Visualising ventilation changes following endobronchial valve placement with x-ray velocimetry functional lung imaging.

Abstract

Objective: Endobronchial Valves are a minimally invasive treatment for emphysema. After bronchoscopic placement the valves reduce the flow of air into targeted areas of the lung, causing collapse, and allowing the remainder of the lung to function more effectively. This pilot study aims to demonstrate the capability and potential of a new imaging modality - X-ray Velocimetry - for detecting these changes to lung function. Approach: X-ray Velocimetry is a novel method that uses X-ray images taken during a breath to track lung motion, producing 3D maps of local ventilation. Healthy sheep received a CT scan and underwent X-ray Velocimetry imaging before and after endobronchial valves were placed in the lung. Sheep were imaged again when the endobronchial valves were removed after 14 days. Main results: X-ray Velocimetry enabled visualisation and quantification of a reduction of airflow to the areas downstream of the endobronchial valves, both in areas where collapse was and was not visible in CT. Changes to ventilation were also clearly visible in the remainder of the lungs. Significance: This preclinical study has shown X-ray Velocimetry is capable of detecting changes to ventilation caused by endobronchial valve placement, paving the way towards use in patients.