Standardized bilateral thoracic ultrasound image comparison as a tool for the diagnosis of pneumothorax: a pilot exploratory study.

Abstract

Aim: Pneumothorax is a potentially life-threatening condition whose diagnosis can be challenging. Ultrasound chest examination is generally fast and user-friendly, but in non-expert hands or with uncooperative patients, it may still be difficult and time-consuming. Adding another tool to support the suspicion of pneumothorax might be useful, potentially enhancing the diagnostic accuracy of standard ultrasound chest examination. We evaluated the feasibility of standardized bilateral ultrasound image comparison as a potential new tool for pneumothorax diagnosis.

Materials and methods: We enrolled 60 subjects (30 with pneumothorax and 30 controls) and collected bilateral ultrasound images of their chests (each image contained one frame from the left lung and one from the right lung). Ten physicians (eight blinded to diagnosis) divided into five groups according to expertise evaluated the images for potential grayscale differences and/or horizontal artifacts between the two frames. All images were then analyzed with image analysis software for grayscale pixel assessment (one sub-analysis for the entire area under the pleural line, one for a 100-pixel-wide rectangle under the pleural line).

Results: All clinicians achieved good results in terms of diagnostic accuracy and inter-operator reliability, even those unexperienced in ultrasound. Mean, range, and median grayscale pixel ratio between the pneumothorax side and the healthy side in a single patient proved to be the most reliable parameters, reaching excellent sensitivity and specificity. Combining these parameters proved to be an excellent diagnostic tool (ROC area under curve = 1.00, p-value = 0.02).

Conclusions: Standardized bilateral thoracic ultrasound image comparison may be a potential new tool for the diagnosis of pneumothorax.