PURPOSE: To determine the CT imaging findings of 4 common viral lower respiratory tract infections (LRTI) and any definable differences between the causative viruses.
METHODS: The imaging features of LRTI caused by Influenza, Respiratory Syncytial Virus (RSV), Parainfluenza (PIV) and Adenovirus over a 33-month period were reviewed by a radiologist blinded to clinical and diagnostic information. Subjects with viral LRTI's and bacterial co-infection were excluded from the analysis. Individual CT imaging features and the dominant pattern of infection were recorded for each examination. Imaging characteristics were compared between the four tested respiratory viruses.
RESULTS: Ninety-seven CT's were analyzed (56 influenza, 24 RSV, 11 Adenovirus, 6 PIV). No imaging findings were appreciated in approximately 1/3rd of patients. A Bronchitis-bronchiolitis pattern characterized by bronchial wall thickening and tree-in-bud opacities occurred in approximately 1/3rd of patients. A multifocal pneumonia pattern characterized by multifocal ground glass opacity or consolidation was noted in approximately 1/4 of patients and unifocal pneumonia characterized by unifocal consolidation, ground glass opacity or tree-in-bud opacities approximately 8% of patients. RSV and PIV predominantly caused a bronchitis-bronchiolitis pattern of infection, whereas adenovirus predominantly caused a multifocal pneumonia pattern of infection. Influenza frequently presented with normal appearing CT's, but because of its higher prevalence was the most common cause of all patterns of viral LRTI.
CONCLUSION: Viral LRTI have characteristic patterns of disease on CT imaging.
CLINICAL IMPLICATIONS: An understanding of the imaging appearance of viral lower respiratory tract infections can aid in the appropriate management of community acquired pneumonia and prevent the over utilization of antibiotics.
DISCLOSURE: Wallace Miller, No Financial Disclosure Information; No Product/Research Disclosure Information