From the Guidelines
For a patient in his 60s diagnosed with pneumonia (PNA) and pleural effusion on chest X-ray, a chest CT with IV contrast is the recommended initial imaging study. This recommendation is based on the most recent and highest quality study, which suggests that CT chest with IV contrast is the preferred imaging modality for patients with recent pneumonia and suspected parapneumonic effusion or empyema 1. The use of IV contrast enhances the visualization of the pleura and helps distinguish between empyema and simple parapneumonic effusion, which is crucial for guiding management decisions.
The American College of Radiology (ACR) appropriateness criteria also support the use of CT chest with IV contrast as the initial imaging study for patients with recent pneumonia and suspected parapneumonic effusion or empyema 1. The ACR recommends acquiring the CT scan 60 seconds after the IV contrast bolus to optimize visualization of the pleura.
Some key points to consider when interpreting the CT findings include:
- Pleural enhancement, which has the highest area under the curve for the diagnosis of empyema 1
- Pleural thickening, loculation, and extrapleural fat proliferation, which are also associated with empyema 1
- The size of the pleural effusion, with effusions <2.5 cm in anteroposterior dimension often being managed without thoracentesis 1
Overall, the use of chest CT with IV contrast as the initial imaging study provides valuable information for guiding management decisions, including whether drainage of the effusion is necessary, and helps to improve patient outcomes.
From the Research
Imaging Studies for Pneumonia and Pleural Effusion
- For a patient diagnosed with pneumonia and pleural effusion, imaging studies play a crucial role in further evaluation and management.
- According to the study by 2, chest radiographs (CXR) are not sufficient to identify parapneumonic effusions, and additional imaging such as computed tomography (CT) scan may be necessary.
- The study by 3 recommends thoracocentesis for parapneumonic effusions, and the results of the pleural fluid investigation can help categorize patients into different risk groups.
- Point-of-care ultrasound, in addition to chest radiography, is recommended by 4 to evaluate the pleural space and guide thoracentesis.
Recommended Imaging Studies
- Chest radiography (CXR) to determine laterality and detect moderate to large pleural effusions
- Point-of-care ultrasound to detect small effusions and features that could indicate complicated effusion or malignancy
- Computed tomography (CT) of the chest to exclude other causes of dyspnea and suggest complicated parapneumonic or malignant effusion
- Thoracocentesis to sample pleural fluid and guide further management, as recommended by 3 and 4
Considerations for Patient Management
- The patient's history and physical examination should guide evaluation, as recommended by 4
- Small bilateral effusions in patients with decompensated heart failure, cirrhosis, or kidney failure are likely transudative and do not require diagnostic thoracentesis, as stated by 4
- Pleural effusion in the setting of pneumonia may require additional testing, including thoracocentesis and pleural fluid analysis, as recommended by 3 and 4