Atelectasis

Question 1

(A) Most common CT features of rounded atelectasis in chronic inflammatory pleural effusions (chylothorax and pyothorax) in cats and dogs (T.H. Tran, 2022)

Answer 1

92%:
- comet tail signs (bundles of bronchi / vessels coalescing into the pulmonary nodules
- creating acute angle with the adjoining visceral pleura
- Occupying gravity dependent regions of the lungs
- Blurred hilar margins with shaper pleural margins
83%: air bronchograms

Question 2

(A) Less common CT features of rounded atelectasis in chronic inflammatory pleural effusions (chylothorax and pyothorax) in cats and dogs (T.H. Tran, 2022)

Answer 2

64%: homogeneous contrast enhancement, rest varied pattern.
61%: volume loss of the affected lung lobe

Question 3

No CT features of rounded atelectasis in chronic inflammatory pleural effusions (chylothorax and pyothorax) in cats and dogs (T.H. Tran, 2022)

Answer 3

• No predisposition for lung lobe location

Question 4

No CT features of rounded atelectasis in chronic inflammatory pleural effusions (chylothorax and pyothorax) in cats and dogs VS malignant neoplasia (T.H. Tran, 2022)

Answer 4

Malignant neoplasia:
- Occasional pleural tags –> linear ST attenuations bridging the tumour to the adjacent pleura, caused by septal thickening due to lymhatic obstruction, edema or malignant spread
- Intralesional gas / mineralisation foci
- Local invasion into the bronchi / vessels /adjacent lung lobes

Question 5

(A/T) Is there minimal atelectasis and poorly aerated lung on thoracic CT images of normal dogs acquired under sedation? (Hunt, 2021)

Answer 5

Yes, using sedation to complete canine
thoracic CT does not itself lead to alterations of lung attenuation and may confer less
hypoinflation and atelectasis than general anesthesia