From the Guidelines
Imaging for COPD should typically begin with a chest X-ray, but high-resolution computed tomography (HRCT) is the gold standard for detecting emphysema, airway wall thickening, and air trapping, and is particularly useful for distinguishing COPD from other lung diseases and evaluating for complications. The initial diagnostic evaluation of patients with suspected COPD often includes chest radiography to exclude other diseases and establish the presence of concomitant respiratory diseases 1. However, chest radiography is not performed during routine follow-up of a stable patient with COPD. Some key points to consider when using imaging for COPD include:
- Chest X-ray can show hyperinflation, flattened diaphragms, and increased lung lucency, though it may be normal in early disease
- HRCT can detect emphysema, airway wall thickening, and air trapping even before pulmonary function tests become abnormal
- Quantitative CT can measure emphysema severity and distribution, which helps in phenotyping COPD subtypes
- Imaging becomes essential when symptoms are disproportionate to pulmonary function tests, when complications are suspected, or when planning surgical interventions like lung volume reduction surgery
- Pulmonary function tests remain the primary diagnostic tool for COPD, with imaging serving as a complementary approach that provides structural information about the lungs
- Repeated CT scans are not recommended for routine COPD monitoring due to radiation exposure concerns, but may be indicated when clinical deterioration occurs unexpectedly or complications are suspected, as supported by the American College of Radiology 1.
From the Research
Imaging for COPD
- High-resolution computed tomography (HRCT) is a useful diagnostic modality for chronic obstructive pulmonary disease (COPD) 2, 3, 4.
- HRCT features, such as emphysema index, lung volume, and vascular attenuation, can be used to evaluate the severity of COPD and predict the risk of acute exacerbation 3.
- HRCT can also distinguish areas of potentially reversible disease from irreversible fibrosis and guide the optimal type and site of lung biopsy 4.
- The use of HRCT in combination with pulmonary function tests and serum biomarkers, such as procalcitonin and high-sensitivity C-reactive protein, can improve the diagnosis and treatment of COPD 3.
HRCT Features and COPD Severity
- HRCT features, such as tracheal index, thoracic cage ratio, and sterno-aortic distance, can be used to evaluate the severity of COPD 2.
- The emphysema index, which is a measure of the extent of emphysema, can be used to predict the risk of acute exacerbation 3.
- The ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) can be used to evaluate the severity of airways obstruction 3.
Clinical Applications of HRCT in COPD
- HRCT can be used to diagnose and monitor COPD, as well as to guide treatment decisions 2, 3, 4.
- HRCT can also be used to evaluate the response to treatment and predict the risk of acute exacerbation 3.
- The use of HRCT in combination with other diagnostic modalities, such as pulmonary function tests and serum biomarkers, can improve the diagnosis and treatment of COPD 3.