A pleural ultrasound image of a collapsed lung surrounded by pleural fluid ("jellyfish sign") may correspond to an intrapericardial mass.

Lung ultrasound has been shown to be a valuable diagnostic tool. It has become the main way to get to the diagnosis of pleural effusion with much more specificity and sensibility than the x-ray. The diagnosis of pleural effusion with ultrasound is easily obtained after the visualization of hypoechoic fluid surrounding the lung.