Which imaging modality is preferred in the evaluation of suspected pulmonary embolism?

• A. Cardiac catheterization
• B. Nuclear medicine ventilation studies
• C. Helical computed tomography
• D. Transthoracic echocardiogram

Answer: (C)

When evaluating suspected pulmonary embolism, you want a test that quickly confirms or excludes the clot with high accuracy and provides useful additional information. Helical CT angiography directly visualizes filling defects in the pulmonary arteries, so it can promptly confirm the presence of an embolus and also reveal other thoracic problems that might mimic or accompany PE. This combination of speed, accuracy, accessibility, and the ability to assess related pathology makes it the preferred first-line imaging study in most settings.

Other options exist for special situations. Invasive cardiac catheterization is not used routinely for diagnosing PE due to its invasiveness. Nuclear medicine ventilation-perfusion scans were more common in the past and can be inconclusive or less specific, especially with abnormal chest radiographs. Transthoracic echocardiography can show signs of right-heart strain when PE causes hemodynamic instability but does not reliably visualize the clot itself, so it isn’t a definitive test for PE.