A Study Of Lung Bronchioles Imaging By Micro-imaging Fiber

Background: Although bronchiolar diseases, including occlusivebronchiolitis, follicular bronchiolitis, and diffuse panbronchiolitis, are notclosely tracked in China, they are common and hard to diagnose, whichlimits the progress of research and threatens human health and life. Hence,there is an increasing need to evaluate and manage bronchiolar diseases.With the development of imaging modalities, both computedtomography (CT) and positron emission tomography (PET) are playing agreater role in the evaluation of peripheral airways. The CT scan is veryuseful, but it lacks the sensitivity and specificity necessary to definitivelyestablish a diagnosis on its own. Similarly, although PET is more sensitivethan CT in identifying lesions in the peripheral segments of the lung, thereare too many false positives to allow treatment decisions to be consistentlymade based on PET imaging alone, and it is too expensive to widely applyin clinic, especially in developing countries.The diagnosis of a central pulmonary lesion still relies on pathologyresults. This allows for a clear diagnosis and pathological classification,which can guide treatment. Bronchofiberscopes of different diameters have been used to evaluate solitary pulmonary nodules and masses for more than30years. Patients with such nodules frequently undergo transbronchialbiopsy under fluoroscopic guidance. However, endoscopic informationoften fails to successfully detect peripheral airways smaller than2mm indiameter. In addition, due to challenging technology and the potential forsevere complications, the thoracoscopy is not commonly used as adiagnostic tool alone.These diagnostics play a key role in treatment decisions, but they arepoor at inspecting small lesions (<1mm). Direct viewing of the peripheralairways would provide higher-level endoluminal information for thediagnosis of bronchiolar diseases, such as acute bronchiolitis,bronchioloalveolar carcinoma, occlusive bronchiolitis,follicular bronchiolitis, diffuse panbronchiolitis, childhood asthma, andmineral dust airways diseases. Therefore, a new instrument was urgentlyneeded to solve these problems.In this study, a micro-imaging fiber optic bronchoscope (OD=0.82mm) was designed to obtain images of pig lung bronchioles（less than1mm in diameter）in vitro, and used to assess the feasibility and safety forviewing the peripheral airways (<1mm) in canines. PART I A STUDY OF LUNG BRONCHIOLES IMAGING BYMICRO-IMAGING FIBER IN VITROObjective：To explore the feasibility of micro-imaging fiber system toobtain images of pig lung bronchioles（less than1mm in diameter）in vitro.Methods: The throat of fresh pig lung in vitro was inserted amicro-imaging fiber (OD=0.82mm), and connected a non-invasiveventilation settings for CPAP (Continuous Positive Airway Pressure) mode.Then, images of levels of bronchioles anatomy, mucosal color, trachealsecretions were observed and recorded. Stop the experiment oncemicro-imaging fiber was hard to insert to the distal bronchial. Fixed themicro-imaging fiber and bronchial diameter could be obtained by thethree-dimensional reconstruction.Results: According to the three-dimensional reconstruction ofbronchioles, the new apparatus can probe into small airways considerablyperipheral (<1mm).Conclusion: The device can obtain images of pig lung bronchioles(＜1mm) in vitro, which provides a basis for obtaining lung bronchiolesimages in vivo, is expected to provide a new platform for the diagnosis ofbronchiolar diseases. PART II FEASIBILITY AND SAFETY OF FIBER OPTICMICRO-IMAGING IN CANINE PERIPHERAL AIRWAYSPURPOSE: To assess the feasibility and safety of imaging canineperipheral airways (<1mm) with an experimental micro-imaging fiberoptic bronchoscope.METHODS: Twenty healthy dogs were scoped with a micro-imagingfiber optic bronchoscope (0.82mm). Images at various levels of thebronchioles, mucosal color, and tracheal secretions were recorded. Theapparatus was stopped once it was hard to insert into the distal bronchiole.CT imaging was performed simultaneously to monitor progression. Thesafety of the device was evaluated by the heart rate (HR), respiratory rate(RR), mean artery pressure (MAP), peripheral oxygen saturation (SpO2)and arterial blood gases (partial pressure of arterial carbon-dioxide, PaCO2,partial pressure of arterial oxygen, PaO2, and blood pH).RESULTS:(1) According to the CT scan, the micro-imaging fiberwas able to access the peripheral airways (<1mm) in canines.(2) Therewas no significant change in the values of HR, MAP, pH and PaCO2duringthe procedure (P>0.05). Comparing pre-manipulation andpost-manipulation values, SpO2(F=13.06, P <0.05) and PaO2(F=3.01, P=0.01) were decreased, whereas RR (F=3.85, P <0.05) was elevated during the manipulation.(3) Self-limited bleeding was observed in one dog;severe bleeding did not occur.CONCLUSION: Although the new apparatus has little effect on SpO2,PaO2and RR, it can probe into small peripheral airways (<1mm), whichmay provide a new platform for the early diagnosis of bronchiolar diseases.