Tuberc Respir Dis.  2011 May;70(5):397-404.

Pandemic Influenza A/H1N1 Viral Pneumonia without Co-Infection in Korea: Chest CT Findings

• Son JS
• Kim YH
• Lee YK
• Park SY
• Choi CW
• Park MJ
• Yoo JH
• Kang HM
• Lee JH
• Park B

Abstract

BACKGROUND
To evaluate chest CT findings of pandemic influenza A/H1N1 pneumonia without co-infection.
METHODS
Among 56 patients diagnosed with pandemic influenza A/H1N1 pneumonia, chest CT was obtained in 22 between October 2009 and Februrary 2010. Since two patients were co-infected with bacteria, the other twenty were evaluated. Predominant parenchymal patterns were categorized into consolidation, ground glass opacity (GGO), and mixed patterns. Distribution of parenchymal abnormalities was assessed.
RESULTS
Median age was 46.5 years. The CURB-65 score, which is the scoring system for severity of community acquired pneumonia, had a median of 1. Median duration of symptoms was 3 days. All had abnormal chest x-ray findings. The median number of days after the hospital visit that Chest CT was performed was 1. The reasons for chest CT performance were radiographic findings unusual for pneumonia (n=13) and unexplained dyspnea (n=7). GGO was the most predominant pattern on CT (n=13, 65.0%). Parenchymal abnormalities were observed in both lungs in 13 cases and were more extensive in the lower lung zone than the upper. Central and peripheral distributions were identified in ten and nine cases, respectively. One showed diffuse distribution. Peribronchial wall thickening was found in 16 cases. Centrilobular branching nodules (n=7), interlobular septal thickening (n=4), atelectasis (n=1), pleural effusion (n=5), enlarged hilar and mediastinal lymph nodes (n=6 and n=7) were also noted.
CONCLUSION
Patchy and bilateral GGO along bronchi with predominant involvement of lower lungs are the most common chest CT findings of pandemic influenza A/H1N1 pneumonia.

Keyword

Influenza A Virus, H1N1 Subtype; Tomography, X-Ray Computed; Pandemics; Pneumonia; Influenza, Human

MeSH Terms

Bacteria
Bronchi
Coinfection
Dyspnea
Glass
Humans
Influenza A Virus, H1N1 Subtype
Influenza, Human
Lung
Lymph Nodes
Pandemics
Pleural Effusion
Pneumonia
Pneumonia, Viral
Pulmonary Atelectasis
Thorax
Tomography, X-Ray Computed

Figure

• 

  Figure 1 An 18-year-old male patient with pandemic influenza A/H1N1 pneumonia. Chest CT scans obtained in the level I (A), level II (B), level III (C) and level IV (D) showed bilateral and multi-focal ground glass opacities. Left pleural effusion was also found (white arrow). CT: computed tomography.

• 

  Figure 2 A 27-year-old male (A) and a 42-year-old female (B) with pandemic influenza A/H1N1 pneumonia. Chest CT revealed that multiple ill-defined ground glass opacities in middle to lower lungs with bronchial wall thickening (A, B) (white arrow). Right pleural effusion was also seen (A) (black arrow). CT: computed tomography.

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  Figure 3 A 55-year-old male patient with pandemic influenza A/H1N1 pneumonia. Chest CT obtained 4 days after onset of symptoms showed a diffuse mixed pattern with ground glass opacities and consolidation in the right lower lobe. CT: computed tomography.

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