Diagnostic Approach to Chronic Cough
Key Recommendations
- The American College of Radiology guidelines recommend a non-contrast chest CT for evaluating chronic cough, as it is adequate for the majority of studies, with no direct comparison between contrast-enhanced and noncontrast-enhanced CT imaging in this context 1, 2, 3
- The American College of Radiology suggests that non-contrast chest CT is the reference standard for noninvasive diagnosis of bronchiectasis and interstitial lung disease, relevant pathologies in chronic cough workup 1, 3
Rationale for Non-Contrast CT
- Contrast-enhanced studies offer improved visualization of cardiopulmonary vasculature, mediastinal structures, and soft-tissue abnormalities, but these are not primary targets when evaluating chronic cough 1, 2
- The most common CT abnormalities associated with chronic cough are bronchiectasis and bronchial wall thickening, both of which are well-visualized without contrast 1, 4
Clinical Indications and Expected Findings
- Major pulmonary societies, including the American College of Chest Physicians, recommend chest CT only after common causes have been excluded or empirically treated, not as initial evaluation 5, 4
- Appropriate indications for chest CT include abnormal chest radiograph findings, failed empirical treatment for common causes, clinical suspicion of underlying structural pulmonary disease, and symptoms persisting beyond 8 weeks despite appropriate therapy 5, 4
- Expected findings on non-contrast CT include bronchial wall thickening, air trapping on expiratory images, bronchiectasis, centrilobular nodules, ground-glass opacities, and interstitial lung patterns 1, 3, 7
Red Flags and Clinical Algorithm
- Red flags warranting earlier CT consideration include hemoptysis, smoker >45 years with new or changed cough pattern, prominent dyspnea, systemic symptoms, and recurrent pneumonia 4
- The clinical algorithm involves starting with chest radiography, empirically treating common causes, and ordering non-contrast chest CT if initial treatment fails, chest X-ray shows abnormalities, red flag symptoms are present, or there is clinical suspicion of bronchiectasis or interstitial lung disease 4, 5, 8