D. Lung Abscess
Image shows:Frontal chest radiograph showing clusters of cystic spaces containing air-fluid levels (arrows) in the left mid and lower zones due to retained secretions in dilated bronchioles in bronchiectasis.
- The air-fluid levels within the cystic spaces represent retained secretions within the dilated bronchioles.
- A CT scan was performed as it better assesses the extent and severity of the disease.
- String of cysts appearance representing cystic dilatation of bronchioles
- Thickening of bronchial wall indicating on-going inflammatory change
- Air-fluid level representing retained bronchial secretions
- Majority of bronchiectasis occurs peripherally in lower lobes.
- Unusual sites of involvement raise the suspicion of certain aetiologies of bronchiectasis, e.g. upper zone predominance in cystic fibrosis, proximal central zone involvement in allergic bronchopulmonary aspergillosis.
- In the past bronchogram was regarded as the gold standard for diagnosis by demonstrating dilated bronchioles outlined by contrast. However, it has been replaced by CT as it offers a noninvasive method for diagnosis.
- Radiological signs on CT of less severe form of bronchiectasis include
- ‘Tram-track’ sign due to dilated bronchioles with its accompanying vessel
- ‘Signet-ring’ sign representing dilated bronchiole closely related to its adjacent vessel