A 58-yeаr-оld wоmаn presents tо the emergency depаrtment with sudden onset shortness of breath and pleuritic chest pain. She has a history of deep vein thrombosis (DVT) and recently underwent knee replacement surgery. Her heart rate is 110 bpm, blood pressure is 125/80 mmHg, and oxygen saturation is 91% on room air. D-dimer is elevated. Which imaging study is the most appropriate initial test to confirm the diagnosis in this hemodynamically stable patient?