From the Guidelines
Pneumonitis can be visualized on medical imaging, particularly on CT scans, which are more reliable than chest radiographs in identifying pulmonary infiltrates and ground glass changes. According to the most recent study 1, ground-glass opacities or patchy nodular infiltrates, predominantly in the lower lobes, are common findings on chest imaging in patients with pneumonitis. The study also reports that radiologic abnormalities vary but are often reported to be focal and very different from the diffuse pneumonitis associated with targeted agents.
Key Imaging Findings
- Ground-glass opacities
- Patchy nodular infiltrates
- Consolidation
- Reticular patterns in the lungs
- Distribution pattern can vary depending on the cause of pneumonitis
Importance of Clinical Correlation
Imaging findings alone are not diagnostic as they can overlap with other lung conditions such as pneumonia, pulmonary edema, or interstitial lung disease. Therefore, clinical correlation with symptoms, exposure history, laboratory tests, and sometimes lung biopsy is necessary for a definitive diagnosis, as suggested by 1 and 1. Serial imaging may be useful to monitor disease progression or response to treatment in cases of pneumonitis.
Role of Biopsy
The role of transbronchial biopsy is currently debated but generally not required, according to 1. However, biopsy may have a role in assisting to rule out other etiologies like lymphangitic spread of tumor or infection or distinguishing chronic ICPi pneumonitis, which appears to have an organizing pneumonia–like appearance. Ultimately, the decision to proceed with biopsy should be taken after careful risk-benefit analysis.
From the Research
Pneumonitis Visualization on Medical Imaging
- Pneumonitis can be visualized on medical imaging, including computed tomography (CT) scans and chest X-rays 2, 3, 4, 5, 6.
- CT scans have been shown to be more accurate than chest X-rays in diagnosing pneumonitis, particularly in ruling out the diagnosis and identifying alternative diagnoses 2.
- Different types of pneumonitis, such as radiation-induced pneumonitis and immune checkpoint inhibitor-associated pneumonitis, can exhibit distinct radiologic morphologies on CT scans 3.
- Functional lung imaging, such as perfusion SPECT/CT and FDG PET/CT, can also be used to assess lung function and predict the risk of pneumonitis 4.
- A CT pattern-based approach can be used to describe the imaging manifestations of pneumonitis from novel cancer therapies, including molecular targeted therapy and immune-checkpoint inhibitors 5.
- Chest CT scans can detect community-acquired pneumonia (CAP) even when chest radiography findings are negative, particularly in cases with ground-glass opacity or bronchiolitis-predominant patterns 6.
Imaging Features of Pneumonitis
- Radiation-induced pneumonitis tends to have unilateral CT changes with sharp borders 3.
- Immune checkpoint inhibitor-associated pneumonitis tends to have bilateral CT changes involving multiple lobes 3.
- Ground-glass opacity and bronchiolitis-predominant patterns are more common in CAP patients with negative chest radiography findings 6.
- Consolidation patterns are less common in CAP patients with negative chest radiography findings 6.
Clinical Implications
- The use of CT scans and other imaging modalities can improve the diagnosis and management of pneumonitis, particularly in patients with suspected pneumonia or those undergoing cancer treatment 2, 3, 5.
- Identifying the underlying cause of pneumonitis is crucial for guiding treatment decisions and improving patient outcomes 3, 5.
- Further research is needed to validate the use of imaging modalities in predicting the risk of pneumonitis and guiding treatment decisions 4, 5.