Diagnostic Imaging for Chronic Cough

Initial Evaluation

The American College of Radiology and American College of Chest Physicians recommend chest radiography as the initial imaging test for patients with chronic cough lasting more than 8 weeks, followed by CT chest for persistent symptoms or concerning features 1
Chest radiography is recommended to exclude treatable and serious underlying pulmonary pathology, such as bronchiectasis, interstitial lung disease, neoplasms, and infectious processes, with abnormal radiography being positively associated with underlying primary pulmonary pathology other than asthma, with an odds ratio of 7.7 1

CT chest is indicated for patients with persistent symptoms despite initial clinical evaluation and empiric treatment, abnormal findings on chest radiograph requiring further characterization, and presence of red flag symptoms or increased risk for lung cancer, as recommended by the American College of Radiology 1
The American College of Radiology recommends proceeding to CT chest if symptoms persist despite optimal treatment, red flag symptoms are present, patient has risk factors for lung cancer, or abnormal findings on chest radiography 1
In patients with suspected occupational exposures, CT may detect abnormalities not visible on chest radiography 1

Low-dose CT techniques may be considered to reduce radiation exposure while maintaining diagnostic accuracy for most pulmonary abnormalities, as recommended by the American College of Radiology and the American College of Chest Physicians 1
High-Resolution CT (HRCT) is the reference standard for detecting bronchial abnormalities, with sensitivity and specificity exceeding 90% for detecting direct signs of bronchial disease, and can detect common findings in bronchitis, including bronchial wall thickening, mosaic attenuation on expiratory imaging, and peribronchial inflammation 1, 2, 3

HRCT can detect bronchiectasis and other bronchial abnormalities, characterized by abnormal dilation of airways with bronchial-arterial ratio >1, also known as the signet ring sign, as defined by the American College of Chest Physicians 4
Chest radiographs can show bronchial wall thickening, peribronchial cuffing, and hyperinflation, though they can be normal in up to 34% of patients with significant bronchial disease, according to the American College of Radiology and the American College of Chest Physicians 2, 1
The European Respiratory Society recommends evaluating for associated findings such as hyperinflation, flattening of diaphragm, or increased retrosternal airspace on chest x-ray 5

Patients with unintentional weight loss, fevers, chills, night sweats, productive cough, and CT findings of tree-in-bud nodularity with bronchial thickening should undergo immediate evaluation for pulmonary tuberculosis and other infectious etiologies, with sputum cultures, bronchoscopy with bronchoalveolar lavage, and appropriate microbiological testing, as recommended by the American College of Chest Physicians 2
Patients with risk factors for lung cancer, such as smoking history, hemoptysis, weight loss, and persistent symptoms despite empiric treatment, should be assessed for cancer suspicion, as recommended by the American College of Chest Physicians 6
Bronchoscopy is strongly indicated in smokers with persistent cough, especially with hemoptysis, as well as in patients with risk factors for lung cancer, even with normal chest radiograph findings, as stated by the American College of Chest Physicians 6

Non-infectious inflammatory conditions, including bronchiectasis and chronic bronchitis as part of COPD, can cause bronchial tree abnormalities, as reported by the American College of Radiology and the European Respiratory Society 1, 5, 3
Diffuse panbronchiolitis (DPB) is a non-infectious etiology that may be considered in the differential diagnosis, and low-dose macrolide therapy (e.g., erythromycin 200-600 mg/day for 2-6 months) has been shown to improve symptoms, biomarkers, and survival in DPB, with 5-year survival rates increasing from 50% to over 90%, as reported by the American College of Chest Physicians 2

Surgical lung biopsy should only be considered after HRCT has been performed to guide the biopsy location, as recommended by the American College of Radiology 1