Should I order a plain or contrast-enhanced chest Computed Tomography (CT) scan for a patient with a chronic cough?

Chest CT for Chronic Cough: Plain vs. Contrast

Order a non-contrast (plain) chest CT for your patient with chronic cough. 1

Key Recommendation

The American College of Radiology guidelines explicitly state that for chronic cough evaluation, the noncontrast technique appears to be adequate for the majority of studies, as no studies have directly compared contrast-enhanced versus noncontrast-enhanced CT imaging in this clinical context. 1

Rationale for Non-Contrast CT

• Contrast-enhanced studies offer improved visualization of cardiopulmonary vasculature, mediastinal structures, and soft-tissue abnormalities, but these are not the primary targets when evaluating chronic cough 1

• The most common CT abnormalities associated with chronic cough are bronchiectasis (28% of cases with normal chest X-rays) and bronchial wall thickening (21%), both of which are well-visualized without contrast 1, 2

• Non-contrast chest CT is considered the reference standard for noninvasive diagnosis of bronchiectasis and interstitial lung disease, the two most relevant pathologies in chronic cough workup 1

When CT Should Be Ordered

Major pulmonary societies recommend chest CT only after common causes have been excluded or empirically treated, not as initial evaluation. 1, 2

Appropriate indications include:

• Abnormal chest radiograph findings 1, 2
• Failed empirical treatment for common causes (post-nasal drip, asthma, GERD) 1, 2
• Clinical suspicion of underlying structural pulmonary disease 1
• Symptoms persisting beyond 8 weeks despite appropriate therapy 3, 4

Red flags warranting earlier CT consideration:

• Hemoptysis 2
• Smoker >45 years with new or changed cough pattern 2
• Prominent dyspnea 2
• Systemic symptoms 2
• Recurrent pneumonia 2

Important Caveats

• Wide application of chest CT in all patients with chronic cough has low clinical yield - studies show that 74 out of 81 patients were successfully managed clinically without CT 1

• In one study, 17 patients who underwent CT without specific clinical suspicion had no findings relevant to their management 1

• Up to 34% of chest radiographs appear normal despite CT-proven bronchiectasis, highlighting the limitation of plain films but also emphasizing selective CT use 1, 2

Clinical Algorithm

1. Start with chest radiography as recommended by ACCP and other pulmonary societies 2

2. Empirically treat common causes (upper airway cough syndrome, asthma, GERD) for 4-8 weeks 2, 3

3. Order non-contrast chest CT if:

   • Initial treatment fails 1, 2
   • Chest X-ray shows abnormalities 1
   • Red flag symptoms present 2
   • Clinical suspicion of bronchiectasis or interstitial lung disease 1, 2

4. Reserve contrast-enhanced CT for situations where vascular pathology or mediastinal masses are specifically suspected based on clinical presentation or initial imaging findings 1

Expected Findings on Non-Contrast CT

• Bronchial wall thickening (57-62% of chronic cough cases) 4
• Air trapping on expiratory images (31-35% of cases) 4
• Bronchiectasis 1, 2
• Centrilobular nodules 1
• Ground-glass opacities 1
• Interstitial lung patterns 1