Small pneumothoraces can be difficult to detect on chest xrays. Overlying ribs, other bony structures, and soft tissue can obscure subtle findings. For a patient at risk for a small pneumothorax, you can use your digital radiology PACS system to improve your ability to spot them.
Trick of the Trade
Invert digital image of chest film
Standard digital radiography systems allow the user to manipulate images on the screen. Specifically there is an “invert image” icon.
By clicking on the button, black images appear white, and white images appear black. Using this Invert feature, bones, soft tissue, and vascular markings will be black, and lung parenchyma will be white. The pleural line of a pneumothorax, now a dark line on a white background with this inverted setting, is often better visualized using this technique.
Check out the inverted image of the CXR showing a subtle right-sided pneumothorax (just inferior to the orange arrows). If only all xrays had these arrows…