Chest X-Ray is Insufficient for Diagnosing Bronchiectasis
A chest X-ray alone is not sufficient for diagnosing bronchiectasis; high-resolution CT (HRCT) scanning is the diagnostic procedure of choice and should be ordered when bronchiectasis is suspected. 1
Diagnostic Limitations of Chest Radiography
Chest radiography has poor sensitivity for detecting bronchiectasis, missing ectatic airways in up to 34% of patients. 1
Bronchiectasis may be "sometimes obvious" on routine chest radiographs, but the diagnosis is usually established using HRCT scanning, which has sensitivity and specificity exceeding 90%. 1
In patients referred for CT evaluation of chronic cough with reportedly normal chest radiographs, bronchiectasis and bronchial wall thickening were identified in 27% and 21% of cases, respectively. 1
Physical examination findings (rhonchi, crackles, clubbing) are nonspecific and may be completely normal even in confirmed bronchiectasis, and do not correlate with HRCT findings. 1, 2
HRCT as the Gold Standard
HRCT is the reference standard for confirming bronchiectasis diagnosis, with false positive and negative rates of only 1% and 2% respectively. 2
The key diagnostic feature on HRCT is the "signet ring sign" - enlarged internal bronchial diameter where bronchi appear larger than the accompanying artery. 1
Additional HRCT findings include: failure of larger airways to taper toward the lung periphery, air-fluid levels in dilated airways, identification of airways in the extreme lung periphery, bronchial wall thickening, mucoid impaction, and focal air-trapping. 1
HRCT compares favorably with bronchography (the former gold standard), but is non-invasive, less risky, and equally accurate. 1
Recommended Diagnostic Algorithm
The European Respiratory Society recommends performing a baseline chest X-ray followed by thin-section CT scan to confirm the diagnosis when bronchiectasis is clinically suspected. 2
Volumetric CT with high-resolution technique is preferred over conventional HRCT alone, as contiguous 16-MDCT with 1-mm collimation is superior to HRCT at 10-mm intervals in showing the presence and extent of bronchiectasis. 3
Imaging should be conducted during clinically stable disease (not during acute exacerbations) for optimal diagnostic accuracy and to establish a baseline for serial comparisons. 2
Dose reduction techniques, including adaptive mA and kV with iterative reconstruction, should be applied when available. 2
Clinical Indications Warranting Investigation
Chronic productive cough persisting longer than 8 weeks with mucopurulent or purulent sputum production should trigger diagnostic workup. 2
Recurrent chest infections in at-risk populations require evaluation. 2
Patients with rheumatoid arthritis presenting with chronic productive cough or recurrent chest infections should be investigated, as bronchiectasis may precede RA diagnosis in 58% of cases. 2
Critical Pitfall to Avoid
Do not rely on chest X-ray alone or physical examination to diagnose or exclude bronchiectasis - proceed directly to HRCT when clinical suspicion exists based on chronic productive cough or recurrent infections. 1, 2 The substantial miss rate of chest radiography (up to 34% of cases) means that patients with genuine bronchiectasis will have delayed diagnosis, potentially missing the opportunity for early intervention that can stabilize or improve lung function. 1