OCT can obtain high-resolution, cross-sectional microimages of tissue potentially allowing for optical biopsy to substitute for conventional excisional biopsy. The purpose of the present study is to investigate the capability of OCT to image the microstructure of the normal and abnormal bronchial tissue.
Equipment: OCT system; the OCT system of this study has been produced by Light Lab Imaging (Boston, USA). Preclinical examination: the OCT system was used in seven resected lung specimens which had been signed the informed consent for the OCT study. The OCT catheter was inserted from biopsy channel of the bronchoscope and evaluation of bronchial lumen was performed. The catheter directs the OCT beam radially and scans a circumferential pattern to generate a transluminal image. We collected OCT images of normal bronchus, primary tumors (2 cases of centrally located) and alveoli. All the images were captured and marked to identify the source of OCT imaging for later correlation with histology.
1) Normal bronchus; the bronchial mucosal layer appears homogenous in OCT image. Submucosal layer is relatively reflective due to the presence of extracellular matrix. A gap can be seen between the submucosa and smooth muscle layer and cartilage appears highly scattering below the muscle layer. 2) Alveoli; the uniform bronchial wall and the structure of alveoli containing air can be observed. 3) Bronchial tumor; nodular-infiltrative type squamous cell carcinoma is observed. The tumor is depicted by unevenly distributed high backscattering area and resultant loss of layer structure in the OCT image.CONCLUSIONS: Five layers were separately observed in normal bronchus by OCT image, as opposed to bronchial tumors which lacked a layered structure. OCT images were captured by OCT catheter probe inserted through the biopsy channel of bronchoscope, which was a good clinical simulation.
OCT should revamp the present strategies for endoscopic early diagnosis. Optical biopsy using by OCT system is considered to be useful in follow up to dysplasia as well as evaluation of therapeutic outcome.
M. Tsuboi, None.