Q. A 31-year-old man has come to your clinic with fatigue, dyspnea, and peripheral edema. On physical examination, you find normal temperature, tachycardia (93/min), tachypnea (23/min), wide pulse pressure, systolic bruit over the carotid arteries, venous hum over the internal jugular vein, hyperdynamic precordium, grade II edema in both lower extremities below the knee. The patient’s BMI is 21.5 kg/m2. He is a professional soccer player and has no history of any disease. Forty-five days ago, following a car to pedestrian accident, he had an open left femoral fracture which was treated by wound management and internal fixation with an intramedullary nail. The thigh wound has healed well. Which diagnostic modality will help you identify the most probable etiology for the patient’s symptoms?