Ex Vivo Fluorescein-Assisted Confocal Laser Endomicroscopy (CONVIVO® System) in Patients With Glioblastoma: Results From a Prospective Study

Abstract

BackgroundConfocal laser endomicroscopy (CLE) allowing intraoperative near real-time high-resolution cellular visualization is a promising method in neurosurgery. We prospectively tested the accuracy of a new-designed miniatured CLE (CONVIVO® system) in giving an intraoperative first-diagnosis during glioblastoma removal.MethodsBetween January and May 2018, 15 patients with newly diagnosed glioblastoma underwent fluorescein-guided surgery. Two biopsies from both tumor central core and margins were harvested, dividing each sample into two specimens. Biopsies were firstly intraoperatively ex vivo analyzed by CLE, subsequently processed for frozen and permanent fixation, respectively. Then, a blind comparison was conducted between CLE and standard permanent section analyses, checking for CLE ability to provide diagnosis and categorize morphological patterns intraoperatively.ResultsBlindly comparing CONVIVO® and frozen sections images we obtained a high rate of concordance in both providing a correct diagnosis and categorizing patterns at tumor central core (80 and 93.3%, respectively) and at tumor margins (80% for both objectives). Comparing CONVIVO® and permanent sections, concordance resulted similar at central core (total/partial concordance in 80 and 86.7% for diagnosis and morphological categorization, respectively) and lower at tumor margins (66.6% for both categories). Time from fluorescein injection and time from biopsy sampling to CONVIVO® scanning was 134 ± 31 min (122–214 min) and 9.23 min (1–17min), respectively. Mean time needed for CONVIVO® images interpretation was 5.74 min (1–7 min).ConclusionsThe high rate of diagnostic/morphological consistency found between CONVIVO® and frozen section analyses suggests the possibility to use CLE as a complementary tool for intraoperative diagnosis of ex vivo tissue specimens during glioblastoma surgery.

Rationale and Clinical Implications of Fluorescein-Guided Supramarginal Resection in Newly Diagnosed High-Grade Glioma

“…Alternatively, fluorescein could be combined with Raman spectroscopy, which has been shown to accurately delineate tumor versus normal brain at the margins of resection, with superior performance compared to 5-ALA (55). Confocal laser endomicroscopy has also been combined with fluorescein and recently investigated as a means of increasing extent of resection by providing real-time intraoperative verification of pathologic tumor tissue (56)(57)(58). Several studies have also mentioned the potential benefit of quantitatively measuring fluorescence intensity and integrating this technology with the operative microscope, which could increase both the safety and the sensitivity of fluorescein as an adjunct for glioma resection (9,17,29).…”

Confocal Laser Microscopy in Neurosurgery: State of the Art of Actual Clinical Applications

“…The last available work to date concerning ex vivo imaging in brain tumors surgery was the work of our group in 2020. We prospectively studied ex vivo the ability of Convivo to confer an intraoperative first-diagnosis during GBM removal, by blindly comparing intraoperative CLE and frozen/permanent sections results at both central core and tumor margins of tumors [ 42 ]. We were interested in both identifying the ability of such system in offering an intraoperative diagnosis, along with the ability to categorize morphological patterns, such as cellularity, vascularization and necrosis.…”

“…In this context, the work of Belykh in 2020 should be considered as a miliary stone, due to the extremely rigorous blinded study in analyzing CLE images from both neuropathologist and experienced/unexperienced neurosurgeons’ points of view and the huge amount of tumors investigated [ 41 ]. Looking at our work, in 2020 we reported the results of a rigorous blinded and prospective study where an optimal diagnostic concordance was obtained at the central core of 15 HGGs analyzed [ 42 ]. Even though one of the major limits of this study was the fact that just one hystotipe of tumor was analyzed, hence rendering it unsuitable to study the differential diagnosis ability of Convivo (programmed for the next in vivo study), we reported an optimal concordance among CLE imaging and histopathological/frozen section analysis at the central core of the different cases, with a rigorous blinded design.…”

“…In addition, considering ex vivo studies, a very paucity of data regarding biopsies taken at tumor margins is present. As anticipated, our work in 2020 was the first prospective and blinded ex vivo study to specifically check for ability of Convivo system to identify tumor tissue at borders in HGGs [ 42 ]. Comparing Convivo and frozen section analyses, we obtained a high rate of concordance at tumor borders in both obtaining a diagnosis and categorizing morphological patterns.…”

Optical Characterization of Sodium Fluorescein In Vitro and Ex Vivo

“…The implications of the observed changes in optical properties are of relevant nature, especially if these fluorescent-based assays are used for further diagnostic purposes. Furthermore, in the clinical setting, the utilization of NaFl in combination with in-depth in vivo and ex vivo imaging techniques such as confocal laser endomicroscopy has also been discussed in recent studies in aiding histopathological diagnoses ( 25 , 26 ). Hence, the increasing role of NaFl in such settings poses increasing interest on NaFl tumor kinetics, and further analysis of its spectroscopic features may help to distinguish its free form from fluorescein metabolites (fluorescein glucuronide).…”