Confocal laser microscopy without fluorescent dye in minimal-invasive thoracic surgery: an ex-vivo pilot study in lung cancer

Abstract

Cancer will be the leading cause of death in a few decades. In line with minimal invasive lung cancer surgery, surgeons loose most of their tactile tissue information and need an additional tool of intraoperative tissue navigation during surgery. Confocal laser microscopy is a well-established method of tissue investigation. In this ex-vivo pilot study, we evaluated an endoscopic confocal laser microscope (eCLM) that does not need any fluorescent dye as a diagnostic tool in non-malignant and malignant pulmonary tissue and distal stapler resection margins, respectively. In seven cases, an eCLM was used for examining pulmonary tissue ex-vivo. Images of non-malignant and non-small cell lung cancer tissue and distal stapler resection margins were characterized in terms of specific signal-patterns. No fluorescent dye was used. Correlations to findings in conventional histology were systematically recorded and described. Healthy lung tissue showed hyperreflectoric alveolar walls with dark alveolar spaces. Hyperreflective nets indicated the tumor stroma; whereas the hyperreflective areas indicated the tumor cell clusters. Compared to adenocarcinoma tissue, tissue from squamous cell carcinoma showed more distinctive hyperreflective stroma nets. eCLM characteristics seen in non-malignant and malignant tissue were also visible in distal stapler resection margins and so therefore it was feasible to distinguish between healthy lung tissue and lung cancer. This pilot study shows that the assessment of pulmonary tissue with this eCLM for minimally invasive surgical approach without any fluorescent dye is feasible. It enables to differentiate between benign and malignant tissue in pulmonary specimen by easy to evaluate and reproducible parameters.