Bronchiolitis Obliterans Organizing Pneumonia (BOOP) Radiology: A Comprehensive Review
Bronchiolitis Obliterans Organizing Pneumonia (BOOP) is a rare interstitial lung disease characterized by the infiltration of inflammatory cells and the formation of fibrosis in the small airways. Radiology plays a crucial role in the diagnosis, monitoring, and management of BOOP. This article provides a comprehensive review of the radiological features of BOOP, focusing on the imaging techniques, patterns, and differential diagnoses.
Imaging Techniques in BOOP
The primary imaging modalities used for diagnosing BOOP are chest radiography and high-resolution computed tomography (HRCT). Chest radiography is the initial imaging modality, often revealing a pattern of reticular nodular infiltrates, ground-glass opacities, or a combination of both. However, HRCT is considered the gold standard for diagnosing BOOP due to its superior spatial resolution and ability to detect subtle abnormalities in the lung parenchyma.
HRCT Patterns in BOOP
The characteristic HRCT patterns in BOOP include:
1. Bilateral, peripheral, and lower lung predominance: BOOP typically affects the lower lung fields, with a predilection for the peripheral areas.
2. Ground-glass opacities: These are often present and can be subtle, with a “cotton ball” appearance.
3. Reticular nodular infiltrates: These can be seen as fine or coarse reticulations, nodules, or a combination of both.
4. Airspace consolidation: This can occur in advanced cases, leading to a “consolidated lung” appearance.
5. Lobar or segmental collapse: This can be observed in severe cases, particularly in the lower lung fields.
Differential Diagnoses
The radiological patterns of BOOP can be similar to those of other interstitial lung diseases, making it essential to consider the differential diagnoses. These include:
1. Nonspecific interstitial pneumonia (NSIP): NSIP often presents with a similar pattern of ground-glass opacities and reticular nodular infiltrates.
2. Idiopathic pulmonary fibrosis (IPF): IPF can have a similar appearance, but it typically presents with a more aggressive clinical course and a more rapid progression.
3. Cryptogenic organizing pneumonia (COP): COP can mimic BOOP, but it often has a more acute onset and a higher incidence of associated autoimmunity.
4. Drug-induced lung disease: BOOP can be associated with the use of certain medications, such as azathioprine or methotrexate.
Conclusion
Radiology plays a vital role in the diagnosis and management of BOOP. Understanding the characteristic HRCT patterns and considering the differential diagnoses is crucial for accurate diagnosis and appropriate treatment. As new imaging techniques and therapeutic strategies continue to emerge, radiologists and pulmonologists must work together to improve the diagnosis and management of this challenging interstitial lung disease.
