From the Guidelines
COPD typically manifests on chest X-rays (CXR) with hyperinflation, hyperlucent lung fields, and diminished peripheral vascular markings, although early disease may show minimal or no changes. The characteristic findings on CXR include flattened diaphragms, increased retrosternal airspace, and a barrel-shaped chest with widened intercostal spaces 1. Lung fields often appear hyperlucent due to air trapping and destruction of lung tissue, with bullae visible as areas of decreased vascular markings, particularly in the upper lobes 1. The heart silhouette typically appears narrow and elongated, sometimes described as a "teardrop" heart, and pulmonary vascular markings are often diminished in the periphery but may appear more prominent centrally. Some key points to consider when interpreting CXR in COPD patients include:
- Hyperinflation is a key feature, but may not be evident in early disease
- Bullae and irregular radiolucency of the lung fields may be obvious in severe cases of emphysema
- The presence of such abnormalities is considered specific for emphysema in a patient with COPD 1
- CXR can exclude other conditions, such as lung cancer, and suggest cor pulmonale and pulmonary hypertension
- CT scans, particularly high-resolution CT, are more sensitive for detecting early emphysematous changes and for quantifying the extent of disease 1. It's essential to note that pulmonary function tests remain the gold standard for diagnosing and assessing COPD severity, even when radiographic findings are subtle 1.
From the Research
COPD Changes on CXR
- A plain chest X-ray is not useful for the diagnosis of early stage of COPD, but severe COPD has some characteristic radiographic signs 2
- Characteristic radiographic signs of severe COPD include:
- Absence of vasculature
- Radiolucency of lung fields
- Depression and flattening of the diaphragm
- Tear-drop heart
- Increase in the retrosternal airspace, which are signs of lung hyperinflation 2
- High-resolution CT (HRCT) scanning is more sensitive for diagnosing COPD and can detect low attenuation areas 2
- CT is also useful in classifying patterns of emphysema, including centriacinar, panacinar, and distal acinar type 2
Limitations of CXR in COPD Diagnosis
- CXR has limited utility in diagnosing early-stage COPD 2
- MRI assessment of COPD is still limited, but progress in MRI techniques such as hyperpolarized noble gas MRI and oxygen-enhanced MRI has enabled evaluation of COPD 2