J Korean Soc Radiol.  2011 Apr;64(4):341-350. 10.3348/jksr.2011.64.4.341.

Radiologic Review of an Outbreak of the Pandemic (H1N1) 2009 Virus Infection at a University Hospital in Seoul, Korea

• Choi SH
• Kang EY
• Kim JS
• Kim YK
• Woo OH
• Yong HS
• Oh YW

• KMID: 1443537
• DOI: http://doi.org/10.3348/jksr.2011.64.4.341

Abstract

PURPOSE
To assess the frequency of radiologic abnormalities and investigate the radiologic findings of patients with a pandemic (H1N1) 2009 virus infection at a University hospital in Seoul, Korea.
MATERIALS AND METHODS
In November 2009, 9,427 patients were tested for pandemic (H1N1) 2009 virus and 3,849 (41%) were positive. Among them, only 338 (9%) underwent chest radiographs and 13 (0.3%) received chest CT. Two radiologists retrospectively reviewed all the radiologic images.
RESULTS
Among the 338 patients, 287 (85%) were normal and 51 (15%) showed abnormalities. The frequency of abnormalities was significantly higher in children (41/212=19%) than in adults (10/126=8%) (p=0.005). Of them, 42 (82%) patients had airspace pneumonia, whereas the remaining patients showed a bronchopneumonia pattern. Unilateral (82%) involvement was more common than bilateral (18%) involvement. Among patients who received chest CT, 12 (92%) showed abnormalities, with bilateral (67%) and random (75%) involvement being more common. Ground-glass opacity (67%) and centrilobular nodules (58%) were the more common CT findings.
CONCLUSION
Only a small number of patients were critically ill enough to undergo further radiologic evaluation as a result of pandemic (H1N1) 2009 virus infection, and most patients had normal chest radiographs. Unilateral airspace pneumonia was the most common abnormality in patients infected with pandemic (H1N1) 2009 virus.

MeSH Terms

Adult
Bronchopneumonia
Child
Critical Illness
Humans
Influenza, Human
Korea
Pandemics
Pneumonia
Radiography, Thoracic
Retrospective Studies
Thorax
Tomography, X-Ray Computed
Viruses

Figure

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  Fig. 1 Chest PA (A) and lateral (B) views of a 4-year-old boy with a pandemic (H1N1) 2009 virus infection. It shows homogeneous consolidation (arrows) with air-bronchogram in right upper lobe. He did not have any laboratory evidence of other bacteria. This unilateral airspace pneumonia is the most common finding in our study.

• 

  Fig. 2 Chest PA (A) and lateral (B) views of an 8-year-old boy with a pandemic (H1N1) 2009 virus infection. There are patchy and small nodular opacities (arrows) prominently visible in the central right upper lobe. 17% of the children in our study showed this bronchopneumonia pattern.

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  Fig. 3 Chest PA view (A) and contrast enhanced CT scan performed 6 days later (B) of a 5-year-old boy with a pandemic (H1N1) 2009 virus infection (Patient 1). The chest radiograph showed airspace pneumonia in the right middle and lower lobes with right pleural effusion. The boy received a chest CT because of aggravation of pleural effusion. On the axial CT scan with a mediastinal window setting, consolidation was seen in the right lung (black arrows) with pleural effusion in the right hemithorax (white arrows). A chest tube was inserted (asterisk). The CT findings seemed extensive but he showed slow improvement on follow-up radiographs. One month later, the patient was discharged from the hospital.

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  Fig. 4 Chest PA view (A) and chest HRCT on the same day (B, C) of a 57-year-old male with a pandemic (H1N1) 2009 virus infection (Patient 11). The radiograph showed patchy and nodular opacities in the right lung, which were thought to be a bronchopneumonia pattern (arrows). In the chest CT scans, focal ground-glass opacity (GGO) (white arrows), consolidation (black arrow) and centrilobular nodules (asterisk) are seen in both lungs.

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