TABLE 2.

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.