Definition: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
Input: Abstract: Foreign body aspiration in children is frequently associated with unilateral emphysema or atelectasis on chest x-ray. Two cases are reported of tracheal or bilateral foreign bodies in which the original chest x-rays were read as normal, but the history was suggestive of the foreign body aspiration. Early bronchoscopy can prevent the long-term morbidity that results from unrecognized tracheobronchial foreign bodies.

Thoracic Radiography