Chest computed tomographic imaging characteristics of viral acute lower respiratory tract illnesses: a case-control study.

Objective: This study aimed to determine whether computed tomographic (CT) findings can distinguish viral lower respiratory tract illness (LRTI) from other conditions. Methods: Three radiologists reviewed CT images of patients with LRTI who underwent testing for respiratory viral infection. Imaging findings in subjects with positive viral assays were compared with subjects with negative assays. Results: Of 334 subjects, 93 were positive for viral LRTI. Tree-in-bud opacities and bronchial wall thickening were observed more often in subjects with viral LRTI (P G 0.05). Multifocal airspace disease occurred with similar frequency in both groups. Diffuse airspace opacification was negatively associated with viral LRTI. Pleural effusion was observed more often among subjects without viral LRTI (P G 0.001). Conclusions: Airway inflammatory changes such as tree-in-bud opacities, bronchial wall thickening, and peribronchiolar consolidation are associated with community-acquired viral LRTI. Recognition of these findings should prompt testing for viral infection. Multifocal consolidation is commonly found in cases of viral LRTI but is nonspecific.