CT Findings in Recurring Pneumothorax
CT scanning is recommended for patients with recurrent pneumothorax to identify underlying lung abnormalities such as blebs and bullae, which are found in up to 90% of cases at thoracoscopy and up to 80% of cases on CT scanning. 1
Key CT Findings in Recurrent Pneumothorax
Anatomical Abnormalities
- Subpleural blebs and bullae: Present in up to 80% of cases on CT scanning 1
- Location: Predominantly in the apical regions of the lungs
- Size: Variable (can be classified and scored based on size)
- Number: Multiple blebs correlate with higher recurrence rates 2
Dystrophic Changes
- CT-based lung dystrophy severity score (DSS) can help predict recurrence risk 3
- Higher DSS values correlate with higher 5-year recurrence rates in conservatively treated patients 3
- Patients can be stratified into low and high-grade risk groups based on CT findings 3
Signs of Active Air Leak
- Discontinuity of visceral pleura may indicate a bronchopleural fistula 4
- In specialized CT techniques using saline solution and vocalization:
- Bubble shadows (seen in most cases with small pleural fistulae)
- Air-fluid levels in bullae (seen with larger fistulae)
- Ground-glass attenuation areas in pulmonary parenchyma 5
Clinical Applications of CT in Recurrent Pneumothorax
Diagnostic Indications
CT scanning is specifically recommended in the following scenarios:
- When differentiating pneumothorax from complex bullous lung disease 1, 6
- When aberrant chest tube placement is suspected 1, 6
- When plain chest radiographs are obscured by surgical emphysema 1, 6
- For evaluating patients with recurrent pneumothoraces 1
Risk Stratification
- CT findings can guide management decisions after first episode of pneumothorax 3
- Patients with lesions exceeding one bleb may benefit from early surgical intervention 3
- After video-assisted thoracic surgery (VATS), preoperative CT findings are less predictive of recurrence 3
Imaging Protocol Considerations
Standard Approach
- CT is the most accurate method for quantifying pneumothorax size (sensitivity 85-95%, specificity 94-99%) 6
- High-resolution CT (HRCT) is particularly useful for detecting subtle parenchymal abnormalities 1
Special Techniques
- Saline solution injection into the pleural cavity combined with vocalization during CT scanning can help detect the exact point of air leakage in persistent pneumothorax 5
- This technique does not require contrast medium or special instruments 5
Common Pitfalls in CT Interpretation
- Mistaking lung bullae for pneumothorax 6
- False positives can occur with lung contusions and adhesions 6
- Underestimating the importance of additional views in doubtful cases 6
CT scanning plays a crucial role in the evaluation of recurrent pneumothorax by identifying underlying lung abnormalities, guiding management decisions, and helping predict recurrence risk. The presence and extent of blebs and bullae on CT are particularly important findings that correlate with pneumothorax recurrence.