Instant On-Site Histological Analysis of Fresh Lung Tumor Tissue Using Third and Second Harmonic Generation Microscopy

Introduction: In (suspected) lung cancer patients undergoing surgery, immediate feedback on the nature of the excised tissue and the surgical margin can be key in deciding the extent of the surgical resection. Third and second harmonic generation (THG/SHG) microscopy is a label-free, transportable, ex-vivo imaging technique that provides 3D images with subcellular details within seconds. Methods: In patients with suspected or proven lung cancer, samples of unprocessed tumor and healthy tissue were imaged with the THG/SHG microscope immediately after excision. Subsequently the tissue specimens were histologically analyzed and compared with the THG/SHG images. Results: In 4 patients healthy and tumor tissue (n=3 adenocarcinoma, n=1 carcinoid) was imaged with the THG/SHG microscope. Immediate high-quality images were obtained in all specimens. Malignancy could be detected as a disrupted alveolar pattern and an increased density of cellular structures with enlarged nuclei. Clear distinction between malignant and surrounding healthy tissue could be made. Conclusion: We present the first ex-vivo THG/SHG images, worldwide, of lung cancer tissue acquired with a mobile THG/SHG microscope. The very detailed images distinguish between healthy and malignant excised tissue. In the future, instant on-site histologic analysis using THG/SHG microscope might improve surgical/bronchoscopical outcomes.