Q. A 35-year-old woman presents to the emergency department with a sudden onset of shortness of breath and sharp chest pain that worsens upon inspiration. She recently had a long flight and has a history of oral contraceptive use. Her vital signs are: temperature 98.4°F (36.9°C), blood pressure 110/70 mmHg, heart rate 105 bpm, respiratory rate 24 breaths/min, and oxygen saturation 90% on room air. An ECG shows sinus tachycardia and S1Q3T3 pattern. Which of the following diagnostic tests would be most appropriate to confirm the suspected diagnosis?