gms | German Medical Science

Objective: The reliable identification of tumor margins is still a challenge in neurosurgery. In the past, attempts in diagnostics of tumor borders using intravital confocal microscopy were often limited by temporal factors and instrumental effort. We investigated the potential benefits of a novel confocal laser endomicroscope for identification of tumor margins in vitro.

Methods: A prototype of a novel endomicroscope with a 488nm laser was used for analyses. Several samples of fresh tumor tissue from glioblastoma and cerebral metastases were stained with fluorescein. To verify reliability of cell density and morphology estimation by fluorescein staining, nuclei of corresponding tissue samples were stained and compared to fluorescein stainings. Subsequently, a cohort of 15 patients with high proliferative brain tumors (glioblastoma, metastases) was analyzed in order to identify tumor vs. non-tumor tissue samples using the abovementioned procedure. Following, the samples were analyzed by routine neuropathology.

Results: Using the laser endomicroscope images of sub-cellular level with diagnostic quality could be prepared. Acquisition-time for the images was 3 to 10 seconds, depending on the cell density. Cell density could be reliably estimated by fluorescein staining as compared to nuclear staining. Altogether, confocal imaging correlated strikingly well with routine pathologic findings and tumor tissue could be identified correctly.

Conclusion: The novel laser endomicroscope offers the possibility for real-time intra-vital detection of tumor tissue in glioblastoma and brain metastases. Thereby it has the potential to improve resection grades of cerebral tumors by fast and reliable visualization of tumor histopathologic features. Nevertheless, in vivo studies need to be carried out as soon as the endomicroscope will be approved for in vivo use.