This study aimed to retrospectively evaluate the computed Ltomographic (CT) appearance of cases of swine-origin influenza A(H1N1) viral infection (S-OIV) in immunocompetent and immunocompromised patients confirmed with reverse transcription-polymerase chain reaction and to determine whether the timing of CT relative to the onset of symptoms affected the overall imaging appearance.
A total of 23 patients (15 men and 8 women) from 2 tertiary care centers formed the final study population. Patients were divided into 2 groups based on their immune status: group 1 (n = 14) were patients who were immunocompromised, whereas group 2 (n = 9) were patients who were immunocompetent. The radiologic appearances of pulmonary abnormalities, distribution, and extent of involvement on the initial chest CT scan were documented, and correlation with the onset of symptoms was performed.
The most common CT pattern in both groups of S-OIV patients was ground-glass opacities and consolidation (group 1, 86%; group 2, 71%) in a bilateral, subpleural, and peribronchovascular pattern. Small airways were seen only in a minority of patients (group 1, 7%; group 2, 11%). Onset of symptoms to time of CT showed a mean duration of 9.7 days in group 1 and 6.7 days in group 2 and did not affect the overall imaging appearance.
The most common abnormalities on CT scans of both immunocompetent and immunocompromised S-OIV patients were ground-glass opacities and consolidation in a bilateral, subpleural, and peribronchovascular distribution, resembling organizing pneumonia. This appearance was seen regardless of the timing of CT relative to the onset of symptoms.
From the *Department of Radiology, Vancouver General Hospital; †Department of Radiology and ‡Infection Prevention and Control, St. Paul's Hospital, Providence Health Care, Vancouver, British Columbia, Canada; and §Radiology Department, King AbduAziz University Hospital, Jeddah, Kingdom of Saudi Arabia.
Received for publication April 13, 2011; accepted June 29, 2011.
Reprints: Tracy M. Chandler, MD, Department of Radiology, Vancouver General Hospital, 899 W 12th Ave, Vancouver, British Columbia, Canada, V5Z 1M9 (e-mail: firstname.lastname@example.org).
Dr Leipsic receives research support from GE Healthcare and serves on the medical advisory board and speaker's bureau for GE Healthcare. All the other authors have no disclosures.
The authors did not receive grants or other assistance for this study.