieved an accuracy ≥99.6% in diagnosing both early- and polyp-stage bladder tumors. With an area under the receiver operating characteristic curve greater than 0.996, the accuracy of the diagnosis in the rat model suggests that SERS-based diagnostic methods are promising when coupled with machine learning. Low-cost, label-free, and noninvasive surface-enhanced Raman spectra are ideal for developing clinically relevant point-of-care diagnostic techniques.

Identification of CD44 as a Reliable Biomarker for Glioblastoma Invasion: Based on Magnetic Resonance Imaging and Spectroscopic Analysis of 5-Aminolevulinic Acid Fluorescence.

Recurrent glioblastoma multiforme (GBM) is largely attributed to peritumoral infiltration of tumor cells. As higher CD44 expression in the tumor periphery correlates with higher risk of GBM invasion, the present study analyzed the relationship between CD44 expression and magnetic resonance imaging (MRI)-based invasiveness of GBM on a large scale. We also quantitatively evaluated GBM invasion using 5-aminolevulinic acid (5-ALA) spectroscopy to investigate the relationship between CD44 expression and tumor invasiveness as evaluated by intraoperative 5-ALA intensity. Based on MRI, GBM was classified as high-invasive type in 28 patients and low-invasive type in 22 patients. High-invasive type expressed CD44 at a significantly higher level than low-invasive type and was associated with worse survival. To quantitatively analyze GBM invasiveness, the relationship between tumor density in the peritumoral area and the spectroscopic intensity of 5-ALA was investigated. Spectroscopy showed that the 5-ALA intensity of infiltrating tumor cells correlated with tumor density as represented by the Ki-67 staining index. No significant correlation between CD44 and degree of 5-ALA-based invasiveness of GBM was found, but invasiveness of GBM as evaluated by 5-ALA matched the classification from MRI in all except one case, indicating that CD44 expression at the GBM periphery could provide a reliable biomarker for invasiveness in GBM.

5-Aminolevulinic Acid Fluorescence-Guided Surgery in Head and Neck Squamous Cell Carcinoma.

To determine the utility of 5-aminolevulinic acid (5-ALA) fluorescence for resection of head and neck carcinoma. In this prospective pilot trial, 5-ALA was administered as an oral suspension 3-5 h prior to induction of anesthesia for resection of head and neck squamous cell carcinoma (HNSCC). Following resection, 405 nm blue light was applied, and fluorescence of the tumor as well as the surgical bed was recorded. Specimen fluorescence intensity was graded categorically as none (score = 0), mild (1), moderate (2), or robust (3) by the operating surgeon intraoperatively and corroborated with final pathologic diagnosis. Seven patients underwent resection with 5-ALA. Five (83%) were male with an age range of 33-82 years (mean = 60). Sites included nasal cavity (n = 3), oral cavity (n = 3), and the larynx (n = 1). All specimens demonstrated robust fluorescence when 5-ALA was administered 3-5 h preoperatively. 5-ALA fluorescence predicted the presence of perineural invasion, a positive margin, and metastatic lymphadenopathy. Two patients had acute photosensitivity reactions, and one patient had a temporary elevation of hepatic enzymes. 5-ALA induces robust intraoperative fluorescence of HNSCC, capable of demonstrating a positive margin, perineural invasion, and metastatic nodal disease. Although no conclusions are there about the safety of this drug in the head and neck cancer population, our study parallels the extensive safety data in the neurosurgical literature. Future applications may include intraoperative assessment of margin status, diagnostic accuracy, and impacts on survival. 4 Laryngoscope, 134:741-748, 2024.

Benefits of combined use of 68−Ga Dotatoc and 5-ALA fluorescence for recurrent atypical skull-base meningioma after previous microsurgery and Gamma Knife radiosurgery: a case report

BackgroundStudies of novel microsurgical adjuncts, such as 5-aminolevulinic acid (5-ALA) fluorescence have shown various fluorescence patterns within meningiomas, opening new avenues for complete microsurgical resection. Here, we present a recurrent, radiation-induced meningioma, previously operated on two occasions (initial gross total resection and subtotal 12 years later) and also irradiated by Gamma Knife radiosurgery (GKR, 6 years after the first surgery). We thought to assess the usefulness of 68−Ga Dotatoc in surgical target planning and of 5-ALA as an adjunct for maximal microsurgical excision.Case reportWe report on a 43 years-old Caucasian male diagnosed with atypical, radiation induced WHO II meningioma, with left basal temporal bone implantation. Hodgkin lymphoma treated with cranial and mediastinal radiation during infancy marked his personal history. He underwent a first gross total microsurgical resection, followed 6 and 12 years later by Gamma Knife radiosurgery (GKR) and second subtotal microsurgical resection, respectively. Magnetic resonance imaging (MRI) displayed new recurrence 13 years after initial diagnosis. He was clinically asymptomatic but routine Magnetic resonance imaging showed constant progression. There was strong 68−Ga Dotatoc uptake. We used 5-ALA guided microsurgical resection. Intraoperative views confirmed strong fluorescence, in concordance with both preoperative Magnetic resonance imaging enhancement and 68−Ga Dotatoc. The tumor was completely removed, with meningeal and bone resection.ConclusionThe authors conclude that fluorescence-guided resection using 5-ALA is useful for recurrent atypical, radiation-induced meningioma even despite previous irradiation and multiple recurrences.

Histologic Definition of Enhancing Core and FLAIR Hyperintensity Region of Glioblastoma, IDH-Wild Type: A Clinico-Pathologic Study on a Single-Institution Series

The extent of resection beyond the enhancing core (EC) in glioblastoma IDH-wild type (GBM, IDHwt) is one of the most debated topics in neuro-oncology. Indeed, it has been demonstrated that local disease recurrence often arises in peritumoral areas and that radiologically-defined FLAIR hyperintensity areas of GBM IDHwt are often visible beyond the conventional EC. Therefore, the need to extend the surgical resection also to the FLAIR hyperintensity areas is a matter of debate. Since little is known about the histological composition of FLAIR hyperintensity regions, in this study we aimed to provide a comprehensive description of the histological features of EC and FLAIR hyperintensity regions sampled intraoperatively using neuronavigation and 5-aminolevulinic acid (5-ALA) fluorescence, in 33 patients with GBM, IDHwt. Assessing a total 109 histological samples, we found that FLAIR areas consisted in: (i) fragments of white matter focally to diffusely infiltrated by tumor cells in 76% of cases; (ii) a mixture of white matter with reactive astrogliosis and grey matter with perineuronal satellitosis in 15% and (iii) tumor tissue in 9%. A deeper knowledge of the histology of FLAIR hyperintensity areas in GBM, IDH-wt may serve to better guide neurosurgeons on the choice of the most appropriate surgical approach in patients with this neoplasm.

Endoscope-assisted visualization of 5-aminolevulinic acid fluorescence in surgery for brain metastases.

Fluorescence-guided resection of cerebral metastases has been proposed as an approach to visualize residual tumor tissue and maximize the extent of resection. Critics have argued that tumor cells at the resection margins might be overlooked under microscopic visualization because of technical limitations. Therefore, an endoscope, which is capable of inducing fluorescence, has been applied with the aim of improving exposure of fluorescent tumor tissue. In this retrospective analysis, authors assessed the utility of endoscope assistance in 5-aminolevulinic acid (5-ALA) fluorescence-guided resection of brain metastases. Between June 2013 and December 2016, a standard 20-mg/kg dose of 5-ALA was administered 4 hours prior to surgery in 26 patients with suspected single brain metastases. After standard neuronavigated microsurgical tumor resection, a microscope capable of inducing fluorescence was used to examine tumor margins. The authors classified the remaining fluorescence into 3 grades (0 = none, 1 = weak, and 2 = strong). Endoscopic assistance was employed if no or only weak fluorescence was visualized at the resection margins under the microscope. Endoscopically identified fluorescent tissue at the margins was resected and evaluated separately via histological examination to prove or disprove tumor infiltration. Under the microscope, weakly fluorescent tissue was seen at the margins of the resection cavity in 15/26 (57.7%) patients. In contrast, endoscopic inspection revealed strongly fluorescent tissue in 22/26 (84.6%) metastases. In 11/26 (42.3%) metastases no fluorescence at the tumor margins was detected by the microscope; however, strong fluorescence was visualized under the endoscope in 7 (63.6%) of these 11 metastases. In the 15 metastases with microscopically weak fluorescence, strong fluorescence was seen when using the endoscope. Neither microscopic nor endoscopic fluorescence was found in 4/26 (15.4%) cases. In the 26 patients, 96 histological specimens were obtained from the margins of the resection cavity. Findings from these specimens were in conjunction with the histopathological findings, allowing identification of metastatic infiltration with a sensitivity of 95.5% and a specificity of 75% using endoscope assistance. Fluorescence-guided endoscope assistance may overcome the technical limitations of the conventional microscopic exposure of 5-ALA-fluorescent metastases and thereby increase visualization of fluorescent tumor tissue at the margins of the resection cavity with high sensitivity and acceptable specificity.

EMERGING ROLE OF URINARY BIOMARKERS IN DETECTION OF UROTHELIAL BLADDER CARCINOMA IN SOUTH INDIAN POPULATION

Urine cytology is used for screening of exfoliated bladder cells from voided urine but lacks sensitivity. This study aims to check the efficacy of 5-aminolevulinic acid (5- ALA) fluorescence cytology and establish a high sensitivity approach in detecting flat, in-situ and/or small lesions that are hardly visible under conventional cystoscopy. Intracellular PPIX allows red fluorescence detection. In this study, 5-ALA fluorescent cytology using urine was compared with conventional cytology in the diagnosis of bladder tumors. In this prospective study, we compared the sensitivity and specificity between conventional cytology, 5-ALA fluorescent cytology and FDA approved commercially available kits (NMP-22 and BTA). The percentage of Protoporphyrin IX facilitated by 5-ALA was amplified in cancer urothelial cells compared to normal urothelial cells. The sensitivity of conventional cytology and 5-ALA fluorescent cytology was 64% and 96% respectively, whereas the specificity was 92% and 98.67% respectively. In conclusion, 5-ALA induced fluorescent urine cytology demonstrated promising outcomes in the detection of bladder carcinoma cells. Furthermore, low grade and low stage tumor cells as well as flat lesions were also positively and accurately interpreted using 5-ALA fluorescent cytology.

5-Aminolevulinic acid fluorescence in brain non-neoplastic lesions: a systematic review and case series.

Fluorescence-guided surgery with 5-aminolevulinic acid (5-ALA) is used to assist brain tumor resection, especially for high-grade gliomas but also for low-grade gliomas, metastasis, and meningiomas. With the increasing use of this technique, even to assist biopsies, high-grade glioma-mimicking lesions had misled diagnosis by showing 5-ALA fluorescence in non-neoplastic lesions such as radiation necrosis and inflammatory or infectious disease. Since only isolated reports have been published, we systematically review papers reporting non-neoplastic lesion cases with 5-ALA according with the PRISMA guidelines, present our series, and discuss its pathophysiology. In total, 245 articles were identified and 12 were extracted according to our inclusion criteria. Analyzing 27 patients, high-grade glioma was postulated as preoperative diagnosis in 48% of the cases. Microsurgical resection was performed in 19 cases (70%), while 8 patients were submitted to biopsy (30%). We found 4 positive cases in demyelinating disease (50%), 4 in brain abscess (80%), 1 in neurocysticercosis (33%), 1 in neurotoxoplasmosis, infarction, and hematoma (100%), 4 in inflammatory disease (80%), and 3 in cortical dysplasia (100%). New indications are being considered especially in benign lesion biopsies with assistance of 5-ALA. Using fluorescence as an aid in biopsies may improve procedure time, number of samples, and necessity of intraoperative pathology. Further studies should include this technology to encourage more beneficial uses.

Experiences with a 3D4K Digital Exoscope System (ORBEYE) in a Wide Range of Neurosurgical Procedures.

Exoscopic 3D4K video systems (EX) have recently been introduced as an alternative to conventional operating microscopes (OM). However, experience in handling and setup remains scarce. This study evaluated the practicability of exoscopic surgery in a wide range of procedures. All EX operations performed between August 2018 and May 2020 were evaluated and compared with procedures using OM. A standardized questionnaire was used to evaluate surgeons' comfort, image quality (including fluorescence modes), and handling. In all, 513 EX operations were performed during the investigated period. EX was generally rated as a valuable surgical tool. In particular, the digital 5-aminolevulinic acid (5-ALA) fluorescence and the comfort level of posture during surgery were stated to be superior to OM (100 and 83%, respectively). EX has been used for a significant number of neurosurgical procedures. While presuming that the technical methodology as such will not influence outcome of glioma surgery, proof of equipoise between different techniques expands the spectrum of surgical environments giving neurosurgeons a choice to work according to their preferred ergonomics.

Does pigmentation, hemosiderin and blood effect visible 5-ALA fluorescence in cerebral melanoma metastasis?

IntroductionThe clinical impact of 5-aminolevulinic acid (5-ALA) fluorescence during resection of brain metastases is not yet clear.. Recent data demonstrated significantly lower incidence of visible fluorescence in cerebral melanoma metastases (CMM) compared to other brain metastases (BM). The aim of this study was to investigate if characteristic melanoma features such as pigmentation, intratumoural hemosiderin and bleeding have an influence on visible fluorescence in CMM. Materials and methodsA retrospective study of two neurosurgical centers was performed including adult patients with resection of CMM after preoperative administration of 5-ALA. Data on the fluorescence status (visible or no fluorescence), the fluorescence quality (strong, vague, none) and fluorescence homogeneity (homogeneous or heterogeneous) of each CMM were collected. The amount of melanin, hemosiderin and intratumoural bleeding was semi-quantitatively determined and automated computer-based calculation of the relative pigmented area was performed in fluorescing and non-fluorescing CMM samples. ResultsAltogether, 29 CMM were surgically removed after 5-ALA administration. Visible fluorescence was detected in 8 CMM (28%), whereas no fluorescence was detected in 21 CMM (72%). In detail, 3 tumors (10%) showed strong fluorescence, 5 tumors (17%) revealed vague fluorescence and in 21 tumors (72%) no fluorescence was found. In total, 8 fluorescing and 25 non-fluorescing CMM samples were investigated. According to the semi-quantitatively calculated fluorescence status, no statistically significant difference in the median amount of melanin (p = 0.242), hemosiderin (p = 0.603) and bleeding (p = 0.762) between CMM samples with and without visible fluorescence was found. Moreover, the automatically assessed relative pigmented area did not show a statistically significant difference between samples with visible and no fluorescence (p = 0.966). ConclusionOur data indicate that 5-ALA fluorescence is not dependent on the amount of pigmentation, intratumoural hemosiderin and bleeding in CMM. We thus assume that other factors are responsible for the low rate of visible fluorescence in CMM.

Immunoregulatory effects of glioma-associated stem cells on the glioblastoma peritumoral microenvironment: a differential PD-L1 expression from core to periphery?

Glioma-associated stem cells (GASCs) have been indicated as possible players in supporting growth and recurrence in glioblastoma. However, their role in modulating immune response in the peritumoral area has not yet been described. In this study, the authors aimed to investigate programmed death-ligand 1 (PD-L1) differential expression at the protein level in GASCs derived from different tumor areas (core, periphery, and surrounding healthy brain). Tumor tissue samples were collected from patients who underwent surgery for a histopathologically confirmed diagnosis of glioblastoma. Sampling sites were confirmed via neuronavigation and categorized on 5-aminolevulinic acid (5-ALA) fluorescence as bright (ALA+), pale (ALA PALE), or negative (ALA-), which corresponds to the tumor mass, infiltrated peritumoral area, and healthy brain, respectively, during surgery. GASCs were first isolated from the 3 regions and analyzed; then Western blot analysis was used to evaluate the level of PD-L1 expression in the GASCs. Overall, 7 patients were included in the study. For all patients, the mean values ± SD of PD-L1 expression in GASCs for ALA+, ALA PALE, and ALA- were 1.12 ± 1.14, 0.89 ± 0.63, and 0.57 ± 0.18, respectively. The differentially expressed values of PD-L1 in GASCs sampled from the 3 areas were found to be significant (p < 0.05) for 3 of the 7 patients: patient S470 (ALA+ vs ALA- and ALA PALE vs ALA-), patient S473 (ALA+ vs ALA PALE and ALA PALE vs ALA-), and patient S509 (ALA+ vs ALA-). This analysis showed, for the first time, that GASCs expressed a constitutive level of PD-L1 and that PD-L1 expression in GASCs was not uniform among patients or within the same patient. GASC analysis combined with 5-ALA-guided sampling (from core to periphery) made it possible to highlight the role of the tumor microenvironment at the infiltrating margin, which might cause clinical resistance, opening interesting perspectives for the future.

TH21. CEREBROSPINAL FLUID PROTEOMICS TARGETED FOR CENTRAL NERVOUS SYSTEM PROCESSES IN BIPOLAR DISORDER

Primary central nervous system lymphoma (PCNSL) is a rare tumor with a poor prognosis. Early brain biopsy is essential to avoid a diagnostic delay. To date, reports of successful diagnosis for PCNSL of the corpus callosum by endoscopic biopsy are rare.Herein, we report the case of an elderly woman with PCNSL of the corpus callosum who initially presented with rapidly progressive dementia. The condition was finally diagnosed by microscopic biopsy after unsuccessful endoscopic biopsy. Moreover, the postoperative course was uneventful. She is currently receiving systemic chemotherapy.Early diagnosis and subsequent systemic chemotherapy with or without whole brain radiotherapy are critical for PCNSL. Endoscopic biopsy may be a diagnostic option for suspected PCNSL, although stereotactic needle biopsy is most commonly used.Utilizing neuronavigation and 5-aminolevulinic acid (ALA) fluorescence guidance could be helpful in identifying lesions insufficiently exposed by endoscopic visualization. However, cerebrospinal fluid (CSF) loss due to the endoscopic approach through the ventricle might be a cause of neuronavigation misregistration.

5-ALA Fluorescence Is a Powerful Prognostic Marker during Surgery of Low-Grade Gliomas (WHO Grade II)-Experience at Two Specialized Centers.

Simple Summary5-aminolevulinic acid (5-ALA) is administered orally before brain tumor surgery to improve intraoperative visualization of tumor tissue. In comparison to most of the aggressive high-grade gliomas, only a few low-grade gliomas (LGG) demonstrate visible fluorescence during surgery. As the prognosis of these LGG is hard to predict, we aimed to investigate if visible fluorescence might be an intraoperative marker for aggressive tumor behavior in patients with LGG. According to our data, we could demonstrate that intraoperative visible fluorescence is a predictor for early tumor progression, transformation into more aggressive higher-grade tumors, and shorter survival in LGG patients. Therefore, visible 5-ALA fluorescence is an intraoperative marker of unfavorable prognosis during surgery of LGG.The prediction of the individual prognosis of low-grade glioma (LGG) patients is limited in routine clinical practice. Nowadays, 5-aminolevulinic acid (5-ALA) fluorescence is primarily applied for improved intraoperative visualization of high-grade gliomas. However, visible fluorescence is also observed in rare cases despite LGG histopathology and might be an indicator for aggressive tumor behavior. The aim of this study was thus to investigate the value of intraoperative 5-ALA fluorescence for prognosis in LGG patients. We performed a retrospective analysis of patients with newly diagnosed histopathologically confirmed LGG and preoperative 5-ALA administration at two independent specialized centers. In this cohort, we correlated the visible intraoperative fluorescence status with progression-free survival (PFS), malignant transformation-free survival (MTFS) and overall survival (OS). Altogether, visible fluorescence was detected in 7 (12%) of 59 included patients in focal intratumoral areas. At a mean follow-up time of 5.3 ± 2.9 years, patients with fluorescing LGG had significantly shorter PFS (2.3 ± 0.7 vs. 5.0 ± 0.4 years; p = 0.01), MTFS (3.9 ± 0.7 vs. 8.0 ± 0.6 years; p = 0.03), and OS (5.4 ± 1.0 vs. 10.3 ± 0.5 years; p = 0.01) than non-fluorescing tumors. Our data indicate that visible 5-ALA fluorescence during surgery of pure LGG might be an already intraoperatively available marker of unfavorable patient outcome and thus close imaging follow-up might be considered.

Comparison of colour difference formulas to best distinguish resected areas of malignant brain tumours from their background using 5-aminolevulinic acid fluorescence.

Fluorescence-guided surgery (FGS) with 5-aminolevulinic acid (5-ALA) has been proven to assist neurosurgeons to achieve a more complete brain tumour resection. However, 5-ALA-guided surgery is limited since it is often difficult to distinguish the colour difference between the resected areas of malignant brain tumours from their background. Our aim was to evaluate which colour difference formula was optimal to distinguish between malignant brain tumours and the background healthy tissue using 5-ALA fluorescence. Thirty-seven patients with a primary or secondary malignant brain tumour ingested 5-ALA before the surgery. A 400 nm light was used to excite the fluorescence. Surgical videos were recorded for all the patients and a total of 183 samples were obtained from the fluorescent areas and their respective backgrounds. Three colour differences formulas - contrast ratio (CR), CIELab (ΔE*) and CIEDE2000 - were applied to the videos and compared using hot-cold maps. Baseline demographics, the tumour's location, the tumour's side, and tumour's World Health Organization (WHO) grade was also analysed for correlations relating to the fluorescence. Chi-square and the Student's t-test were used for univariate relations. The three channels of the CIELAB colour space (L*, a* and b*) were analysed together and separately (since L* of fluorescent areas was significantly higher than the background). ΔE* resulted in good discrimination of a* and b*, and moderate but acceptable discrimination of L*. CIEDE2000 distinguished differences in a* and b*, although not in L*. The CR distinguished only L*, whereas the probability of discriminating a* and b* channels failed. Neither age, sex, tumour location, tumour size nor the WHO grade influenced the a*, b* and L* colour values (p > 0.05). Colour differences measured by ΔE* and CIEDE2000 correlated together (r = 0.99, p < 0.01), whereas CR correlated only with ΔE* (r = 0.21, p = 0.01) but not with CIEDE2000 (r = 0.07, p = 0.32). ΔE* obtained the best colour discrimination between the resected areas of malignant brain tumours and the background when compared to CR and CIEDE2000. Therefore, ΔE* may be the best formula to help neurosurgeons distinguish the colour differences when operating malignant brain tumours with 5-ALA fluorescence.

Improving the Usability of 5-Aminolevulinic Acid Fluorescence-Guided Surgery by Adding an Optimized Secondary Light Source

Tumors that take up and metabolize 5-aminolevulinic acid emit bright pink fluorescence when illuminated with blue light, aiding surgeons in identifying the margin of resection. The adoption of this method is hindered by the blue light illumination, which is too dim to safely operate under and therefore necessitates switching back and forth from white-light mode. The aim of this study was to examine the addition of an optimized secondary illuminant adapter to improve usability of blue-light mode without degrading tumor contrast. Color science methods were used to evaluate the color of the secondary illuminant and its impact on color rendering index as well as the tumor-to-background color contrast in data collected from 7 patients with high-grade gliomas (World Health Organization grade III and IV). A secondary illuminant adapter was built to provide 475-600 nm light the intensity of which can be controlled by the surgeon and was evaluated in 2 additional patients. Secondary illuminant color had opposing effects on color rendering index and tumor-to-background color contrast; providing surgeon control of intensity allows this trade-off to be balanced in real time. Demonstration in 2 high-grade glioma cases confirms this, showing that additional visibility adds value when intensity can be controlled by the surgeon. Addition of a secondary illuminant may mitigate surgeon complaints that the operative field is too dark under the blue light illumination required for 5-aminolevulinic acid fluorescence guidance by providing improved color rendering index without completely sacrificing tumor-to-background color contrast.

A Prospective Validation Study of the First 3D Digital Exoscope for Visualization of 5-ALA–Induced Fluorescence in High-Grade Gliomas

We report on the first use of a digital 3-dimensional (3D) exoscope equipped with a 5-aminolevulinic acid (5-ALA) fluorescence visual system. We conducted a prospective clinical trial to evaluate the utility and sensitivity/specificity of the Olympus Orbeye 3D digital exoscope when used to visualize 5-ALA-induced fluorescence in patients with high-grade glioma undergoing a clinically indicated craniotomy. At least 2 tissue samples were each obtained from regions of strong, weak. and no fluorescence and evaluated in a blinded manner by a neuropathologist. Twenty patients were enrolled. Intraoperative fluorescence was observed in 100% of subjects. One hundred twenty-one surgical specimens were collected for histopathological analysis; 40 with strong, 40 weak, and 41 with no visible fluorescence. Histopathology demonstrated 62.8% of samples (n= 76) contained abundant, 20.7% (n= 25) scarce, and 16.5% (n= 20) no tumor cells. Thirty-three of the 40 specimens (82.5%) in the strong fluorescence group correlated with abundant tumor cells and 7 (17.5%) with scarce. Twenty-nine of the 40 specimens (72.5%) in the weak fluorescence group correlated with abundant tumor cells, 7 (17.5%) with scarce, and 4 (10%) with none. Fourteen of the 41 (34.2%) specimens in the no fluorescence group had abundant tumor cells, 11 (26.8%) had scarce, and 16 (39%) had none. The sensitivity was 75% and specificity was 80%. The positive predictive value was 95% and negative predictive value was 39%. Visualization of 5-ALA-induced tumor fluorescence with use of the Orbeye 3D digital exoscope was feasible and associated with a high positive predictive value.

Prognostic Value of 5-ALA Fluorescence, Tumor Cell Infiltration and Angiogenesis in the Peritumoral Brain Tissue of Brain Metastases.

Simple SummaryIn a recent study, we observed 5-ALA fluorescence not only in brain metastases (BM) but also in the peritumoral brain tissue. However, the histopathological correlate of visible 5-ALA fluorescence in the peritumoral brain tissue is not fully understood. Therefore, we safely collected and analyzed tissue samples from fluorescing and non-fluorescing peritumoral brain tissue. Surprisingly, 5-ALA fluorescence in the peritumoral brain tissue did not correlate with tumor cell infiltration but did show a significant relation with angiogenesis. Moreover, the presence of angiogenesis significantly correlated with shorter time to local progression/recurrence and one-year survival. Consequently, angiogenesis in the peritumoral brain tissue might be a novel prognostic marker in BM. This represents the first study in the literature describing the prognostic impact of angiogenesis in fluorescent peritumoral brain tissue of BM, which might support individualized perioperative treatment concepts in the future.Complete resection is an indispensable treatment option in the management of brain metastases (BM). 5-aminolevulinic acid (5-ALA) fluorescence is used for improved intraoperative visualization of tumor tissue in gliomas and was recently observed in BM. We investigated the potential of 5-ALA fluorescence to visualize the infiltrative growth of BM in the peritumoral brain tissue and its histopathological correlate. Patients with BM resection after 5-ALA administration and collection of tissue samples from peritumoral brain tissue were included. Each tissue sample was histopathologically investigated for tumor cell infiltration and angiogenesis. Altogether, 88 samples were collected from the peritumoral brain tissue in 58 BM of 55 patients. Visible 5-ALA fluorescence was found in 61 (69%) of the samples, tumor infiltration in 19 (22%) and angiogenesis in 13 (15%) of samples. Angiogenesis showed a significant correlation with presence of fluorescence (p = 0.008). Moreover, angiogenesis was related to visible 5-ALA fluorescence and showed an association with patient prognosis since it was significantly correlated to shorter time to local progression/recurrence (p = 0.001) and lower one-year survival (p = 0.031). Consequently, angiogenesis in the peritumoral brain tissue of BM might be a novel prognostic marker for individualized perioperative treatment concepts in the future.

FLAIRectomy in Supramarginal Resection of Glioblastoma Correlates With Clinical Outcome and Survival Analysis: A Prospective, Single Institution, Case Series.

Extent of tumor resection (EOTR) in glioblastoma surgery plays an important role in improving survival. To analyze the efficacy, safety and reliability of fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) images used to guide glioblastoma resection (FLAIRectomy) and to volumetrically measure postoperative EOTR, which was correlated with clinical outcome and survival. A total of 68 glioblastoma patients (29 males, mean age 65.8) were prospectively enrolled. Hyperintense areas on FLAIR images, surrounding gadolinium-enhancing tissue on T1-weighted MR images, were screened for signal changes suggesting tumor infiltration and evaluated for supramaximal resection. The surgical protocol included 5-aminolevulinic acid (5-ALA) fluorescence, neuromonitoring, and intraoperative imaging tools. 5-ALA fluorescence intensity was analyzed and matched with the different sites on navigated MR, both on postcontrast T1-weighted and FLAIR images. Volumetric evaluation of EOTR on T1-weighted and FLAIR sequences was compared. FLAIR MR volumetric evaluation documented larger tumor volume than that assessed on contrast-enhancing T1 MR (72.6 vs 54.9 cc); residual tumor was seen in 43 patients; postcontrast T1 MR volumetric analysis showed complete resection in 64 cases. O6-methylguanine-DNA methyltransferase promoter was methylated in 8/68 (11.7%) cases; wild type Isocytrate Dehydrogenase-1 (IDH-1) was found in 66/68 patients. Progression free survival and overall survival (PFS and OS) were 17.43 and 25.11 mo, respectively. Multiple regression analysis showed a significant correlation between EOTR based on FLAIR, PFS (R2=0.46), and OS (R2=0.68). EOTR based on FLAIR and 5-ALA fluorescence is feasible. Safety of resection relies on the use of neuromonitoring and intraoperative multimodal imaging tools. FLAIR-based EOTR appears to be a stronger survival predictor compared to gadolinium-enhancing, T1-based resection.