A total of 99 examinations were reviewed, 52 chest x-rays and 47 CT chest examinations. The predominant radiographic pattern on both imaging modalities was ground glass opacification (68/99; 69%) and majority (61.6%) were peripherally distributed and in the lower lobes (74.7%). A total of 12 examinations; (9 chest x-rays and 3 CT examinations) did not have features of pneumonia. Pleural effusion and lymphadenopathy was present in less than 10% of patients. The majority of patients (39.4%) had mild severity of pneumonia as assessed on radiographs and CT scan. These baseline characteristics are summarized in Table 1.
Table 1
Baseline characteristics of the chest x-ray and CT findings and radiological impression
| Total | Chest Radiograph | CT Chest |
(N = 99) | (N = 52) | (N = 47) |
Patterns of Pneumonia | Consolidation | 25 | 25.3% | 11 | 21.2% | 14 | 29.8% |
Ground glass | 68 | 68.7% | 29 | 55.8% | 39 | 83.0% |
No Opacities | 12 | 12.1% | 9 | 17.3% | 3 | 6.4% |
Nodular | 16 | 16.2% | 10 | 19.2% | 6 | 12.8% |
Reticular | 28 | 28.3% | 9 | 17.3% | 19 | 40.4% |
Reticulonodular | 22 | 22.2% | 17 | 32.7% | 5 | 10.6% |
Predominant Pattern | Consolidation | 8 | 8.1% | 5 | 9.6% | 3 | 6.4% |
Ground glass | 57 | 57.6% | 23 | 44.2% | 34 | 72.3% |
Nodular | 3 | 3.0% | 3 | 5.8% | 0 | 0.0% |
Reticular | 4 | 4.0% | 2 | 3.8% | 2 | 4.3% |
Reticulonodular | 15 | 15.2% | 10 | 19.2% | 5 | 10.6% |
No Opacities | 12 | 12.1% | 9 | 17.3% | 3 | 6.4% |
Distribution of Opacities | Central | 36 | 36.4% | 21 | 40.4% | 15 | 31.9% |
Diffuse | 32 | 32.3% | 17 | 32.7% | 15 | 31.9% |
Peripheral | 61 | 61.6% | 26 | 50.0% | 35 | 74.5% |
Predominant Distribution of Opacities | Central | 17 | 17.2% | 12 | 23.1% | 5 | 10.6% |
Diffuse | 21 | 21.2% | 13 | 25.0% | 8 | 17.0% |
Peripheral | 49 | 49.5% | 18 | 34.6% | 31 | 66.0% |
No Opacities | 12 | 12.1% | 9 | 17.3% | 3 | 6.4% |
Location of Opacities | Left Lower Lung | 64 | 64.6% | 24 | 46.2% | 40 | 85.1% |
Left Upper Lung | 58 | 58.6% | 19 | 36.5% | 39 | 83.0% |
Right Lower Lung | 79 | 79.8% | 36 | 69.2% | 43 | 91.5% |
Right Middle Lung | 59 | 59.6% | 20 | 38.5% | 39 | 83.0% |
Right Upper Lung | 61 | 61.6% | 20 | 38.5% | 41 | 87.2% |
Predominant Location of Opacities | Lower lung | 74 | 74.7% | 39 | 75.0% | 35 | 74.5% |
Upper lung | 13 | 13.1% | 4 | 7.7% | 9 | 19.1% |
No Opacities | 12 | 12.1% | 9 | 17.3% | 3 | 6.4% |
Fibrosis | No | 81 | 81.8% | 49 | 94.2% | 32 | 68.1% |
Yes | 18 | 18.2% | 3 | 5.8% | 15 | 31.9% |
Septal Thickening | No | 62 | 62.6% | 43 | 82.7% | 19 | 40.4% |
Yes | 37 | 37.4% | 9 | 17.3% | 28 | 59.6% |
Pleural Effusion | No | 90 | 90.9% | 46 | 88.5% | 44 | 93.6% |
Yes | 9 | 9.1% | 6 | 11.5% | 3 | 6.4% |
Location of Pleural Effusion | Left | 1 | 11.1% | 1 | 16.7% | 0 | 0.0% |
Right | 6 | 66.7% | 5 | 83.3% | 1 | 33.3% |
Bilateral | 2 | 22.2% | 0 | 0.0% | 2 | 66.7% |
Lymphadenopathy | No | 93 | 93.9% | 52 | 100.0% | 41 | 87.2% |
Yes | 6 | 6.1% | 0 | 0.0% | 6 | 12.8% |
Locations of Lymphadenopathy | Hilar | 3 | 50.0% | 0 | 0.0% | 3 | 50.0% |
Mediastinal | 4 | 66.7% | 0 | 0.0% | 4 | 66.7% |
Predominant Location of Lymphadenopathy | Hilar | 2 | 33.3% | 0 | 0.0% | 2 | 33.3% |
Mediastinal | 4 | 66.7% | 0 | 0.0% | 4 | 66.7% |
Severity of Pneumonia | No pneumonia | 14 | 14.1% | 10 | 19.2% | 4 | 8.5% |
Mild | 39 | 39.4% | 22 | 42.3% | 17 | 36.2% |
Moderate | 22 | 22.2% | 7 | 13.5% | 15 | 31.9% |
Severe | 24 | 24.2% | 13 | 25.0% | 11 | 23.4% |
Radiologist Diagnosis | COVID 19 | 49 | 49.5% | 15 | 28.8% | 34 | 72.3% |
Influenza | 29 | 29.3% | 20 | 38.5% | 9 | 19.1% |
No pneumonia | 14 | 14.1% | 10 | 19.2% | 4 | 8.5% |
Other pneumonia | 7 | 7.0% | 7 | 13.5% | 0 | 0.0% |
CORADS Score | 1 | 12 | 12.1% | 9 | 17.3% | 3 | 6.4% |
2 | 31 | 31.3% | 22 | 42.3% | 9 | 19.1% |
3 | 9 | 9.1% | 7 | 13.5% | 2 | 4.3% |
4 | 8 | 8.1% | 7 | 13.5% | 1 | 2.1% |
5 | 39 | 39.4% | 7 | 13.5% | 32 | 68.1% |
Laboratory diagnosis | COVID-19 | 77 | 77.8% | 37 | 71.2% | 40 | 85.1% |
Influenza | 22 | 22.2% | 15 | 28.8% | 7 | 14.9% |
The radiographic pattern of pneumonia was associated with the etiology of pneumonia (COVID-19 or influenza pneumonia) p-value <0.001 (Table 2). The ground glass was more common in COVID-19 diagnosis whereas the reticulonodular was more common in the Influenza diagnosis.
Table 2 Association of radiographic patterns and the type of pneumonia shows most patients with COVID-19 pneumonia had ground glass opacification compared to reticulonodular opacities in influenza pneumonia.
|
|
Laboratory diagnosis
|
P Value
|
|
|
COVID-19
|
Influenza
|
Predominant Pattern
|
Consolidation
|
2 (2.6%)
|
6 (27.3%)
|
<0.001
|
Ground Glass
|
51 (66.2%)
|
6 (27.3%)
|
Nodular
|
2 (2.6%)
|
1 (4.5%)
|
Reticular
|
3 (3.9%)
|
1 (4.5%)
|
Reticulonodular
|
8 (10.4%)
|
7 (31.8%)
|
Normal
|
11 (14.3%)
|
1 (4.5%)
|
The lower lobes were the predominant location of radiographic opacities for both COVID-19 (74.0%) and influenza pneumonia (77.3%). 14.3% of patients with COVID 19 had normal imaging compared to 4.5% of influenza pneumonia patients.
Patients with reticulonodular opacities with background ground glass opacification had a 91% reduction in the odds of having COVID-19 pneumonia (CI: 0.02-0.037; p value=0.001).
Table 3 Association of radiographic location and the type of pneumonia shows predominant lower lobe predilection in both COVID 19 and influenza pneumonia.
|
|
Laboratory diagnosis
|
P Value
|
|
|
COVID-19
|
Influenza
|
Predominant Location
|
Lower Lung
|
57 (74.0%)
|
17 (77.3%)
|
0.384
|
Upper Lung
|
9 (11.7%)
|
4 (18.2%)
|
Normal
|
11 (14.3%)
|
1 (4.5%)
|
Ground glass opacification had the highest sensitivity (89.5%) and negative predictive value (72.7%) in identification of COVID-19 pneumonia. Reticulonodular opacities on the other hand had the highest sensitivity (53.3%) and negative predictive value (68.2%) for identification of influenza pneumonia (Table 4).
Table 4 Diagnostic accuracy of the two predominant radiographic patterns showed high sensitivity and negative predictive value (NPV) of ground glass opacities for diagnosing COVID-19 pneumonia and moderate sensitivity and NPV of reticulonodular opacities for diagnosing influenza pneumonia.
Pneumonia Type
|
Overall Pattern
|
Sensitivity
|
Specificity
|
PPV
|
NPV
|
COVID-19 Vs Influenza
|
Ground Glass
|
89.47%
|
38.10%
|
66.23%
|
72.73%
|
Reticulonodular
|
53.33%
|
17.86%
|
10.39%
|
68.18%
|
Radiographic CORADS scores of 4 and 5 were associated a diagnosis of COVID-19 pneumonia with 59.8% of COVID-19 cases having a score of 4 or 5. The majority (90.9%) of Influenza pneumonia cases had a CORADS score of 2 and 3 on a radiographic assessment (table 5 and figure 1).
Table 5 Comparison of CORADS score and laboratory diagnosis of pneumonia shows higher CORADS scores (4 and 5) for COVID-19 pneumonia and lower score (2) for influenza pneumonia.
|
|
Laboratory diagnosis
|
P Value
|
|
|
COVID-19
|
Influenza
|
CORADS Score
|
1
|
11(14.3%)
|
1 (4.5%)
|
< 0.001
|
2
|
14(18.2%)
|
17 (77.3%)
|
3
|
6 (7.8%)
|
3 (13.6%)
|
4
|
8 (10.4%)
|
0 (0.0%)
|
5
|
38(49.4%)
|
1 (4.5%)
|
The inter-reader agreement between the two radiologists comparing the radiological impression and the final laboratory diagnosis was almost perfect with kappa score of 0.947 (p value <0.001).