What is the most appropriate initial test to order for a patient with worsening dyspnea (shortness of breath) on exertion and a history of hypertension, hyperlipidemia, and osteoarthritis?

High-Resolution CT Scan

Order a high-resolution CT scan of the chest now for this 65-year-old man with progressive dyspnea, bibasilar crackles, and significant smoking history, as these findings strongly suggest interstitial lung disease (ILD) requiring definitive imaging for diagnosis and management. 1

Clinical Reasoning

This patient presents with a classic triad pointing toward ILD:

• Progressive exertional dyspnea over 3 months with activity-related nonproductive cough 1
• Bibasilar crackles on examination with hypoxemia (92% oxygen saturation) 1
• 50 pack-year smoking history, a major risk factor for smoking-related ILD 1

The ACR Appropriateness Criteria explicitly state that CT without IV contrast is usually appropriate for the initial imaging of patients with chronic dyspnea and suspected ILD, particularly when predisposing factors exist. 1 While chest radiography is typically the first imaging study for chronic dyspnea of unclear etiology, the guidelines acknowledge that a normal chest radiograph does not exclude clinically important ILD. 1

Why CT Over Other Options

High-Resolution CT is Superior for ILD Detection

• CT detects ILD patterns missed by plain radiography, providing essential diagnostic information about the specific type and distribution of interstitial disease. 2
• The ACR guidelines prioritize CT for suspected ILD because it characterizes disease extent, guides potential biopsy sites, and establishes baseline severity for monitoring progression. 1

Why Not Echocardiogram First?

While cardiac causes (heart failure, valvular disease) are common in dyspnea, this patient lacks typical cardiac findings:

• No jugular venous distension, peripheral edema, or cardiac gallops 1
• Bibasilar crackles with end-expiratory wheezes suggest parenchymal lung disease rather than cardiogenic pulmonary edema 1
• Echocardiography would be appropriate if cardiac dysfunction were suspected, but the clinical picture points away from primary cardiac etiology 1

Why Not Hypersensitivity Pneumonitis Panel?

• Hypersensitivity pneumonitis panels are targeted serologic tests ordered after imaging establishes an ILD pattern consistent with HP 1
• The contractor/handyman occupation could involve exposures, but imaging must first confirm ILD and suggest HP pattern before ordering specific antibody panels 1

Why Not Surgical Lung Biopsy?

• Surgical biopsy is never the initial diagnostic test for suspected ILD 1
• Biopsy is reserved for cases where high-resolution CT findings are indeterminate or when tissue diagnosis would change management 1
• The diagnostic algorithm proceeds: clinical assessment → CT imaging → multidisciplinary discussion → biopsy only if needed 1

Critical Clinical Pitfalls

Do not delay CT imaging by ordering chest radiography first in this patient. While the ACR algorithm typically starts with chest radiography for undifferentiated chronic dyspnea 1, this patient has clear clinical features suggesting ILD (crackles, hypoxemia, smoking history). The guidelines explicitly state CT is appropriate as initial imaging when ILD is suspected, especially with predisposing factors. 1

Recognize that smoking-related ILD can progress rapidly. This patient's recent smoking cessation (4 weeks ago) after 50 pack-years suggests he may have respiratory bronchiolitis-ILD, desquamative interstitial pneumonia, or combined pulmonary fibrosis and emphysema—all requiring prompt CT characterization for prognosis and management decisions. 1

Order CT without IV contrast. The ACR specifies that for dyspnea evaluation, thin-section imaging of lung parenchyma is essential, and IV contrast is unnecessary unless vascular abnormalities are suspected. 1