Protocol for a pilot feasibility, safety and efficacy study of artificially introducing an air-pleura interface for detection of pleural nodules by computed tomography: the AIR study

Abstract

Abstract Background: Pleural effusions are common and can arise from many causes including primary or metastatic malignancies. Computed tomography (CT) is part of the routine workup for pleural effusions especially if pleural fluid analysis fails to show an underlying cause. CT can help detect pleural abnormalities such as thickening or nodules and allow imaging guided percutaneous biopsies. Otherwise surgical procedures are often required to obtain histological specimens but have inherent risks. The presence of air in the pleural cavity (eg with trapped lung) has been shown in a case series to enhance CT detection of pleural abnormalities. The AIR study is a prospective, pilot, proof-of-concept study to assess the feasibility and safety of instilling air intrapleurally to create an air-pleura interface during CT imaging, and the efficacy of this artificial pneumothorax in aiding CT detection of pleural abnormalities. Methods: This study will recruit 40 patients with suspected or proven malignant pleural effusions that have a chest tube (including indwelling pleural catheter) in-situ and no pre-existing radiological evidence of advanced pleural abnormalities. A standard CT scan with pleural phase contrast enhancement will be performed. Air will be instilled via the chest tube to introduce an artificial air-pleura interface and a second (non-contrast) CT chest scan will be performed in the prone position. The air will be immediately aspirated after the procedure. The aims of this study are to determine 1) the feasibility and safety of introducing an air-pleura interface using a pre-defined protocol and 2) its effectiveness in detecting additional pleural abnormalities. Discussion: The AIR study is the first study to evaluate the feasibility, safety and efficacy of creating an artificial air-pleura interface to enhance detection of pleural abnormalities by CT. Improvements in detection may inform imaging-guided tissue sampling, avoid more invasive tissue acquisition procedures, and add to the assessment of pleural disease burden.