Best CT Imaging Techniques for Multifocal Pneumonia Visualization
The optimal technique for visualizing multifocal pneumonia on CT is thin-section (1-1.25mm) multidetector CT with IV contrast, using a caudocranial scanning direction and proper timing of contrast administration (60 seconds post-injection). 1
Technical Parameters for Optimal Visualization
CT Acquisition Protocol
- Slice thickness: 1-1.25mm thin sections 2
- Provides superior detail assessment and reduces partial volume averaging
- Allows for near-isotropic data sets that enable high-quality multiplanar reformations
- Scanning direction: Caudocranial 2
- Reduces breathing artifacts if the patient cannot hold breath for the entire scan
- Contrast administration: 90-120mL with injection rate of 3-4mL/s 2, 1
- Proper timing (60 seconds post-injection) is essential for optimal pleural visualization
- Follow with saline flush to reduce artifacts in brachiocephalic veins
- Reconstruction interval: Overlapping reconstruction every 0.6-1mm 2
- Creates near-isotropic 3D dataset for multiplanar reformations
Key Imaging Findings in Multifocal Pneumonia
Typical Findings to Identify
- Ground-glass opacities (patchy or diffuse) 2, 3
- Consolidations (often multifocal and peribronchial) 3
- Centrilobular nodules (poorly defined, ground-glass attenuation) 2
- Mosaic attenuation pattern ("three-density sign") 2
- Air-trapping on expiratory images 2
- Peribronchovascular distribution 2
Complications to Assess
- Pleural effusions (look for pleural enhancement with IV contrast) 1
- Pleural thickening (seen in 98.7% of patients with pleural infection) 1
- Necrotizing pneumonia or abscess formation 2, 1
- Empyema (identified by pleural enhancement and thickening) 1
Clinical Applications and Pitfalls
When to Use CT for Pneumonia
- When chest radiographs are negative or equivocal but clinical suspicion remains high 2
- For evaluation of complications (abscess, empyema, bronchopleural fistula) 2, 1
- For assessment of nonresolving pneumonia 1
- For evaluation of the extent of disease in severe cases 2
Common Pitfalls to Avoid
- Inadequate contrast timing: Proper timing (60 seconds post-injection) is crucial for visualizing pleural complications 1
- Insufficient breath-hold instruction: Patient should cough immediately before exam to clear mucus that could be mistaken for lesions 2
- Improper slice thickness: Using standard 5-10mm slices instead of thin sections (1-1.25mm) will miss subtle findings 2
- Failing to obtain expiratory images: These are essential for detecting air-trapping, a key finding in certain types of pneumonia 2
- Misinterpreting patterns: Certain pneumonias (like eosinophilic) can mimic multifocal bacterial pneumonia 4
Special Considerations
- In immunocompromised patients, consider additional imaging protocols to detect opportunistic infections 3
- For suspected fungal pneumonia, look for specific signs like the "halo sign" or "air-crescent sign" 1
- In COVID-19 pneumonia, bilateral peripheral ground-glass opacities are characteristic findings 2
By following these technical parameters and focusing on the key imaging findings, radiologists and clinicians can optimize the detection and characterization of multifocal pneumonia on CT, leading to more accurate diagnosis and appropriate management.