The 12-zone method involves dividing the chest into 6 zones demarcated by the anterior axillary and posterior axillary lines and then into upper and basal regions. This is repeated for the other side. 2 sides therefore 12 zones.
The characteristic findings included:
- Thickening of the pleural line with pleural line irregularity;
- B lines in a variety of patterns including focal, multifocal, and confluent;
- Consolidations in a variety of patterns including multifocal small, non-translobar, and translobar with occasional mobile air bronchograms;
- The appearance of A-lines during recovery phase
- Pleural effusions are uncommon.
They compared lung CT with lung ultrasound features in the table below
Table 1 CT and ultrasonographic features of COVID-19 pneumonia
Lung CT |
Lung ultrasound |
Thickened pleura |
Thickened pleural line |
Ground glass shadow and effusion |
B lines (multifocal, discrete, or confluent) |
Pulmonary infiltrating shadow |
Confluent B lines |
Subpleural consolidation |
Small (centomeric) consolidations) |
Translobar consolidation |
Both non-translobar and translobar consolidation |
Pleural effusion is rare. |
Pleural effusion is rare |
More than two lobes affected |
Multilobar distribution of abnormalities |
Negative or atypical in lung CT images in the super-early stage, then diffuse scattered or ground glass shadow with the progress of the disease, further lung consolidation |
Foca B lines are the main feature in the early stage and in mild infection; the alveolar interstitial syndrome is the main feature in the progressive stage and in critically ill patients; A-lines can be found in the convalescence; pleural line thickening with uneven B lines can be seen in patients with pulmonary fibrosis |