Passive atelectasis on magnetic resonance imaging

Magnetic resonance image (MRI; transverse plane with steady-state free precession) of a patient with left ventricular failure that shows bilateral free-layering pleural effusions (arrow) and bilateral lower lobe passive atelectasis (thick arrow). The pleural effusions show high signal and the dependent bilateral lower lobe atelectases float on the pleural effusion and have intermediate signal. The normal, aerated lung is devoid of signal (arrowhead).