An endomicroscopic OCT for clinical trials in the field of ENT

Changes in the structure of the nasal mucosa can be a morphological biomarker and therefore helpful for diagnosis and follow-up of various pulmonary diseases such as asthma, cystic fibrosis and primary ciliary dyskinesia. In order to verify that microscopic optical coherence tomography (mOCT) is a valuable instrument for the investigation of those changes, an endoscopic OCT system with microscopic resolution (emOCT) was developed and built for clinical testing. The endoscope is based on a graded-index (GRIN) lens optic and provides a calculated lateral resolution of 0.7 µm and an axial resolution of 1.25 µm. The imaging depth was up to 500 µm in tissue; axially, a lateral range of approximate 250 µm could be covered. B-scans were acquired at 80 Hz with 512 pixels in lateral and 1024 pixels in depth-direction. The diameter of the endoscope decreases over a length of 8 cm from 8 mm at the beginning to 1.4 mm at the end and is small enough to observe the mucous membrane in the human nasal concha media and inferior down to the nasopharynx. The emOCT workstation was designed to meet German electrical, optical and biological safety standards. The applicability of the endoscope could be demonstrated in vivo. Mucus transport, glands, blood and lymphatic vessels could be visualized.