Some common features that may be encountered with specific respiratory viral infections
| Virus | Imaging features |
| Influenza | CXR: bilateral reticulonodular opacities, sometimes associated with poorly defined areas of consolidation, that can become confluent with time CT: GGOs interspersed with patchy consolidations; small and ill-defined centrilobular nodules can be seen [60] |
| Respiratory syncytial virus | Airway-centric pattern of disease characterised by tree-in-bud opacities, bronchial wall thickening and peribronchial consolidations [59, 61] |
| Adenovirus | CXR: most characteristic pattern is diffuse, bilateral bronchopneumonia associated with hyperinflation, especially in children; lobar atelectasis is also a common finding, with right upper lobe atelectasis more common in infants and left lower lobe atelectasis in older children [60] CT: typically presents as bilateral and multifocal GGOs associated with patchy consolidations (figure 2); occasionally a lobar or segmental pattern of involvement, which resembles that of bacterial infections, may be encountered [59] |
| Rhinovirus | Multiple, bilateral, patchy areas of GGO and consolidation, associated with interlobular septal thickening [59] |
| Human coronaviruses (SARS/MERS) | CXR: may be normal initially but rapid progression to multifocal consolidations commonly seen; predominant lower lobe involvement CT: multiple GGOs and consolidations; in the areas of GGO, thickening of the interlobular septa may be seen, resulting in a “crazy paving” pattern; subpleural and peribronchovascular distribution is typical [59, 62] |
| Parainfluenza | CT: multifocal GGOs is the most common appearance; small peribronchial nodes and patchy appearances can also be found [62] |
| Human metapneumovirus | CXR: generally depicts multilobular infiltrates CT: bilateral, multifocal, patchy GGOs and small ill-defined nodular opacities; consolidations present in <50% of patients [59, 62] |
| Measles | CXR: mixed reticular opacities and consolidations CT: the typical appearance is multifocal GGOs and consolidations; small peribronchial nodular opacities and thickening of the interlobular septa can also be encountered; hilar lymphadenopathies and pleural effusions frequently seen [59, 60] |
| Herpes simplex virus type 1 | CXR: patchy bilateral GGOs and consolidations that can have a lobular, subsegmental or segmental pattern of distribution CT: patchy lobular, segmental or subsegmental consolidations and GGOs, usually with a predominance of GGOs; pleural effusions are not uncommon [59, 62] |
| Varicella-zoster virus | CXR: multiple, small and ill-defined nodules that may become confluent CT: also multiple, small (5–10 mm) nodules, some with a surrounding halo of GGOs; patchy GGOs and areas of confluence of nodules can also be encountered; occasionally lesions may calcify and persist as numerous, randomly distributed, small calcifications [59, 62] |
| Cytomegalovirus | Bilateral, asymmetric and patchy GGOs associated with interlobular septal thickening; centrilobular nodules and consolidations can also be seen [59] |
| Epstein–Barr virus | Most frequent imaging finding is mediastinal lymphadenopathy CT: non-specific and includes diffuse or focal interstitial infiltrates [59, 62] |
| Hantavirus | Interstitial oedema that can rapidly progress to air-space consolidations CT: extensive bilateral GGOs and thickened interlobular septa typical; cardiomegaly and pleuro-pericardial effusions can also be seen [60, 62] |
CXR: chest radiography; CT: computed tomography; GGO: ground-glass opacity; SARS: severe acute respiratory syndrome; MERS: Middle East respiratory syndrome.