Single Institution Prospective Feasibility Analysis of in vivo Confocal Laser Endomicroscopy for Brain Tumor Surgery in 50 Patients

Introduction: Fluorescein sodium confocal laser endomicroscopy (CLE) is a real-time in vivo intraoperative cellular resolution imaging technology. We evaluated the diagnostic capability and efficiency of the first clinically approved CLE system in brain tumor surgeries.

Methods: Fifty patients underwent brain tumor surgery were prospectively enrolled (28 gliomas, 5 meningiomas, 3 metastases, and 15 other pathologies). CLE images were interpreted by one CLE-experienced neuropathologist as lesional, nonlesional, or uninterpretable and compared to histology acquired at the same location under neuronavigation. Diagnostic accuracy of CLE imaging was calculated using permanent sections as the standard. The neuropathologist provided real-time image interpretation using a built-in telepathology consultation platform in 27 cases. Time spent on CLE imaging and achieving frozen section diagnosis was documented. Total cost of CLE imaging per case on a five-year, five-cases-per-week basis was compared to that of frozen section.

Results: 13535 interpretable images were acquired from 304 regions of interest (ROIs). The first informative images were acquired within 10.5 seconds after initiation of CLE imaging for each ROI. On average, CLE imaging with telepathology consultation took 3.9 minutes for each ROI, while frozen section yielded a diagnosis 28.1 minutes after tissue acquisition. Mean CLE imaging time per case was 8.6 minutes. Telepathology consultation extended CLE imaging per case time by 3.8 minutes (p = 0.008). Overall sensitivity and specificity of CLE imaging were 93% and 81%, respectively. The specificity differed significantly between core and margin ROIs in glioma cases (93% vs 50%, p=0.039). The cost of CLE imaging per case was comparable to frozen section biopsy of three samples.

Conclusion : The clinically approved CLE system allows intraoperative in vivo visualization of brain tumor histoarchitecture and identification of lesional tissue in real time, without the need for tissue biopsy. CLE combined with telepathology consultation appears to have a significant impact on operative workflow and cost-effectiveness.