[A case report of rounded atelectasis on MRI]

A 73-year-old man was admitted to Toyama Red Cross Hospital, because of productive cough and right flank pain. His chest X-ray film and computed tomography (CT) showed pleural effusion and a mass shadow in the right lung area. On CT vessels and bronchi were seen curving toward the mass (comet tail sign), suggesting rounded atelectasis. Transthoracic lung biopsy under CT and echo guidance revealed suppurative pleuritis. MRI also showed the comet tail sign. Moreover, in the lesion, curling hypointense lines were observed on various slices. We describe how MRI facilitates the diagnosis of rounded atelectasis.