A 54-year-old male presents with sudden pleuritic right-sided chest pain, acute dyspnea, and hemoptysis. Heart rate is 118 bpm, respiratory rate is 26/min, and oxygen saturation is 91% on room air. Wells score indicates high probability for pulmonary embolism. What is the definitive diagnostic imaging modality of choice in the absence of renal impairment?

Answer and explanation

Correct answer: A. Computed Tomography Pulmonary Angiography (CTPA)

  1. Step 1: CT Pulmonary Angiography (CTPA) is the international gold standard first-line diagnostic investigation for suspected pulmonary embolism in hemodynamically stable patients.
  2. Step 2: It provides high diagnostic sensitivity (> 90%) and specificity, directly visualizing intravascular filling defects within pulmonary arterial branches while ruling out alternative thoracic pathologies.
  3. Step 3: V/Q scanning is reserved for patients with severe renal failure or anaphylactic iodinated contrast allergy.
Answer
Computed Tomography Pulmonary Angiography (CTPA).
Why not the others: 'Transthoracic Echocardiogram' evaluates right ventricular strain but cannot definitively rule out PE; 'V/Q scan' is second-line when contrast is contraindicated; 'Upright chest radiograph' is usually normal or shows non-specific signs (Hampton's hump, Westermark sign).

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