Journal List > J Korean Soc Radiol > v.64(4) > 1086926

Lee, Seon, Choi, Kim, Lim, Shin, Kim, and Park: High-resolution Computed Tomography Findings of H1N1 Influenza-Associated Pneumonia in Korea



To evaluate and compare the high-resolution computed tomography (HRCT) findings of patients with H1N1 influenza-associated pneumonia compared usual community acquired pneumonia (CAP), to determine whether there were any useful common HRCT findings predicting their prognosis.

Materials and Methods

HRCT findings of 31 patients (M:F = 16:15, mean age 42 yrs) with Influenza A (H1N1) infection were retrospectively reviewed for abnormal HRCT findings and compared to HRCT findings of CAP in matched patients. Patients were matched according to age and sex, from 2009 to January 2010.


The predominant HRCT findings of pneumonia consisted of areas of consolidation and/or ground-glass opacity (GGO) which showed no statistically significant differences when comparing the two groups. However, the abnormalities of H1N1-related pneumonia showed higher bilaterality and multilobar or multisegmental involvement compared with CAP (p < 0.05). Internal low attenuation or air-densities in pulmonary infiltration/or lymphadenopathy was observed only in patients with CAP (p < 0.05). HRCT findings in 8 patients with poor clinical outcome had bilaterality (p=0.015), multilobar, and multisegmental involvement.


The predominant HRCT findings of H1N1-related pneumonia were areas of consolidation and/or GGO. In addition, H1N1-related pneumonia showed higher bilaterality or multilobar/multisegmental involvement compared with CAP. The patients who presented bilaterality had a worse clinical outcome.

Figures and Tables

Fig. 1

H1N1 influenza-associated pneumonia in a 31-year-old woman with fever. A chest HRCT scan shows subsegmental consolidation (black arrow) in right middle lobe and diffuse bronchial wall thickening (white arrow) in both lower lobes, and small centrilobular nodules with linear branching opacities (arrow heads) in right lower lobe.

Fig. 2

HRCT patterns of abnormal parenchymal opacities in H1N1 associated pneumonia (black bar) and usual community acquired pneumonia (white bar) are consolidation, mixed pattern, or GGO. Each pattern of parenchymal opacities does not show statistically significant difference.

Fig. 3

H1N1 influenza-associated pneumonia in a 51-year-old woman with cough. A chest HRCT scan shows multifocal consolidations (black arrow) with mild surrounding ground glass attenuation (arrowhead) in both lower lobes with posterior predominance.

Fig. 4

H1N1 influenza-associated pneumonia in a 50-year-old woman with fever. An initial chest radiograph (A) shows multiple patchy areas of increased opacities in both lungs. Chest HRCT scan (B) shows multiple patchy areas of consolidations (open arrows in B) and ground glass attenuations (arrowhead in B) in both lungs.

Fig. 5

Usual community acquired pneumonia in 79-year-old male with fever and general weakness. Chest CT scans (A-C) show consolidation in right lower lobe (open arrow in A) containing areas of mottled air densities (open arrow in B) and necrotic low attenuation (open arrow in C, postcontrast enhanced mediastinal window setting). Bilateral pleural (white arrows in B) and pericardial effusion (white arrowhead in B) are also noted.

Table 1

Comparison of Radiologic Findings between the Patients with H1N1 Influenza Infection and the Patients with Usual Community Acquired Pneumonia (CAP), (n=31)


Note.─ *8 of the 31 H1N1 infected patients didn't show zonal predominance.

31 patients who have CAP didn't show any zonal predominance.

Table 2

Characteristic Image Findings and Clinical Features in the Patients with H1N1 Influenza Infection Who Needed Mechanical Ventilation


Note.─ *5 of 8 patients with mechanical ventilation therapy were died.

Table 3

Characteristic Image Findings in the Patients with H1N1 Influenza Infection Who Have Superimposed Other Bacterial Infection



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